13.0.0-96

UndoManager configuration to filter deletes
13.0.0-95
2019-08-20 22:29:56 +02:00 · 2019-08-20 22:28:49 +02:00 · 2019-08-09 01:18:15 +02:00 · 2019-08-09 01:16:40 +02:00 · 2019-08-09 01:15:46 +02:00 · 2019-06-29 14:47:34 +02:00
70 changed files with 5938 additions and 8320 deletions
--- a/.markdownlint.json
+++ b/.markdownlint.json
@@ -0,0 +1,4 @@
+{
+  "default": true,
+  "no-inline-html": false
+}
--- a/README.md
+++ b/README.md
@@ -6,8 +6,11 @@ text, richtext, json, or XML. It is fairly easy to get started, as Yjs hides
 most of the complexity of concurrent editing. For additional information, demos,
 and tutorials visit [y-js.org](http://y-js.org/).

+:warning: Checkout the [v13 docs](./README.v13.md) for the upcoming release :warning:
+
 ### Extensions
 Yjs only knows how to resolve conflicts on shared data. You have to choose a ..
+
 * *Connector* - a communication protocol that propagates changes to the clients
 * *Database* - a database to store your changes
 * one or more *Types* - that represent the shared data
@@ -33,7 +36,6 @@ is a list of the modules we know of:
 |[indexeddb](https://github.com/y-js/y-indexeddb) | Offline storage for the browser |
 |[leveldb](https://github.com/y-js/y-leveldb) | Persistent storage for node apps |

-
 ##### Types

 | Name     | Description       |
@@ -55,6 +57,7 @@ Install Yjs, and its modules with [bower](http://bower.io/), or
 [npm](https://www.npmjs.org/package/yjs).

 ### Bower
+
 ```
 bower install --save yjs y-array % add all y-* modules you want to use
 ```
@@ -65,6 +68,7 @@ missing modules.
 ```

 ### CDN
+
 ```
 <script src="https://cdn.jsdelivr.net/npm/yjs@12/dist/y.js"></script>
 <script src="https://cdn.jsdelivr.net/npm/y-array@10/dist/y-array.js"></script>
@@ -77,6 +81,7 @@ missing modules.
 ```

 ### Npm
+
 ```
 npm install --save yjs % add all y-* modules you want to use
 ```
@@ -95,6 +100,7 @@ require('y-text')(Y)
 ```

 ### ES6 Syntax
+
 ```
 import Y from 'yjs'
 import yArray from 'y-array'
@@ -107,6 +113,7 @@ Y.extend(yArray, yWebsocketsClient, yMemory, yArray, yMap, yText /*, .. */)
 ```

 # Text editing example
+
 Install dependencies
 ```
 bower i yjs y-memory y-webrtc y-array y-text
@@ -294,12 +301,5 @@ DEBUG_COLORS=0 DEBUG=y* node app.js > log
 localStorage.debug = 'y*'
 ```

-## Contribution
-I created this framework during my bachelor thesis at the chair of computer
-science 5 [(i5)](http://dbis.rwth-aachen.de/cms), RWTH University. Since
-December 2014 I'm working on Yjs as a part of my student worker job at the i5.
-
 ## License
 Yjs is licensed under the [MIT License](./LICENSE).
-
-<yjs@dbis.rwth-aachen.de>
--- a/README.v13.md
+++ b/README.v13.md
--- a/examples/.gitignore
+++ b/examples/.gitignore
@@ -1 +0,0 @@
-build
--- a/examples/codemirror.html
+++ b/examples/codemirror.html
@@ -1,70 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-    <title>Yjs CodeMirror Example</title>
-    <link rel=stylesheet href="https://codemirror.net/lib/codemirror.css">
-    <style>
-      #container {
-        border: grey;
-        border-style: solid;
-        border-width: thin;
-      }
-    </style>
-  </head>
-<body>
-  <p>This example shows how to bind a YText type to <a href="https://codemirror.net/">CodeMirror</a> editor.</p>
-  <p>The content of this editor is shared with every client who visits this domain.</p>
-  <div class="code-html">
-<style>
-.remote-caret {
-  position: absolute;
-  border-left: black;
-  border-left-style: solid;
-  border-left-width: 2px;
-  height: 1em;
-}
-.remote-caret > div {
-  position: relative;
-  top: -1.05em;
-  font-size: 13px;
-  background-color: rgb(250, 129, 0);
-  font-family: serif;
-  font-style: normal;
-  font-weight: normal;
-  line-height: normal;
-  user-select: none;
-  color: white;
-  padding-left: 2px;
-  padding-right: 2px;
-}
-</style>
-<div id="container"></div>
-  </div>
-  <!-- The actual source file for the following code is found in ./codemirror.js. Run `npm run watch` to compile the files -->
-  <script class="code-js" src="./build/codemirror.js" type="module">
-import * as Y from 'yjs'
-import { WebsocketProvider } from 'yjs/provider/websocket.js'
-import { CodeMirrorBinding } from 'yjs/bindings/codemirror.js'
-
-import * as conf from './exampleConfig.js'
-
-import CodeMirror from 'codemirror'
-import 'codemirror/mode/javascript/javascript.js'
-
-const provider = new WebsocketProvider(conf.serverAddress)
-const ydocument = provider.get('codemirror')
-const ytext = ydocument.define('codemirror', Y.Text)
-
-const editor = new CodeMirror(document.querySelector('#container'), {
-    mode: 'javascript',
-    lineNumbers: true
-})
-
-const binding = new CodeMirrorBinding(ytext, editor)
-
-window.codemirrorExample = {
-  binding, editor, ytext, ydocument
-}
-  </script>
-</body>
-</html>
--- a/examples/codemirror.js
+++ b/examples/codemirror.js
@@ -1,22 +0,0 @@
-import { WebsocketProvider } from 'y-websocket'
-import { CodeMirrorBinding } from 'y-codemirror'
-
-import * as conf from './exampleConfig.js'
-
-import CodeMirror from 'codemirror'
-import 'codemirror/mode/javascript/javascript.js'
-
-const provider = new WebsocketProvider(conf.serverAddress)
-const ydocument = provider.get('codemirror')
-const ytext = ydocument.getText('codemirror')
-
-const editor = new CodeMirror(document.querySelector('#container'), {
-  mode: 'javascript',
-  lineNumbers: true
-})
-
-const binding = new CodeMirrorBinding(ytext, editor)
-
-window.codemirrorExample = {
-  binding, editor, ytext, ydocument
-}
--- a/examples/dom.html
+++ b/examples/dom.html
@@ -1,37 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-    <title>Yjs Prosemirror Example</title>
-    <link rel=stylesheet href="https://prosemirror.net/css/editor.css">
-    <style>
-      #content {
-        min-height: 500px;
-      }
-    </style>
-</head>
-<body>
-  <p>This example shows how to bind a YXmlFragment type to an arbitrary DOM element. We set the DOM element to contenteditable so it basically behaves like a very powerful rich-text editor.</p>
-  <p>The content of this editor is shared with every client who visits this domain.</p>
-  <hr>
-  <div class="code-html">
-
-<div id="content" contenteditable=""></div>
-  </div>
-  <!-- The actual source file for the following code is found in ./dom.js. Run `npm run watch` to compile the files -->
-  <script class="code-js" src="./build/dom.js" type="module">
-    import * as Y from 'yjs/index.js'
-    import { WebsocketProvider } from 'yjs/provider/websocket.js'
-    import { DomBinding } from 'yjs/bindings/dom.js'
-    import * as conf from './exampleConfig.js'
-
-    const provider = new WebsocketProvider(conf.serverAddress)
-    const ydocument = provider.get('dom')
-    const type = ydocument.define('xml', Y.XmlFragment)
-    const binding = new DomBinding(type, document.querySelector('#content'), { scrollingElement: document.scrollingElement })
-
-    window.example = {
-      provider, ydocument, type, binding
-    }
-  </script>
-</body>
-</html>
--- a/examples/dom.js
+++ b/examples/dom.js
@@ -1,13 +0,0 @@
-import * as Y from '../src/index.js'
-import { WebsocketProvider } from 'y-websocket'
-import { DomBinding } from 'y-dom'
-import * as conf from './exampleConfig.js'
-
-const provider = new WebsocketProvider(conf.serverAddress)
-const ydocument = provider.get('dom')
-const type = ydocument.define('xml', Y.XmlFragment)
-const binding = new DomBinding(type, document.querySelector('#content'), { scrollingElement: document.scrollingElement })
-
-window.example = {
-  provider, ydocument, type, binding
-}
--- a/examples/exampleConfig.js
+++ b/examples/exampleConfig.js
@@ -1,9 +0,0 @@
-/* eslint-env browser */
-
-const isDeployed = location.hostname === 'yjs.website'
-
-if (!isDeployed) {
-  console.log('%cYjs: Start your local websocket server by running %c`npm run websocket-server`', 'color:blue', 'color: grey; font-weight: bold')
-}
-
-export const serverAddress = isDeployed ? 'wss://api.yjs.website' : 'ws://localhost:1234'
--- a/examples/examples.json
+++ b/examples/examples.json
@@ -1,17 +0,0 @@
-{
-  "codemirror": {
-    "title": "CodeMirror Binding"
-  },
-  "prosemirror": {
-    "title": "ProseMirror Binding"
-  },
-  "textarea": {
-    "title": "Textarea Binding"
-  },
-  "quill": {
-    "title": "Quill Binding"
-  },
-  "dom": {
-    "title": "Dom Binding"
-  }
-}
--- a/examples/prosemirror-history.js
+++ b/examples/prosemirror-history.js
@@ -1,159 +0,0 @@
-
-import { Plugin } from 'prosemirror-state'
-import crel from 'crel'
-import * as Y from '../src/index.js'
-import { prosemirrorPluginKey } from 'y-prosemirror'
-import * as encoding from 'lib0/encoding.js'
-import * as decoding from 'lib0/decoding.js'
-import * as historyProtocol from 'y-protocols/history.js'
-
-const niceColors = ['#3cb44b', '#4363d8', '#f58231', '#911eb4', '#46f0f0', '#f032e6', '#bcf60c', '#008080', '#9a6324', '#800000', '#808000', '#000075', '#808080']
-
-const createUserCSS = (userid, username, color = 'rgb(250, 129, 0)', color2 = 'rgba(250, 129, 0, .41)') => `
-  [ychange_state][ychange_user="${userid}"]:hover::before {
-    content: "${username}" !important;
-    background-color: ${color} !important;
-  }
-  [ychange_state="added"][ychange_user="${userid}"] {
-    background-color: ${color2} !important;
-  }
-  [ychange_state="removed"][ychange_user="${userid}"] {
-    color: ${color} !important;
-  }
-`
-
-export const noteHistoryPlugin = new Plugin({
-  state: {
-    init (initargs, state) {
-      return new NoteHistoryPlugin()
-    },
-    apply (tr, pluginState) {
-      return pluginState
-    }
-  },
-  view (editorView) {
-    const hstate = noteHistoryPlugin.getState(editorView.state)
-    hstate.init(editorView)
-    return {
-      destroy: hstate.destroy.bind(hstate)
-    }
-  }
-})
-
-const createWrapper = () => {
-  const wrapper = crel('div', { style: 'display: flex;' })
-  const historyContainer = crel('div', { style: 'align-self: baseline; flex-basis: 250px;', class: 'shared-history' })
-  wrapper.insertBefore(historyContainer, null)
-  const userStyleContainer = crel('style')
-  wrapper.insertBefore(userStyleContainer, null)
-  return { wrapper, historyContainer, userStyleContainer }
-}
-
-class NoteHistoryPlugin {
-  init (editorView) {
-    this.editorView = editorView
-    const { historyContainer, wrapper, userStyleContainer } = createWrapper()
-    this.userStyleContainer = userStyleContainer
-    this.wrapper = wrapper
-    this.historyContainer = historyContainer
-    const n = editorView.dom.parentNode.parentNode
-    n.parentNode.replaceChild(this.wrapper, n)
-    n.style['flex-grow'] = '1'
-    wrapper.insertBefore(n, this.wrapper.firstChild)
-    this.render()
-    const y = prosemirrorPluginKey.getState(this.editorView.state).y
-    const history = y.define('history', Y.Array)
-    history.observe(this.render.bind(this))
-  }
-  destroy () {
-    this.wrapper.parentNode.replaceChild(this.wrapper.firstChild, this.wrapper)
-    const y = prosemirrorPluginKey.getState(this.editorView.state).y
-    const history = y.define('history', Y.Array)
-    history.unobserve(this.render)
-  }
-  render () {
-    const y = prosemirrorPluginKey.getState(this.editorView.state).y
-    const history = y.define('history', Y.Array).toArray()
-    const fragment = document.createDocumentFragment()
-    const snapshotBtn = crel('button', { type: 'button' }, ['snapshot'])
-    fragment.insertBefore(snapshotBtn, null)
-    let _prevSnap = null // empty
-    snapshotBtn.addEventListener('click', () => {
-      const awareness = y.getAwarenessInfo()
-      const userMap = new Map()
-      const aw = y.getLocalAwarenessInfo()
-      userMap.set(y.userID, aw.name || 'unknown')
-      awareness.forEach((a, userID) => {
-        userMap.set(userID, a.name || 'Unknown')
-      })
-      this.snapshot(userMap)
-    })
-    history.forEach(buf => {
-      const decoder = decoding.createDecoder(buf)
-      const snapshot = historyProtocol.readHistorySnapshot(decoder)
-      const date = new Date(decoding.readUint32(decoder) * 1000)
-      const restoreBtn = crel('button', { type: 'button' }, ['restore'])
-      const a = crel('a', [
-        '• ' + date.toUTCString(), restoreBtn
-      ])
-      const el = crel('div', [ a ])
-      let prevSnapshot = _prevSnap // rebind to new variable
-      restoreBtn.addEventListener('click', event => {
-        if (prevSnapshot === null) {
-          prevSnapshot = { ds: snapshot.ds, sm: new Map() }
-        }
-        this.editorView.dispatch(this.editorView.state.tr.setMeta(prosemirrorPluginKey, { snapshot, prevSnapshot, restore: true }))
-        event.stopPropagation()
-      })
-      a.addEventListener('click', () => {
-        console.log('setting snapshot')
-        if (prevSnapshot === null) {
-          prevSnapshot = { ds: snapshot.ds, sm: new Map() }
-        }
-        this.renderSnapshot(snapshot, prevSnapshot)
-      })
-      fragment.insertBefore(el, null)
-      _prevSnap = snapshot
-    })
-    this.historyContainer.innerHTML = ''
-    this.historyContainer.insertBefore(fragment, null)
-  }
-  renderSnapshot (snapshot, prevSnapshot) {
-    this.editorView.dispatch(this.editorView.state.tr.setMeta(prosemirrorPluginKey, { snapshot, prevSnapshot }))
-    /**
-     * @type {Array<string|null>}
-     */
-    let colors = niceColors.slice()
-    let style = ''
-    snapshot.userMap.forEach((name, userid) => {
-      /**
-       * @type {any}
-       */
-      const randInt = name.split('').map(s => s.charCodeAt(0)).reduce((a, b) => a + b)
-      let color = null
-      let i = 0
-      for (; i < colors.length && color === null; i++) {
-        color = colors[(randInt + i) % colors.length]
-      }
-      if (color === null) {
-        colors = niceColors.slice()
-        i = 0
-        color = colors[randInt % colors.length]
-      }
-      colors[randInt % colors.length] = null
-      style += createUserCSS(userid, name, color, color + '69')
-    })
-    this.userStyleContainer.innerHTML = style
-  }
-  /**
-   * @param {Map<number, string>} [updatedUserMap] Maps from userid (yjs model) to account name (e.g. mail address)
-   */
-  snapshot (updatedUserMap = new Map()) {
-    const y = prosemirrorPluginKey.getState(this.editorView.state).y
-    const history = y.define('history', Y.Array)
-    const encoder = encoding.createEncoder()
-    historyProtocol.writeHistorySnapshot(encoder, y, updatedUserMap)
-    encoding.writeUint32(encoder, Math.floor(Date.now() / 1000))
-    history.push([encoding.toBuffer(encoder)])
-  }
-}
--- a/examples/prosemirror-schema.js
+++ b/examples/prosemirror-schema.js
@@ -1,197 +0,0 @@
-import { Schema } from 'prosemirror-model'
-
-const brDOM = ['br']
-
-const calcYchangeDomAttrs = (attrs, domAttrs = {}) => {
-  domAttrs = Object.assign({}, domAttrs)
-  if (attrs.ychange !== null) {
-    domAttrs.ychange_user = attrs.ychange.user
-    domAttrs.ychange_state = attrs.ychange.state
-  }
-  return domAttrs
-}
-
-// :: Object
-// [Specs](#model.NodeSpec) for the nodes defined in this schema.
-export const nodes = {
-  // :: NodeSpec The top level document node.
-  doc: {
-    content: 'block+'
-  },
-
-  // :: NodeSpec A plain paragraph textblock. Represented in the DOM
-  // as a `<p>` element.
-  paragraph: {
-    attrs: { ychange: { default: null } },
-    content: 'inline*',
-    group: 'block',
-    parseDOM: [{ tag: 'p' }],
-    toDOM (node) { return ['p', calcYchangeDomAttrs(node.attrs), 0] }
-  },
-
-  // :: NodeSpec A blockquote (`<blockquote>`) wrapping one or more blocks.
-  blockquote: {
-    attrs: { ychange: { default: null } },
-    content: 'block+',
-    group: 'block',
-    defining: true,
-    parseDOM: [{ tag: 'blockquote' }],
-    toDOM (node) { return ['blockquote', calcYchangeDomAttrs(node.attrs), 0] }
-  },
-
-  // :: NodeSpec A horizontal rule (`<hr>`).
-  horizontal_rule: {
-    attrs: { ychange: { default: null } },
-    group: 'block',
-    parseDOM: [{ tag: 'hr' }],
-    toDOM (node) {
-      return ['hr', calcYchangeDomAttrs(node.attrs)]
-    }
-  },
-
-  // :: NodeSpec A heading textblock, with a `level` attribute that
-  // should hold the number 1 to 6. Parsed and serialized as `<h1>` to
-  // `<h6>` elements.
-  heading: {
-    attrs: {
-      level: { default: 1 },
-      ychange: { default: null }
-    },
-    content: 'inline*',
-    group: 'block',
-    defining: true,
-    parseDOM: [{ tag: 'h1', attrs: { level: 1 } },
-      { tag: 'h2', attrs: { level: 2 } },
-      { tag: 'h3', attrs: { level: 3 } },
-      { tag: 'h4', attrs: { level: 4 } },
-      { tag: 'h5', attrs: { level: 5 } },
-      { tag: 'h6', attrs: { level: 6 } }],
-    toDOM (node) { return ['h' + node.attrs.level, calcYchangeDomAttrs(node.attrs), 0] }
-  },
-
-  // :: NodeSpec A code listing. Disallows marks or non-text inline
-  // nodes by default. Represented as a `<pre>` element with a
-  // `<code>` element inside of it.
-  code_block: {
-    attrs: { ychange: { default: null } },
-    content: 'text*',
-    marks: '',
-    group: 'block',
-    code: true,
-    defining: true,
-    parseDOM: [{ tag: 'pre', preserveWhitespace: 'full' }],
-    toDOM (node) { return ['pre', calcYchangeDomAttrs(node.attrs), ['code', 0]] }
-  },
-
-  // :: NodeSpec The text node.
-  text: {
-    group: 'inline'
-  },
-
-  // :: NodeSpec An inline image (`<img>`) node. Supports `src`,
-  // `alt`, and `href` attributes. The latter two default to the empty
-  // string.
-  image: {
-    inline: true,
-    attrs: {
-      ychange: { default: null },
-      src: {},
-      alt: { default: null },
-      title: { default: null }
-    },
-    group: 'inline',
-    draggable: true,
-    parseDOM: [{ tag: 'img[src]',
-      getAttrs (dom) {
-        return {
-          src: dom.getAttribute('src'),
-          title: dom.getAttribute('title'),
-          alt: dom.getAttribute('alt')
-        }
-      } }],
-    toDOM (node) {
-      const domAttrs = {
-        src: node.attrs.src,
-        title: node.attrs.title,
-        alt: node.attrs.alt
-      }
-      return ['img', calcYchangeDomAttrs(node.attrs, domAttrs)]
-    }
-  },
-
-  // :: NodeSpec A hard line break, represented in the DOM as `<br>`.
-  hard_break: {
-    inline: true,
-    group: 'inline',
-    selectable: false,
-    parseDOM: [{ tag: 'br' }],
-    toDOM () { return brDOM }
-  }
-}
-
-const emDOM = ['em', 0]; const strongDOM = ['strong', 0]; const codeDOM = ['code', 0]
-
-// :: Object [Specs](#model.MarkSpec) for the marks in the schema.
-export const marks = {
-  // :: MarkSpec A link. Has `href` and `title` attributes. `title`
-  // defaults to the empty string. Rendered and parsed as an `<a>`
-  // element.
-  link: {
-    attrs: {
-      href: {},
-      title: { default: null }
-    },
-    inclusive: false,
-    parseDOM: [{ tag: 'a[href]',
-      getAttrs (dom) {
-        return { href: dom.getAttribute('href'), title: dom.getAttribute('title') }
-      } }],
-    toDOM (node) { return ['a', node.attrs, 0] }
-  },
-
-  // :: MarkSpec An emphasis mark. Rendered as an `<em>` element.
-  // Has parse rules that also match `<i>` and `font-style: italic`.
-  em: {
-    parseDOM: [{ tag: 'i' }, { tag: 'em' }, { style: 'font-style=italic' }],
-    toDOM () { return emDOM }
-  },
-
-  // :: MarkSpec A strong mark. Rendered as `<strong>`, parse rules
-  // also match `<b>` and `font-weight: bold`.
-  strong: {
-    parseDOM: [{ tag: 'strong' },
-      // This works around a Google Docs misbehavior where
-      // pasted content will be inexplicably wrapped in `<b>`
-      // tags with a font-weight normal.
-      { tag: 'b', getAttrs: node => node.style.fontWeight !== 'normal' && null },
-      { style: 'font-weight', getAttrs: value => /^(bold(er)?|[5-9]\d{2,})$/.test(value) && null }],
-    toDOM () { return strongDOM }
-  },
-
-  // :: MarkSpec Code font mark. Represented as a `<code>` element.
-  code: {
-    parseDOM: [{ tag: 'code' }],
-    toDOM () { return codeDOM }
-  },
-  ychange: {
-    attrs: {
-      user: { default: null },
-      state: { default: null }
-    },
-    inclusive: false,
-    parseDOM: [{ tag: 'ychange' }],
-    toDOM (node) {
-      return ['ychange', { ychange_user: node.attrs.user, ychange_state: node.attrs.state }, 0]
-    }
-  }
-}
-
-// :: Schema
-// This schema rougly corresponds to the document schema used by
-// [CommonMark](http://commonmark.org/), minus the list elements,
-// which are defined in the [`prosemirror-schema-list`](#schema-list)
-// module.
-//
-// To reuse elements from this schema, extend or read from its
-// `spec.nodes` and `spec.marks` [properties](#model.Schema.spec).
-export const schema = new Schema({ nodes, marks })
--- a/examples/prosemirror.css
+++ b/examples/prosemirror.css
@@ -1,330 +0,0 @@
-.ProseMirror {
-  position: relative;
-}
-
-.ProseMirror {
-  word-wrap: break-word;
-  white-space: pre-wrap;
-  -webkit-font-variant-ligatures: none;
-  font-variant-ligatures: none;
-}
-
-.ProseMirror pre {
-  white-space: pre-wrap;
-}
-
-.ProseMirror li {
-  position: relative;
-}
-
-.ProseMirror-hideselection *::selection { background: transparent; }
-.ProseMirror-hideselection *::-moz-selection { background: transparent; }
-.ProseMirror-hideselection { caret-color: transparent; }
-
-.ProseMirror-selectednode {
-  outline: 2px solid #8cf;
-}
-
-/* Make sure li selections wrap around markers */
-
-li.ProseMirror-selectednode {
-  outline: none;
-}
-
-li.ProseMirror-selectednode:after {
-  content: "";
-  position: absolute;
-  left: -32px;
-  right: -2px; top: -2px; bottom: -2px;
-  border: 2px solid #8cf;
-  pointer-events: none;
-}
-.ProseMirror-textblock-dropdown {
-  min-width: 3em;
-}
-
-.ProseMirror-menu {
-  margin: 0 -4px;
-  line-height: 1;
-}
-
-.ProseMirror-tooltip .ProseMirror-menu {
-  width: -webkit-fit-content;
-  width: fit-content;
-  white-space: pre;
-}
-
-.ProseMirror-menuitem {
-  margin-right: 3px;
-  display: inline-block;
-}
-
-.ProseMirror-menuseparator {
-  border-right: 1px solid #ddd;
-  margin-right: 3px;
-}
-
-.ProseMirror-menu-dropdown, .ProseMirror-menu-dropdown-menu {
-  font-size: 90%;
-  white-space: nowrap;
-}
-
-.ProseMirror-menu-dropdown {
-  vertical-align: 1px;
-  cursor: pointer;
-  position: relative;
-  padding-right: 15px;
-}
-
-.ProseMirror-menu-dropdown-wrap {
-  padding: 1px 0 1px 4px;
-  display: inline-block;
-  position: relative;
-}
-
-.ProseMirror-menu-dropdown:after {
-  content: "";
-  border-left: 4px solid transparent;
-  border-right: 4px solid transparent;
-  border-top: 4px solid currentColor;
-  opacity: .6;
-  position: absolute;
-  right: 4px;
-  top: calc(50% - 2px);
-}
-
-.ProseMirror-menu-dropdown-menu, .ProseMirror-menu-submenu {
-  position: absolute;
-  background: white;
-  color: #666;
-  border: 1px solid #aaa;
-  padding: 2px;
-}
-
-.ProseMirror-menu-dropdown-menu {
-  z-index: 15;
-  min-width: 6em;
-}
-
-.ProseMirror-menu-dropdown-item {
-  cursor: pointer;
-  padding: 2px 8px 2px 4px;
-}
-
-.ProseMirror-menu-dropdown-item:hover {
-  background: #f2f2f2;
-}
-
-.ProseMirror-menu-submenu-wrap {
-  position: relative;
-  margin-right: -4px;
-}
-
-.ProseMirror-menu-submenu-label:after {
-  content: "";
-  border-top: 4px solid transparent;
-  border-bottom: 4px solid transparent;
-  border-left: 4px solid currentColor;
-  opacity: .6;
-  position: absolute;
-  right: 4px;
-  top: calc(50% - 4px);
-}
-
-.ProseMirror-menu-submenu {
-  display: none;
-  min-width: 4em;
-  left: 100%;
-  top: -3px;
-}
-
-.ProseMirror-menu-active {
-  background: #eee;
-  border-radius: 4px;
-}
-
-.ProseMirror-menu-active {
-  background: #eee;
-  border-radius: 4px;
-}
-
-.ProseMirror-menu-disabled {
-  opacity: .3;
-}
-
-.ProseMirror-menu-submenu-wrap:hover .ProseMirror-menu-submenu, .ProseMirror-menu-submenu-wrap-active .ProseMirror-menu-submenu {
-  display: block;
-}
-
-.ProseMirror-menubar {
-  border-top-left-radius: inherit;
-  border-top-right-radius: inherit;
-  position: relative;
-  min-height: 1em;
-  color: #666;
-  padding: 1px 6px;
-  top: 0; left: 0; right: 0;
-  border-bottom: 1px solid silver;
-  background: white;
-  z-index: 10;
-  -moz-box-sizing: border-box;
-  box-sizing: border-box;
-  overflow: visible;
-}
-
-.ProseMirror-icon {
-  display: inline-block;
-  line-height: .8;
-  vertical-align: -2px; /* Compensate for padding */
-  padding: 2px 8px;
-  cursor: pointer;
-}
-
-.ProseMirror-menu-disabled.ProseMirror-icon {
-  cursor: default;
-}
-
-.ProseMirror-icon svg {
-  fill: currentColor;
-  height: 1em;
-}
-
-.ProseMirror-icon span {
-  vertical-align: text-top;
-}
-.ProseMirror-gapcursor {
-  display: none;
-  pointer-events: none;
-  position: absolute;
-}
-
-.ProseMirror-gapcursor:after {
-  content: "";
-  display: block;
-  position: absolute;
-  top: -2px;
-  width: 20px;
-  border-top: 1px solid black;
-  animation: ProseMirror-cursor-blink 1.1s steps(2, start) infinite;
-}
-
-@keyframes ProseMirror-cursor-blink {
-  to {
-    visibility: hidden;
-  }
-}
-
-.ProseMirror-focused .ProseMirror-gapcursor {
-  display: block;
-}
-/* Add space around the hr to make clicking it easier */
-
-.ProseMirror-example-setup-style hr {
-  padding: 2px 10px;
-  border: none;
-  margin: 1em 0;
-}
-
-.ProseMirror-example-setup-style hr:after {
-  content: "";
-  display: block;
-  height: 1px;
-  background-color: silver;
-  line-height: 2px;
-}
-
-.ProseMirror ul, .ProseMirror ol {
-  padding-left: 30px;
-}
-
-.ProseMirror blockquote {
-  padding-left: 1em;
-  border-left: 3px solid #eee;
-  margin-left: 0; margin-right: 0;
-}
-
-.ProseMirror-example-setup-style img {
-  cursor: default;
-}
-
-.ProseMirror-prompt {
-  background: white;
-  padding: 5px 10px 5px 15px;
-  border: 1px solid silver;
-  position: fixed;
-  border-radius: 3px;
-  z-index: 11;
-  box-shadow: -.5px 2px 5px rgba(0, 0, 0, .2);
-}
-
-.ProseMirror-prompt h5 {
-  margin: 0;
-  font-weight: normal;
-  font-size: 100%;
-  color: #444;
-}
-
-.ProseMirror-prompt input[type="text"],
-.ProseMirror-prompt textarea {
-  background: #eee;
-  border: none;
-  outline: none;
-}
-
-.ProseMirror-prompt input[type="text"] {
-  padding: 0 4px;
-}
-
-.ProseMirror-prompt-close {
-  position: absolute;
-  left: 2px; top: 1px;
-  color: #666;
-  border: none; background: transparent; padding: 0;
-}
-
-.ProseMirror-prompt-close:after {
-  content: "✕";
-  font-size: 12px;
-}
-
-.ProseMirror-invalid {
-  background: #ffc;
-  border: 1px solid #cc7;
-  border-radius: 4px;
-  padding: 5px 10px;
-  position: absolute;
-  min-width: 10em;
-}
-
-.ProseMirror-prompt-buttons {
-  margin-top: 5px;
-  display: none;
-}
-#editor, .editor {
-  background: white;
-  color: black;
-  background-clip: padding-box;
-  border-radius: 4px;
-  border: 2px solid rgba(0, 0, 0, 0.2);
-  padding: 5px 0;
-  margin-bottom: 23px;
-}
-
-.ProseMirror p:first-child,
-.ProseMirror h1:first-child,
-.ProseMirror h2:first-child,
-.ProseMirror h3:first-child,
-.ProseMirror h4:first-child,
-.ProseMirror h5:first-child,
-.ProseMirror h6:first-child {
-  margin-top: 10px;
-}
-
-.ProseMirror {
-  padding: 4px 8px 4px 14px;
-  line-height: 1.2;
-  outline: none;
-}
-
-.ProseMirror p { margin-bottom: 1em }
-
--- a/examples/prosemirror.html
+++ b/examples/prosemirror.html
@@ -1,117 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-    <title>Yjs Prosemirror Example</title>
-    <link rel=stylesheet href="./prosemirror.css">
-    <style>
-      placeholder {
-        display: inline;
-        border: 1px solid #ccc;
-        color: #ccc;
-      }
-      placeholder:after {
-        content: "☁";
-        font-size: 200%;
-        line-height: 0.1;
-        font-weight: bold;
-      }
-      .ProseMirror img { max-width: 100px }
-      /* this is a rough fix for the first cursor position when the first paragraph is empty */
-      .ProseMirror > .ProseMirror-yjs-cursor:first-child {
-        margin-top: 16px;
-      }
-      .ProseMirror p:first-child, .ProseMirror h1:first-child, .ProseMirror h2:first-child, .ProseMirror h3:first-child, .ProseMirror h4:first-child, .ProseMirror h5:first-child, .ProseMirror h6:first-child {
-        margin-top: 16px
-      }
-      .ProseMirror-yjs-cursor {
-        position: absolute;
-        border-left: black;
-        border-left-style: solid;
-        border-left-width: 2px;
-        border-color: orange;
-        height: 1em;
-        word-break: normal;
-      }
-      .ProseMirror-yjs-cursor > div {
-        position: relative;
-        top: -1.05em;
-        font-size: 13px;
-        background-color: rgb(250, 129, 0);
-        font-family: serif;
-        font-style: normal;
-        font-weight: normal;
-        line-height: normal;
-        user-select: none;
-        color: white;
-        padding-left: 2px;
-        padding-right: 2px;
-      }
-      [ychange_state] {
-        position: relative;
-      }
-      [ychange_state]:hover::before {
-        content: attr(ychange_user);
-        background-color: #fa8100;
-        position: absolute;
-        top: -14px;
-        right: 0;
-        font-size: 12px;
-        padding: 0 2px;
-        border-radius: 3px 3px 0 0;
-        color: #fdfdfe;
-        user-select: none;
-        word-break: normal;
-      }
-      *[ychange_state='added'] {
-        background-color: #fa810069;
-      }
-      ychange[ychange_state='removed'] {
-        color: rgb(250, 129, 0);
-        text-decoration: line-through;
-      }
-      *:not(ychange)[ychange_state='removed'] {
-        background-color: #ff9494c9;
-        text-decoration: line-through;
-      }
-      img[ychange_state='removed'] {
-        padding: 2px;
-      }
-    </style>
-</head>
-<body>
-  <p>This example shows how to bind a YXmlFragment type to a <a href="http://prosemirror.net">Prosemirror</a> editor.</p>
-  <p>The content of this editor is shared with every client who visits this domain.</p>
-  <div class="code-html">
-
-<div id="editor" style="margin-bottom: 23px"></div>
-<div style="display: none" id="content"></div>
-  </div>
-  <!-- The actual source file for the following code is found in ./prosemirror.js. Run `npm run watch` to compile the files -->
-  <script class="code-js" src="./build/prosemirror.js" type="module">
-import * as Y from 'yjs'
-import { WebsocketProvider } from 'yjs/provider/websocket.js'
-import { prosemirrorPlugin, cursorPlugin } from 'yjs/bindings/prosemirror'
-
-import * as conf from './exampleConfig.js'
-
-import { EditorState } from 'prosemirror-state'
-import { EditorView } from 'prosemirror-view'
-import { DOMParser } from 'prosemirror-model'
-import { schema } from 'prosemirror-schema-basic'
-import { exampleSetup } from 'prosemirror-example-setup'
-
-const provider = new WebsocketProvider(conf.serverAddress)
-const ydocument = provider.get('prosemirror')
-const type = ydocument.define('prosemirror', Y.XmlFragment)
-
-const prosemirrorView = new EditorView(document.querySelector('#editor'), {
-  state: EditorState.create({
-    doc: DOMParser.fromSchema(schema).parse(document.querySelector('#content')),
-    plugins: exampleSetup({schema}).concat([prosemirrorPlugin(type), cursorPlugin])
-  })
-})
-
-window.example = { provider, ydocument, type, prosemirrorView }
-  </script>
-</body>
-</html>
--- a/examples/prosemirror.js
+++ b/examples/prosemirror.js
@@ -1,25 +0,0 @@
-import * as Y from 'yjs'
-import { WebsocketProvider } from 'y-websocket'
-import { prosemirrorPlugin, cursorPlugin } from 'y-prosemirror'
-
-import * as conf from './exampleConfig.js'
-
-import { EditorState } from 'prosemirror-state'
-import { EditorView } from 'prosemirror-view'
-import { DOMParser } from 'prosemirror-model'
-import { schema } from './prosemirror-schema.js'
-import { exampleSetup } from 'prosemirror-example-setup'
-// import { noteHistoryPlugin } from './prosemirror-history.js'
-
-const provider = new WebsocketProvider(conf.serverAddress)
-const ydocument = provider.get('prosemirror', { gc: false })
-const type = ydocument.define('prosemirror', Y.XmlFragment)
-
-const prosemirrorView = new EditorView(document.querySelector('#editor'), {
-  state: EditorState.create({
-    doc: DOMParser.fromSchema(schema).parse(document.querySelector('#content')),
-    plugins: exampleSetup({ schema }).concat([prosemirrorPlugin(type), cursorPlugin])
-  })
-})
-
-window.example = { provider, ydocument, type, prosemirrorView }
--- a/examples/quill.html
+++ b/examples/quill.html
@@ -1,51 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-    <title>Yjs Quill Example</title>
-    <link rel="stylesheet" href="https://cdn.quilljs.com/1.3.6/quill.snow.css">
-  </head>
-<body>
-  <p>This example shows how to bind a YText type to <a href="https://quilljs.com">Quill</a> editor.</p>
-  <p>The content of this editor is shared with every client who visits this domain.</p>
-  <div class="code-html">
-<div id="quill-container">
-  <div id="quill">
-  </div>
-</div>
-  </div>
-  <!-- The actual source file for the following code is found in ./quill.js. Run `npm run watch` to compile the files -->
-  <script class="code-js" src="./build/quill.js" type="module">
-import * as Y from 'yjs'
-import { WebsocketProvider } from 'yjs/provider/websocket.js'
-import { QuillBinding } from 'yjs/bindings/quill.js'
-
-import * as conf from './exampleConfig.js'
-
-import Quill from 'quill'
-
-const provider = new WebsocketProvider(conf.serverAddress)
-const ydocument = provider.get('quill')
-const ytext = ydocument.define('quill', Y.Text)
-
-const quill = new Quill('#quill-container', {
-  modules: {
-    toolbar: [
-      [{ header: [1, 2, false] }],
-      ['bold', 'italic', 'underline'],
-      ['image', 'code-block'],
-      [{ color: [] }, { background: [] }], // Snow theme fills in values
-      [{ script: 'sub' }, { script: 'super' }],
-      ['link', 'image'],
-      ['link', 'code-block'],
-      [{ list: 'ordered' }, { list: 'bullet' }]
-    ]
-  },
-  placeholder: 'Compose an epic...',
-  theme: 'snow' // or 'bubble'
-})
-
-window.quillBinding = new QuillBinding(ytext, quill)
-
-  </script>
-</body>
-</html>
--- a/examples/quill.js
+++ b/examples/quill.js
@@ -1,30 +0,0 @@
-import * as Y from '../src/index.js'
-import { WebsocketProvider } from 'y-websocket'
-import { QuillBinding } from 'y-quill'
-
-import * as conf from './exampleConfig.js'
-
-import Quill from 'quill'
-
-const provider = new WebsocketProvider(conf.serverAddress)
-const ydocument = provider.get('quill')
-const ytext = ydocument.define('quill', Y.Text)
-
-const quill = new Quill('#quill-container', {
-  modules: {
-    toolbar: [
-      [{ header: [1, 2, false] }],
-      ['bold', 'italic', 'underline'],
-      ['image', 'code-block'],
-      [{ color: [] }, { background: [] }], // Snow theme fills in values
-      [{ script: 'sub' }, { script: 'super' }],
-      ['link', 'image'],
-      ['link', 'code-block'],
-      [{ list: 'ordered' }, { list: 'bullet' }]
-    ]
-  },
-  placeholder: 'Compose an epic...',
-  theme: 'snow' // or 'bubble'
-})
-
-window.quillBinding = new QuillBinding(ytext, quill)
--- a/examples/style.css
+++ b/examples/style.css
@@ -1,29 +0,0 @@
-footer img {
-  display: none;
-}
-
-nav .title h1 a {
-  display: none;
-}
-
-footer {
-  background-color: #b93c1d;
-}
-
-#resizer {
-  background-color: #b93c1d;
-}
-
-.main section article.readme h1:first-child img {
-  display: none;
-}
-
-.main section article.readme h1:first-child {
-  margin-bottom: 16px;
-  margin-top: 30px;
-}
-
-.main section article.readme h1:first-child::before {
-  content: "Yjs";
-  font-size: 2em;
-}
--- a/examples/textarea.html
+++ b/examples/textarea.html
@@ -1,32 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-    <title>Yjs Textarea Example</title>
-</head>
-<body>
-  <p>This example shows how to bind a YText type to a DOM Textarea.</p>
-  <p>The content of this textarea is shared with every client who visits this domain.</p>
-  <div class="code-html">
-
-<textarea style="width:80%;" rows=40 autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false"></textarea>
-  </div>
-  <!-- The actual source file for the following code is found in ./textarea.js. Run `npm run watch` to compile the files -->
-  <script class="code-js" src="./build/textarea.js" type="module">
-import * as Y from 'yjs'
-import { WebsocketProvider } from 'yjs/provider/websocket.js'
-import { TextareaBinding } from 'yjs/bindings/textarea.js'
-
-import * as conf from './exampleConfig.js'
-
-const provider = new WebsocketProvider(conf.serverAddress)
-const ydocument = provider.get('textarea')
-const type = ydocument.define('textarea', Y.Text)
-const textarea = document.querySelector('textarea')
-const binding = new TextareaBinding(type, textarea)
-
-window.textareaExample = {
-  provider, ydocument, type, textarea, binding
-}
-  </script>
-</body>
-</html>
--- a/examples/textarea.js
+++ b/examples/textarea.js
@@ -1,14 +0,0 @@
-import { WebsocketProvider } from 'y-websocket'
-import { TextareaBinding } from 'y-textarea'
-
-import * as conf from './exampleConfig.js'
-
-const provider = new WebsocketProvider(conf.serverAddress)
-const ydocument = provider.get('textarea')
-const type = ydocument.getText('textarea')
-const textarea = document.querySelector('textarea')
-const binding = new TextareaBinding(type, textarea)
-
-window.textareaExample = {
-  provider, ydocument, type, textarea, binding
-}
--- a/package-lock.json
+++ b/package-lock.json
--- a/package.json
+++ b/package.json
@@ -1,41 +1,39 @@
 {
  "name": "yjs",
-  "version": "13.0.0-78",
-  "description": "A ",
+  "version": "13.0.0-96",
+  "description": "Shared Editing Library",
  "main": "./dist/yjs.js",
-  "module": "./dist/yjs.mjs'",
+  "module": "./dist/yjs.mjs",
  "sideEffects": false,
  "scripts": {
    "test": "npm run dist && PRODUCTION=1 node ./dist/tests.js --repitition-time 50 --production",
    "test-exhaustive": "npm run lint && npm run dist && node ./dist/tests.js --repitition-time 10000",
-    "dist": "rm -rf dist examples/build && rollup -c",
+    "dist": "rm -rf dist && rollup -c",
    "watch": "rollup -wc",
-    "lint": "standard && tsc",
+    "lint": "markdownlint README.v13.md && standard && tsc",
    "docs": "rm -rf docs; jsdoc --configure ./.jsdoc.json --verbose --readme ./README.v13.md --package ./package.json || true",
    "serve-docs": "npm run docs && serve ./docs/",
-    "postversion": "npm run lint && PRODUCTION=1 npm run dist && node ./dist/tests.js --repitition-time 1000",
+    "preversion": "npm run lint && PRODUCTION=1 npm run dist && npm run docs && node ./dist/tests.js --repitition-time 1000",
+    "postversion": "git push && git push --tags",
    "debug": "concurrently 'live-server --port=3443 --entry-file=test.html' 'npm run watch'",
    "trace-deopt": "clear && rollup -c  && node --trace-deopt dist/test.js",
    "trace-opt": "clear && rollup -c  && node --trace-opt dist/test.js"
  },
  "files": [
    "dist/*",
-    "examples/*",
-    "docs/*",
-    "README.md",
-    "LICENSE"
+    "src/*",
+    "tests/*",
+    "docs/*"
  ],
  "dictionaries": {
    "doc": "docs",
-    "example": "examples",
    "test": "tests"
  },
  "standard": {
    "ignore": [
      "/dist",
      "/node_modules",
-      "/docs",
-      "/examples/build"
+      "/docs"
    ]
  },
  "repository": {
@@ -53,28 +51,18 @@
  },
  "homepage": "http://y-js.org",
  "dependencies": {
-    "lib0": "0.0.0"
+    "lib0": "0.0.6"
  },
  "devDependencies": {
-    "codemirror": "^5.42.0",
    "concurrently": "^3.6.1",
-    "esdoc": "^1.1.0",
-    "esdoc-standard-plugin": "^1.0.0",
-    "jsdoc": "^3.5.5",
+    "jsdoc": "^3.6.3",
    "live-server": "^1.2.1",
-    "prosemirror-example-setup": "^1.0.1",
-    "prosemirror-schema-basic": "^1.0.0",
-    "prosemirror-state": "^1.2.2",
-    "prosemirror-view": "^1.6.5",
-    "quill": "^1.3.6",
-    "quill-cursors": "^1.0.3",
-    "rollup": "^1.1.2",
+    "rollup": "^1.11.3",
    "rollup-cli": "^1.0.9",
-    "rollup-plugin-commonjs": "^9.2.0",
-    "rollup-plugin-node-resolve": "^4.0.0",
-    "rollup-plugin-terser": "^4.0.4",
+    "rollup-plugin-node-resolve": "^4.2.4",
    "standard": "^11.0.1",
    "tui-jsdoc-template": "^1.2.2",
-    "typescript": "^3.3.3333"
+    "typescript": "^3.4.5",
+    "y-protocols": "0.0.6"
  }
 }
--- a/rollup.config.js
+++ b/rollup.config.js
@@ -1,6 +1,6 @@
 import nodeResolve from 'rollup-plugin-node-resolve'
-import commonjs from 'rollup-plugin-commonjs'
-import { terser } from 'rollup-plugin-terser'
+
+const localImports = process.env.LOCALIMPORTS

 const customModules = new Set([
  'y-websocket',
@@ -23,31 +23,18 @@ const debugResolve = {
    if (importee === 'yjs') {
      return `${process.cwd()}/src/index.js`
    }
-    if (customModules.has(importee.split('/')[0])) {
-      return `${process.cwd()}/../${importee}/src/${importee}.js`
-    }
-    if (customLibModules.has(importee.split('/')[0])) {
-      return `${process.cwd()}/../${importee}`
+    if (localImports) {
+      if (customModules.has(importee.split('/')[0])) {
+        return `${process.cwd()}/../${importee}/src/${importee}.js`
+      }
+      if (customLibModules.has(importee.split('/')[0])) {
+        return `${process.cwd()}/../${importee}`
+      }
    }
    return null
  }
 }

-const minificationPlugins = process.env.PRODUCTION ? [terser({
-  module: true,
-  compress: {
-    hoist_vars: true,
-    module: true,
-    passes: 5,
-    pure_getters: true,
-    unsafe_comps: true,
-    unsafe_undefined: true
-  },
-  mangle: {
-    toplevel: true
-  }
-})] : []
-
 export default [{
  input: './src/index.js',
  output: [{
@@ -80,26 +67,7 @@ export default [{
    debugResolve,
    nodeResolve({
      sourcemap: true,
-      module: true,
-      browser: true
-    }),
-    commonjs()
-  ]
-}, {
-  input: ['./examples/codemirror.js', './examples/textarea.js'], // './examples/quill.js', './examples/dom.js', './examples/prosemirror.js'
-  output: {
-    dir: 'examples/build',
-    format: 'esm',
-    sourcemap: true
-  },
-  plugins: [
-    debugResolve,
-    nodeResolve({
-      sourcemap: true,
-      module: true,
-      browser: true
-    }),
-    commonjs(),
-    ...minificationPlugins
+      mainFields: ['module', 'browser', 'main']
+    })
  ]
 }]
--- a/src/index.js
+++ b/src/index.js
@@ -1,6 +1,6 @@

 export {
-  Y,
+  Doc,
  Transaction,
  YArray as Array,
  YMap as Map,
@@ -9,18 +9,40 @@ export {
  YXmlHook as XmlHook,
  YXmlElement as XmlElement,
  YXmlFragment as XmlFragment,
-  createCursorFromTypeOffset,
-  createCursorFromJSON,
-  createAbsolutePositionFromCursor,
-  writeCursor,
-  readCursor,
+  YXmlEvent,
+  YMapEvent,
+  YArrayEvent,
+  YEvent,
+  Item,
+  AbstractStruct,
+  GC,
+  ContentBinary,
+  ContentDeleted,
+  ContentEmbed,
+  ContentFormat,
+  ContentJSON,
+  ContentAny,
+  ContentString,
+  ContentType,
+  AbstractType,
+  RelativePosition,
+  createRelativePositionFromTypeIndex,
+  createRelativePositionFromJSON,
+  createAbsolutePositionFromRelativePosition,
+  compareRelativePositions,
+  writeRelativePosition,
+  readRelativePosition,
  ID,
  createID,
  compareIDs,
  getState,
-  getStates,
-  readStatesAsMap,
-  writeStates,
-  writeModel,
-  readModel
+  Snapshot,
+  findRootTypeKey,
+  typeListToArraySnapshot,
+  typeMapGetSnapshot,
+  iterateDeletedStructs,
+  applyUpdate,
+  encodeStateAsUpdate,
+  encodeStateVector,
+  UndoManager
 } from './internals.js'
--- a/src/internals.js
+++ b/src/internals.js
@@ -2,32 +2,34 @@ export * from './utils/DeleteSet.js'
 export * from './utils/EventHandler.js'
 export * from './utils/ID.js'
 export * from './utils/isParentOf.js'
-export * from './utils/cursor.js'
+export * from './utils/RelativePosition.js'
 export * from './utils/Snapshot.js'
 export * from './utils/StructStore.js'
 export * from './utils/Transaction.js'
-// export * from './utils/UndoManager.js'
-export * from './utils/Y.js'
+export * from './utils/UndoManager.js'
+export * from './utils/Doc.js'
 export * from './utils/YEvent.js'

 export * from './types/AbstractType.js'
 export * from './types/YArray.js'
 export * from './types/YMap.js'
 export * from './types/YText.js'
+export * from './types/YXmlFragment.js'
 export * from './types/YXmlElement.js'
 export * from './types/YXmlEvent.js'
 export * from './types/YXmlHook.js'
 export * from './types/YXmlText.js'

 export * from './structs/AbstractStruct.js'
-export * from './structs/AbstractItem.js'
 export * from './structs/GC.js'
-export * from './structs/ItemBinary.js'
-export * from './structs/ItemDeleted.js'
-export * from './structs/ItemEmbed.js'
-export * from './structs/ItemFormat.js'
-export * from './structs/ItemJSON.js'
-export * from './structs/ItemString.js'
-export * from './structs/ItemType.js'
+export * from './structs/ContentBinary.js'
+export * from './structs/ContentDeleted.js'
+export * from './structs/ContentEmbed.js'
+export * from './structs/ContentFormat.js'
+export * from './structs/ContentJSON.js'
+export * from './structs/ContentAny.js'
+export * from './structs/ContentString.js'
+export * from './structs/ContentType.js'
+export * from './structs/Item.js'

 export * from './utils/encoding.js'
--- a/src/structs/AbstractStruct.js
+++ b/src/structs/AbstractStruct.js
@@ -1,6 +1,6 @@

 import {
-  Y, StructStore, ID, Transaction // eslint-disable-line
+  StructStore, ID, Transaction // eslint-disable-line
 } from '../internals.js'

 import * as encoding from 'lib0/encoding.js' // eslint-disable-line
@@ -12,14 +12,16 @@ import * as error from 'lib0/error.js'
 export class AbstractStruct {
  /**
   * @param {ID} id
+   * @param {number} length
   */
-  constructor (id) {
+  constructor (id, length) {
    /**
     * The uniqe identifier of this struct.
     * @type {ID}
     * @readonly
     */
    this.id = id
+    this.length = length
    this.deleted = false
  }
  /**
@@ -32,12 +34,6 @@ export class AbstractStruct {
  mergeWith (right) {
    return false
  }
-  /**
-   * @type {number}
-   */
-  get length () {
-    throw error.methodUnimplemented()
-  }
  /**
   * @param {encoding.Encoder} encoder The encoder to write data to.
   * @param {number} offset
@@ -89,10 +85,4 @@ export class AbstractStructRef {
  toStruct (transaction, store, offset) {
    throw error.methodUnimplemented()
  }
-  /**
-   * @type {number}
-   */
-  get length () {
-    return 1
-  }
 }
--- a/src/structs/ContentAny.js
+++ b/src/structs/ContentAny.js
@@ -0,0 +1,108 @@
+import {
+  Transaction, Item, StructStore // eslint-disable-line
+} from '../internals.js'
+
+import * as encoding from 'lib0/encoding.js'
+import * as decoding from 'lib0/decoding.js'
+
+/**
+ * @private
+ */
+export class ContentAny {
+  /**
+   * @param {Array<any>} arr
+   */
+  constructor (arr) {
+    /**
+     * @type {Array<any>}
+     */
+    this.arr = arr
+  }
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return this.arr.length
+  }
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return this.arr
+  }
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return true
+  }
+  /**
+   * @return {ContentAny}
+   */
+  copy () {
+    return new ContentAny(this.arr)
+  }
+  /**
+   * @param {number} offset
+   * @return {ContentAny}
+   */
+  splice (offset) {
+    const right = new ContentAny(this.arr.slice(offset))
+    this.arr = this.arr.slice(0, offset)
+    return right
+  }
+  /**
+   * @param {ContentAny} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    this.arr = this.arr.concat(right.arr)
+    return true
+  }
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {}
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {}
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+  /**
+   * @param {encoding.Encoder} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    const len = this.arr.length
+    encoding.writeVarUint(encoder, len - offset)
+    for (let i = offset; i < len; i++) {
+      const c = this.arr[i]
+      encoding.writeAny(encoder, c)
+    }
+  }
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 8
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {decoding.Decoder} decoder
+ * @return {ContentAny}
+ */
+export const readContentAny = decoder => {
+  const len = decoding.readVarUint(decoder)
+  const cs = []
+  for (let i = 0; i < len; i++) {
+    cs.push(decoding.readAny(decoder))
+  }
+  return new ContentAny(cs)
+}
--- a/src/structs/ContentBinary.js
+++ b/src/structs/ContentBinary.js
@@ -0,0 +1,92 @@
+import {
+  StructStore, Item, Transaction // eslint-disable-line
+} from '../internals.js'
+
+import * as encoding from 'lib0/encoding.js'
+import * as decoding from 'lib0/decoding.js'
+import * as buffer from 'lib0/buffer.js'
+import * as error from 'lib0/error.js'
+
+/**
+ * @private
+ */
+export class ContentBinary {
+  /**
+   * @param {Uint8Array} content
+   */
+  constructor (content) {
+    this.content = content
+  }
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return 1
+  }
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return [this.content]
+  }
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return true
+  }
+  /**
+   * @return {ContentBinary}
+   */
+  copy () {
+    return new ContentBinary(this.content)
+  }
+  /**
+   * @param {number} offset
+   * @return {ContentBinary}
+   */
+  splice (offset) {
+    throw error.methodUnimplemented()
+  }
+  /**
+   * @param {ContentBinary} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    return false
+  }
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {}
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {}
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+  /**
+   * @param {encoding.Encoder} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    encoding.writeVarUint8Array(encoder, this.content)
+  }
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 3
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {decoding.Decoder} decoder
+ * @return {ContentBinary}
+ */
+export const readContentBinary = decoder => new ContentBinary(buffer.copyUint8Array(decoding.readVarUint8Array(decoder)))
--- a/src/structs/ContentDeleted.js
+++ b/src/structs/ContentDeleted.js
@@ -0,0 +1,98 @@
+
+import {
+  addToDeleteSet,
+  StructStore, Item, Transaction // eslint-disable-line
+} from '../internals.js'
+
+import * as encoding from 'lib0/encoding.js'
+import * as decoding from 'lib0/decoding.js'
+
+/**
+ * @private
+ */
+export class ContentDeleted {
+  /**
+   * @param {number} len
+   */
+  constructor (len) {
+    this.len = len
+  }
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return this.len
+  }
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return []
+  }
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return false
+  }
+  /**
+   * @return {ContentDeleted}
+   */
+  copy () {
+    return new ContentDeleted(this.len)
+  }
+  /**
+   * @param {number} offset
+   * @return {ContentDeleted}
+   */
+  splice (offset) {
+    const right = new ContentDeleted(this.len - offset)
+    this.len = offset
+    return right
+  }
+  /**
+   * @param {ContentDeleted} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    this.len += right.len
+    return true
+  }
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {
+    addToDeleteSet(transaction.deleteSet, item.id, this.len)
+    item.deleted = true
+  }
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {}
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+  /**
+   * @param {encoding.Encoder} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    encoding.writeVarUint(encoder, this.len - offset)
+  }
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 1
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {decoding.Decoder} decoder
+ * @return {ContentDeleted}
+ */
+export const readContentDeleted = decoder => new ContentDeleted(decoding.readVarUint(decoder))
--- a/src/structs/ContentEmbed.js
+++ b/src/structs/ContentEmbed.js
@@ -0,0 +1,92 @@
+
+import {
+  StructStore, Item, Transaction // eslint-disable-line
+} from '../internals.js'
+
+import * as encoding from 'lib0/encoding.js'
+import * as decoding from 'lib0/decoding.js'
+import * as error from 'lib0/error.js'
+
+/**
+ * @private
+ */
+export class ContentEmbed {
+  /**
+   * @param {Object} embed
+   */
+  constructor (embed) {
+    this.embed = embed
+  }
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return 1
+  }
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return [this.embed]
+  }
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return true
+  }
+  /**
+   * @return {ContentEmbed}
+   */
+  copy () {
+    return new ContentEmbed(this.embed)
+  }
+  /**
+   * @param {number} offset
+   * @return {ContentEmbed}
+   */
+  splice (offset) {
+    throw error.methodUnimplemented()
+  }
+  /**
+   * @param {ContentEmbed} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    return false
+  }
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {}
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {}
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+  /**
+   * @param {encoding.Encoder} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    encoding.writeVarString(encoder, JSON.stringify(this.embed))
+  }
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 5
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {decoding.Decoder} decoder
+ * @return {ContentEmbed}
+ */
+export const readContentEmbed = decoder => new ContentEmbed(JSON.parse(decoding.readVarString(decoder)))
--- a/src/structs/ContentFormat.js
+++ b/src/structs/ContentFormat.js
@@ -0,0 +1,95 @@
+
+import {
+  Item, StructStore, Transaction // eslint-disable-line
+} from '../internals.js'
+
+import * as encoding from 'lib0/encoding.js'
+import * as decoding from 'lib0/decoding.js'
+import * as error from 'lib0/error.js'
+
+/**
+ * @private
+ */
+export class ContentFormat {
+  /**
+   * @param {string} key
+   * @param {Object} value
+   */
+  constructor (key, value) {
+    this.key = key
+    this.value = value
+  }
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return 1
+  }
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return []
+  }
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return false
+  }
+  /**
+   * @return {ContentFormat}
+   */
+  copy () {
+    return new ContentFormat(this.key, this.value)
+  }
+  /**
+   * @param {number} offset
+   * @return {ContentFormat}
+   */
+  splice (offset) {
+    throw error.methodUnimplemented()
+  }
+  /**
+   * @param {ContentFormat} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    return false
+  }
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {}
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {}
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+  /**
+   * @param {encoding.Encoder} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    encoding.writeVarString(encoder, this.key)
+    encoding.writeVarString(encoder, JSON.stringify(this.value))
+  }
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 6
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {decoding.Decoder} decoder
+ * @return {ContentFormat}
+ */
+export const readContentFormat = decoder => new ContentFormat(decoding.readVarString(decoder), JSON.parse(decoding.readVarString(decoder)))
--- a/src/structs/ContentJSON.js
+++ b/src/structs/ContentJSON.js
@@ -0,0 +1,113 @@
+import {
+  Transaction, Item, StructStore // eslint-disable-line
+} from '../internals.js'
+
+import * as encoding from 'lib0/encoding.js'
+import * as decoding from 'lib0/decoding.js'
+
+/**
+ * @private
+ */
+export class ContentJSON {
+  /**
+   * @param {Array<any>} arr
+   */
+  constructor (arr) {
+    /**
+     * @type {Array<any>}
+     */
+    this.arr = arr
+  }
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return this.arr.length
+  }
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return this.arr
+  }
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return true
+  }
+  /**
+   * @return {ContentJSON}
+   */
+  copy () {
+    return new ContentJSON(this.arr)
+  }
+  /**
+   * @param {number} offset
+   * @return {ContentJSON}
+   */
+  splice (offset) {
+    const right = new ContentJSON(this.arr.slice(offset))
+    this.arr = this.arr.slice(0, offset)
+    return right
+  }
+  /**
+   * @param {ContentJSON} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    this.arr = this.arr.concat(right.arr)
+    return true
+  }
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {}
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {}
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+  /**
+   * @param {encoding.Encoder} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    const len = this.arr.length
+    encoding.writeVarUint(encoder, len - offset)
+    for (let i = offset; i < len; i++) {
+      const c = this.arr[i]
+      encoding.writeVarString(encoder, c === undefined ? 'undefined' : JSON.stringify(c))
+    }
+  }
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 2
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {decoding.Decoder} decoder
+ * @return {ContentJSON}
+ */
+export const readContentJSON = decoder => {
+  const len = decoding.readVarUint(decoder)
+  const cs = []
+  for (let i = 0; i < len; i++) {
+    const c = decoding.readVarString(decoder)
+    if (c === 'undefined') {
+      cs.push(undefined)
+    } else {
+      cs.push(JSON.parse(c))
+    }
+  }
+  return new ContentJSON(cs)
+}
--- a/src/structs/ContentString.js
+++ b/src/structs/ContentString.js
@@ -0,0 +1,96 @@
+import {
+  Transaction, Item, StructStore // eslint-disable-line
+} from '../internals.js'
+
+import * as encoding from 'lib0/encoding.js'
+import * as decoding from 'lib0/decoding.js'
+
+/**
+ * @private
+ */
+export class ContentString {
+  /**
+   * @param {string} str
+   */
+  constructor (str) {
+    /**
+     * @type {string}
+     */
+    this.str = str
+  }
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return this.str.length
+  }
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return this.str.split('')
+  }
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return true
+  }
+  /**
+   * @return {ContentString}
+   */
+  copy () {
+    return new ContentString(this.str)
+  }
+  /**
+   * @param {number} offset
+   * @return {ContentString}
+   */
+  splice (offset) {
+    const right = new ContentString(this.str.slice(offset))
+    this.str = this.str.slice(0, offset)
+    return right
+  }
+  /**
+   * @param {ContentString} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    this.str += right.str
+    return true
+  }
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {}
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {}
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+  /**
+   * @param {encoding.Encoder} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    encoding.writeVarString(encoder, offset === 0 ? this.str : this.str.slice(offset))
+  }
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 4
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {decoding.Decoder} decoder
+ * @return {ContentString}
+ */
+export const readContentString = decoder => new ContentString(decoding.readVarString(decoder))
--- a/src/structs/ContentType.js
+++ b/src/structs/ContentType.js
@@ -0,0 +1,163 @@
+
+import {
+  readYArray,
+  readYMap,
+  readYText,
+  readYXmlElement,
+  readYXmlFragment,
+  readYXmlHook,
+  readYXmlText,
+  StructStore, Transaction, Item, YEvent, AbstractType // eslint-disable-line
+} from '../internals.js'
+
+import * as encoding from 'lib0/encoding.js' // eslint-disable-line
+import * as decoding from 'lib0/decoding.js'
+import * as error from 'lib0/error.js'
+
+/**
+ * @type {Array<function(decoding.Decoder):AbstractType<any>>}
+ * @private
+ */
+export const typeRefs = [
+  readYArray,
+  readYMap,
+  readYText,
+  readYXmlElement,
+  readYXmlFragment,
+  readYXmlHook,
+  readYXmlText
+]
+
+export const YArrayRefID = 0
+export const YMapRefID = 1
+export const YTextRefID = 2
+export const YXmlElementRefID = 3
+export const YXmlFragmentRefID = 4
+export const YXmlHookRefID = 5
+export const YXmlTextRefID = 6
+
+/**
+ * @private
+ */
+export class ContentType {
+  /**
+   * @param {AbstractType<YEvent>} type
+   */
+  constructor (type) {
+    /**
+     * @type {AbstractType<any>}
+     */
+    this.type = type
+  }
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return 1
+  }
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return [this.type]
+  }
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return true
+  }
+  /**
+   * @return {ContentType}
+   */
+  copy () {
+    return new ContentType(this.type._copy())
+  }
+  /**
+   * @param {number} offset
+   * @return {ContentType}
+   */
+  splice (offset) {
+    throw error.methodUnimplemented()
+  }
+  /**
+   * @param {ContentType} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    return false
+  }
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {
+    this.type._integrate(transaction.doc, item)
+  }
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {
+    let item = this.type._start
+    while (item !== null) {
+      if (!item.deleted) {
+        item.delete(transaction)
+      } else {
+        // Whis will be gc'd later and we want to merge it if possible
+        // We try to merge all deleted items after each transaction,
+        // but we have no knowledge about that this needs to be merged
+        // since it is not in transaction.ds. Hence we add it to transaction._mergeStructs
+        transaction._mergeStructs.add(item.id)
+      }
+      item = item.right
+    }
+    this.type._map.forEach(item => {
+      if (!item.deleted) {
+        item.delete(transaction)
+      } else {
+        // same as above
+        transaction._mergeStructs.add(item.id)
+      }
+    })
+    transaction.changed.delete(this.type)
+  }
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {
+    let item = this.type._start
+    while (item !== null) {
+      item.gc(store, true)
+      item = item.right
+    }
+    this.type._start = null
+    this.type._map.forEach(/** @param {Item | null} item */ (item) => {
+      while (item !== null) {
+        item.gc(store, true)
+        item = item.left
+      }
+    })
+    this.type._map = new Map()
+  }
+  /**
+   * @param {encoding.Encoder} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    this.type._write(encoder)
+  }
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 7
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {decoding.Decoder} decoder
+ * @return {ContentType}
+ */
+export const readContentType = decoder => new ContentType(typeRefs[decoding.readVarUint(decoder)](decoder))
--- a/src/structs/GC.js
+++ b/src/structs/GC.js
@@ -4,7 +4,7 @@ import {
  AbstractStruct,
  createID,
  addStruct,
-  Y, StructStore, Transaction, ID // eslint-disable-line
+  StructStore, Transaction, ID // eslint-disable-line
 } from '../internals.js'

 import * as decoding from 'lib0/decoding.js'
@@ -21,26 +21,18 @@ export class GC extends AbstractStruct {
   * @param {number} length
   */
  constructor (id, length) {
-    super(id)
-    /**
-     * @type {number}
-     */
-    this._len = length
+    super(id, length)
    this.deleted = true
  }

-  get length () {
-    return this._len
-  }
-
  delete () {}

  /**
-   * @param {AbstractStruct} right
+   * @param {GC} right
   * @return {boolean}
   */
  mergeWith (right) {
-    this._len += right.length
+    this.length += right.length
    return true
  }

@@ -48,7 +40,7 @@ export class GC extends AbstractStruct {
   * @param {Transaction} transaction
   */
  integrate (transaction) {
-    addStruct(transaction.y.store, this)
+    addStruct(transaction.doc.store, this)
  }

  /**
@@ -57,7 +49,7 @@ export class GC extends AbstractStruct {
   */
  write (encoder, offset) {
    encoding.writeUint8(encoder, structGCRefNumber)
-    encoding.writeVarUint(encoder, this._len - offset)
+    encoding.writeVarUint(encoder, this.length - offset)
  }
 }

@@ -75,15 +67,7 @@ export class GCRef extends AbstractStructRef {
    /**
     * @type {number}
     */
-    this._len = decoding.readVarUint(decoder)
-  }
-  get length () {
-    return this._len
-  }
-  missing () {
-    return [
-      createID(this.id.client, this.id.clock - 1)
-    ]
+    this.length = decoding.readVarUint(decoder)
  }
  /**
   * @param {Transaction} transaction
@@ -95,11 +79,11 @@ export class GCRef extends AbstractStructRef {
    if (offset > 0) {
      // @ts-ignore
      this.id = createID(this.id.client, this.id.clock + offset)
-      this._len = this._len - offset
+      this.length -= offset
    }
    return new GC(
      this.id,
-      this._len
+      this.length
    )
  }
 }
--- a/src/structs/AbstractItem.js
+++ b/src/structs/AbstractItem.js
@@ -10,14 +10,21 @@ import {
  replaceStruct,
  addStruct,
  addToDeleteSet,
-  ItemDeleted,
  findRootTypeKey,
  compareIDs,
  getItem,
-  getItemType,
  getItemCleanEnd,
  getItemCleanStart,
-  YEvent, StructStore, ID, AbstractType, Y, Transaction // eslint-disable-line
+  readContentDeleted,
+  readContentBinary,
+  readContentJSON,
+  readContentAny,
+  readContentString,
+  readContentEmbed,
+  readContentFormat,
+  readContentType,
+  addChangedTypeToTransaction,
+  ContentType, ContentDeleted, StructStore, ID, AbstractType, Transaction // eslint-disable-line
 } from '../internals.js'

 import * as error from 'lib0/error.js'
@@ -27,12 +34,52 @@ import * as maplib from 'lib0/map.js'
 import * as set from 'lib0/set.js'
 import * as binary from 'lib0/binary.js'

+/**
+ * @param {StructStore} store
+ * @param {ID} id
+ * @return {{item:Item, diff:number}}
+ */
+export const followRedone = (store, id) => {
+  /**
+   * @type {ID|null}
+   */
+  let nextID = id
+  let diff = 0
+  let item
+  do {
+    if (diff > 0) {
+      nextID = createID(nextID.client, nextID.clock + diff)
+    }
+    item = getItem(store, nextID)
+    diff = nextID.clock - item.id.clock
+    nextID = item.redone
+  } while (nextID !== null)
+  return {
+    item, diff
+  }
+}
+
+/**
+ * Make sure that neither item nor any of its parents is ever deleted.
+ *
+ * This property does not persist when storing it into a database or when
+ * sending it to other peers
+ *
+ * @param {Item|null} item
+ */
+export const keepItem = item => {
+  while (item !== null && !item.keep) {
+    item.keep = true
+    item = item.parent._item
+  }
+}
+
 /**
 * Split leftItem into two items
 * @param {Transaction} transaction
- * @param {AbstractItem} leftItem
+ * @param {Item} leftItem
 * @param {number} diff
- * @return {AbstractItem}
+ * @return {Item}
 *
 * @function
 * @private
@@ -40,18 +87,25 @@ import * as binary from 'lib0/binary.js'
 export const splitItem = (transaction, leftItem, diff) => {
  const id = leftItem.id
  // create rightItem
-  const rightItem = leftItem.copy(
+  const rightItem = new Item(
    createID(id.client, id.clock + diff),
    leftItem,
    createID(id.client, id.clock + diff - 1),
    leftItem.right,
    leftItem.rightOrigin,
    leftItem.parent,
-    leftItem.parentSub
+    leftItem.parentSub,
+    leftItem.content.splice(diff)
  )
  if (leftItem.deleted) {
    rightItem.deleted = true
  }
+  if (leftItem.keep) {
+    rightItem.keep = true
+  }
+  if (leftItem.redone !== null) {
+    rightItem.redone = createID(leftItem.redone.client, leftItem.redone.clock + diff)
+  }
  // update left (do not set leftItem.rightOrigin as it will lead to problems when syncing)
  leftItem.right = rightItem
  // update right
@@ -60,24 +114,131 @@ export const splitItem = (transaction, leftItem, diff) => {
  }
  // right is more specific.
  transaction._mergeStructs.add(rightItem.id)
+  // update parent._map
+  if (rightItem.parentSub !== null && rightItem.right === null) {
+    rightItem.parent._map.set(rightItem.parentSub, rightItem)
+  }
+  leftItem.length = diff
  return rightItem
 }

+/**
+ * Redoes the effect of this operation.
+ *
+ * @param {Transaction} transaction The Yjs instance.
+ * @param {Item} item
+ * @param {Set<Item>} redoitems
+ *
+ * @return {Item|null}
+ *
+ * @private
+ */
+export const redoItem = (transaction, item, redoitems) => {
+  if (item.redone !== null) {
+    return getItemCleanStart(transaction, transaction.doc.store, item.redone)
+  }
+  let parentItem = item.parent._item
+  /**
+   * @type {Item|null}
+   */
+  let left
+  /**
+   * @type {Item|null}
+   */
+  let right
+  if (item.parentSub === null) {
+    // Is an array item. Insert at the old position
+    left = item.left
+    right = item
+  } else {
+    // Is a map item. Insert as current value
+    left = item
+    while (left.right !== null) {
+      left = left.right
+      if (left.id.client !== transaction.doc.clientID) {
+        // It is not possible to redo this item because it conflicts with a
+        // change from another client
+        return null
+      }
+    }
+    if (left.right !== null) {
+      left = /** @type {Item} */ (item.parent._map.get(item.parentSub))
+    }
+    right = null
+  }
+  // make sure that parent is redone
+  if (parentItem !== null && parentItem.deleted === true && parentItem.redone === null) {
+    // try to undo parent if it will be undone anyway
+    if (!redoitems.has(parentItem) || redoItem(transaction, parentItem, redoitems) === null) {
+      return null
+    }
+  }
+  if (parentItem !== null && parentItem.redone !== null) {
+    while (parentItem.redone !== null) {
+      parentItem = getItemCleanStart(transaction, transaction.doc.store, parentItem.redone)
+    }
+    // find next cloned_redo items
+    while (left !== null) {
+      /**
+       * @type {Item|null}
+       */
+      let leftTrace = left
+      // trace redone until parent matches
+      while (leftTrace !== null && leftTrace.parent._item !== parentItem) {
+        leftTrace = leftTrace.redone === null ? null : getItemCleanStart(transaction, transaction.doc.store, leftTrace.redone)
+      }
+      if (leftTrace !== null && leftTrace.parent._item === parentItem) {
+        left = leftTrace
+        break
+      }
+      left = left.left
+    }
+    while (right !== null) {
+      /**
+       * @type {Item|null}
+       */
+      let rightTrace = right
+      // trace redone until parent matches
+      while (rightTrace !== null && rightTrace.parent._item !== parentItem) {
+        rightTrace = rightTrace.redone === null ? null : getItemCleanStart(transaction, transaction.doc.store, rightTrace.redone)
+      }
+      if (rightTrace !== null && rightTrace.parent._item === parentItem) {
+        right = rightTrace
+        break
+      }
+      right = right.right
+    }
+  }
+  const redoneItem = new Item(
+    nextID(transaction),
+    left, left === null ? null : left.lastId,
+    right, right === null ? null : right.id,
+    parentItem === null ? item.parent : /** @type {ContentType} */ (parentItem.content).type,
+    item.parentSub,
+    item.content.copy()
+  )
+  item.redone = redoneItem.id
+  keepItem(redoneItem)
+  redoneItem.integrate(transaction)
+  return redoneItem
+}
+
 /**
 * Abstract class that represents any content.
 */
-export class AbstractItem extends AbstractStruct {
+export class Item extends AbstractStruct {
  /**
   * @param {ID} id
-   * @param {AbstractItem | null} left
+   * @param {Item | null} left
   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
+   * @param {Item | null} right
   * @param {ID | null} rightOrigin
   * @param {AbstractType<any>} parent
   * @param {string | null} parentSub
+   * @param {AbstractContent} content
   */
-  constructor (id, left, origin, right, rightOrigin, parent, parentSub) {
-    super(id)
+  constructor (id, left, origin, right, rightOrigin, parent, parentSub, content) {
+    super(id, content.getLength())
    /**
     * The item that was originally to the left of this item.
     * @type {ID | null}
@@ -86,12 +247,12 @@ export class AbstractItem extends AbstractStruct {
    this.origin = origin
    /**
     * The item that is currently to the left of this item.
-     * @type {AbstractItem | null}
+     * @type {Item | null}
     */
    this.left = left
    /**
     * The item that is currently to the right of this item.
-     * @type {AbstractItem | null}
+     * @type {Item | null}
     */
    this.right = right
    /**
@@ -123,9 +284,19 @@ export class AbstractItem extends AbstractStruct {
    /**
     * If this type's effect is reundone this type refers to the type that undid
     * this operation.
-     * @type {AbstractItem | null}
+     * @type {ID | null}
     */
    this.redone = null
+    /**
+     * @type {AbstractContent}
+     */
+    this.content = content
+    this.length = content.getLength()
+    this.countable = content.isCountable()
+    /**
+     * If true, do not garbage collect this Item.
+     */
+    this.keep = false
  }

  /**
@@ -133,13 +304,13 @@ export class AbstractItem extends AbstractStruct {
   * @private
   */
  integrate (transaction) {
-    const store = transaction.y.store
+    const store = transaction.doc.store
    const id = this.id
    const parent = this.parent
    const parentSub = this.parentSub
    const length = this.length
    /**
-     * @type {AbstractItem|null}
+     * @type {Item|null}
     */
    let o
    // set o to the first conflicting item
@@ -155,11 +326,11 @@ export class AbstractItem extends AbstractStruct {
    }
    // TODO: use something like DeleteSet here (a tree implementation would be best)
    /**
-     * @type {Set<AbstractItem>}
+     * @type {Set<Item>}
     */
    const conflictingItems = new Set()
    /**
-     * @type {Set<AbstractItem>}
+     * @type {Set<Item>}
     */
    const itemsBeforeOrigin = new Set()
    // Let c in conflictingItems, b in itemsBeforeOrigin
@@ -218,8 +389,9 @@ export class AbstractItem extends AbstractStruct {
      parent._length += length
    }
    addStruct(store, this)
-    maplib.setIfUndefined(transaction.changed, parent, set.create).add(parentSub)
-    // @ts-ignore
+    this.content.integrate(transaction, this)
+    // add parent to transaction.changed
+    addChangedTypeToTransaction(transaction, parent, parentSub)
    if ((parent._item !== null && parent._item.deleted) || (this.right !== null && parentSub !== null)) {
      // delete if parent is deleted or if this is not the current attribute value of parent
      this.delete(transaction)
@@ -250,148 +422,44 @@ export class AbstractItem extends AbstractStruct {
    return n
  }

-  /**
-   * Creates an Item with the same effect as this Item (without position effect)
-   *
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   * @return {AbstractItem}
-   *
-   * @private
-   */
-  copy (id, left, origin, right, rightOrigin, parent, parentSub) {
-    throw new Error('unimplemented')
-  }
-
-  /**
-   * Redoes the effect of this operation.
-   *
-   * @param {Transaction} transaction The Yjs instance.
-   * @param {Set<AbstractItem>} redoitems
-   *
-   * @private
-   */
-  redo (transaction, redoitems) {
-    if (this.redone !== null) {
-      return this.redone
-    }
-    /**
-     * @type {any}
-     */
-    let parent = this.parent
-    if (parent === null) {
-      return
-    }
-    let left, right
-    if (this.parentSub === null) {
-      // Is an array item. Insert at the old position
-      left = this.left
-      right = this
-    } else {
-      // Is a map item. Insert as current value
-      left = parent.type._map.get(this.parentSub)
-      right = null
-    }
-    // make sure that parent is redone
-    if (parent._deleted === true && parent.redone === null) {
-      // try to undo parent if it will be undone anyway
-      if (!redoitems.has(parent) || !parent.redo(transaction, redoitems)) {
-        return false
-      }
-    }
-    if (parent.redone !== null) {
-      while (parent.redone !== null) {
-        parent = parent.redone
-      }
-      // find next cloned_redo items
-      while (left !== null) {
-        if (left.redone !== null && left.redone.parent === parent) {
-          left = left.redone
-          break
-        }
-        left = left.left
-      }
-      while (right !== null) {
-        if (right.redone !== null && right.redone.parent === parent) {
-          right = right.redone
-        }
-        right = right.right
-      }
-    }
-    this.redone = this.copy(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, this.parentSub)
-    this.redone.integrate(transaction)
-    return true
-  }
-
  /**
   * Computes the last content address of this Item.
   */
  get lastId () {
    return createID(this.id.client, this.id.clock + this.length - 1)
  }
-
  /**
-   * Computes the length of this Item.
-   */
-  get length () {
-    return 1
-  }
-
-  /**
-   * Should return false if this Item is some kind of meta information
-   * (e.g. format information).
+   * Try to merge two items
   *
-   * * Whether this Item should be addressable via `yarray.get(i)`
-   * * Whether this Item should be counted when computing yarray.length
-   */
-  get countable () {
-    return true
-  }
-
-  /**
-   * Do not call directly. Always split via StructStore!
-   *
-   * Splits this Item so that another Item can be inserted in-between.
-   * This must be overwritten if _length > 1
-   * Returns right part after split
-   *
-   * (see {@link ItemJSON}/{@link ItemString} for implementation)
-   *
-   * Does not integrate the struct, nor store it in struct store.
-   *
-   * This method should only be cally by StructStore.
-   *
-   * @param {Transaction} transaction
-   * @param {number} diff
-   * @return {AbstractItem}
-   *
-   * @private
-   */
-  splitAt (transaction, diff) {
-    throw new Error('unimplemented')
-  }
-
-  /**
-   * @param {AbstractItem} right
+   * @param {Item} right
   * @return {boolean}
-   *
-   * @private
   */
  mergeWith (right) {
-    if (compareIDs(right.origin, this.lastId) && this.right === right && compareIDs(this.rightOrigin, right.rightOrigin)) {
+    if (
+      compareIDs(right.origin, this.lastId) &&
+      this.right === right &&
+      compareIDs(this.rightOrigin, right.rightOrigin) &&
+      this.id.client === right.id.client &&
+      this.id.clock + this.length === right.id.clock &&
+      this.deleted === right.deleted &&
+      this.redone === null &&
+      right.redone === null &&
+      this.content.constructor === right.content.constructor &&
+      this.content.mergeWith(right.content)
+    ) {
+      if (right.keep) {
+        this.keep = true
+      }
      this.right = right.right
      if (this.right !== null) {
        this.right.left = this
      }
+      this.length += right.length
      return true
    }
    return false
  }
+
  /**
   * Mark this Item as deleted.
   *
@@ -407,49 +475,26 @@ export class AbstractItem extends AbstractStruct {
      this.deleted = true
      addToDeleteSet(transaction.deleteSet, this.id, this.length)
      maplib.setIfUndefined(transaction.changed, parent, set.create).add(this.parentSub)
+      this.content.delete(transaction)
    }
  }

  /**
-   * @param {Transaction} transaction
   * @param {StructStore} store
+   * @param {boolean} parentGCd
   *
   * @private
   */
-  gcChildren (transaction, store) { }
-
-  /**
-   * @param {Transaction} transaction
-   * @param {StructStore} store
-   *
-   * @private
-   */
-  gc (transaction, store) {
-    let r
-    if (this.parent._item !== null && this.parent._item.deleted) {
-      r = new GC(this.id, this.length)
+  gc (store, parentGCd) {
+    if (!this.deleted) {
+      throw error.unexpectedCase()
+    }
+    this.content.gc(store)
+    if (parentGCd) {
+      replaceStruct(store, this, new GC(this.id, this.length))
    } else {
-      r = new ItemDeleted(this.id, this.left, this.origin, this.right, this.rightOrigin, this.parent, this.parentSub, this.length)
-      if (r.right !== null) {
-        r.right.left = r
-      } else if (r.parentSub !== null) {
-        r.parent._map.set(r.parentSub, r)
-      }
-      if (r.left !== null) {
-        r.left.right = r
-      } else if (r.parentSub === null) {
-        r.parent._start = r
-      }
+      this.content = new ContentDeleted(this.length)
    }
-    replaceStruct(store, this, r)
-    transaction._mergeStructs.add(r.id)
-  }
-
-  /**
-   * @return {Array<any>}
-   */
-  getContent () {
-    throw error.methodUnimplemented()
  }

  /**
@@ -460,15 +505,14 @@ export class AbstractItem extends AbstractStruct {
   *
   * @param {encoding.Encoder} encoder The encoder to write data to.
   * @param {number} offset
-   * @param {number} encodingRef
   *
   * @private
   */
-  write (encoder, offset, encodingRef) {
+  write (encoder, offset) {
    const origin = offset > 0 ? createID(this.id.client, this.id.clock + offset - 1) : this.origin
    const rightOrigin = this.rightOrigin
    const parentSub = this.parentSub
-    const info = (encodingRef & binary.BITS5) |
+    const info = (this.content.getRef() & binary.BITS5) |
      (origin === null ? 0 : binary.BIT8) | // origin is defined
      (rightOrigin === null ? 0 : binary.BIT7) | // right origin is defined
      (parentSub === null ? 0 : binary.BIT6) // parentSub is non-null
@@ -484,26 +528,130 @@ export class AbstractItem extends AbstractStruct {
      if (parent._item === null) {
        // parent type on y._map
        // find the correct key
-        // @ts-ignore we know that y exists
        const ykey = findRootTypeKey(parent)
        encoding.writeVarUint(encoder, 1) // write parentYKey
        encoding.writeVarString(encoder, ykey)
      } else {
        encoding.writeVarUint(encoder, 0) // write parent id
-        // @ts-ignore _item is defined because parent is integrated
        writeID(encoder, parent._item.id)
      }
      if (parentSub !== null) {
        encoding.writeVarString(encoder, parentSub)
      }
    }
+    this.content.write(encoder, offset)
+  }
+}
+
+/**
+ * @param {decoding.Decoder} decoder
+ * @param {number} info
+ */
+const readItemContent = (decoder, info) => contentRefs[info & binary.BITS5](decoder)
+
+/**
+ * A lookup map for reading Item content.
+ *
+ * @type {Array<function(decoding.Decoder):AbstractContent>}
+ */
+export const contentRefs = [
+  () => { throw error.unexpectedCase() }, // GC is not ItemContent
+  readContentDeleted,
+  readContentJSON,
+  readContentBinary,
+  readContentString,
+  readContentEmbed,
+  readContentFormat,
+  readContentType,
+  readContentAny
+]
+
+/**
+ * Do not implement this class!
+ */
+export class AbstractContent {
+  /**
+   * @return {number}
+   */
+  getLength () {
+    throw error.methodUnimplemented()
+  }
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    throw error.methodUnimplemented()
+  }
+  /**
+   * Should return false if this Item is some kind of meta information
+   * (e.g. format information).
+   *
+   * * Whether this Item should be addressable via `yarray.get(i)`
+   * * Whether this Item should be counted when computing yarray.length
+   *
+   * @return {boolean}
+   */
+  isCountable () {
+    throw error.methodUnimplemented()
+  }
+  /**
+   * @return {AbstractContent}
+   */
+  copy () {
+    throw error.methodUnimplemented()
+  }
+  /**
+   * @param {number} offset
+   * @return {AbstractContent}
+   */
+  splice (offset) {
+    throw error.methodUnimplemented()
+  }
+  /**
+   * @param {AbstractContent} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    throw error.methodUnimplemented()
+  }
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {
+    throw error.methodUnimplemented()
+  }
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {
+    throw error.methodUnimplemented()
+  }
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {
+    throw error.methodUnimplemented()
+  }
+  /**
+   * @param {encoding.Encoder} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    throw error.methodUnimplemented()
+  }
+  /**
+   * @return {number}
+   */
+  getRef () {
+    throw error.methodUnimplemented()
  }
 }

 /**
 * @private
 */
-export class AbstractItemRef extends AbstractStructRef {
+export class ItemRef extends AbstractStructRef {
  /**
   * @param {decoding.Decoder} decoder
   * @param {ID} id
@@ -553,79 +701,70 @@ export class AbstractItemRef extends AbstractStructRef {
    if (this.parent !== null) {
      missing.push(this.parent)
    }
+    /**
+     * @type {AbstractContent}
+     */
+    this.content = readItemContent(decoder, info)
+    this.length = this.content.getLength()
  }
-}
-
-/**
- * @param {AbstractItemRef} item
- * @param {number} offset
- *
- * @function
- * @private
- */
-export const changeItemRefOffset = (item, offset) => {
-  item.id = createID(item.id.client, item.id.clock + offset)
-  item.left = createID(item.id.client, item.id.clock - 1)
-}
-
-export class ItemParams {
  /**
-   * @param {AbstractItem?} left
-   * @param {AbstractItem?} right
-   * @param {AbstractType<YEvent>?} parent
-   * @param {string|null} parentSub
+   * @param {Transaction} transaction
+   * @param {StructStore} store
+   * @param {number} offset
+   * @return {Item|GC}
   */
-  constructor (left, right, parent, parentSub) {
-    this.left = left
-    this.right = right
-    this.parent = parent
-    this.parentSub = parentSub
-  }
-}
+  toStruct (transaction, store, offset) {
+    if (offset > 0) {
+      /**
+       * @type {ID}
+       */
+      const id = this.id
+      this.id = createID(id.client, id.clock + offset)
+      this.left = createID(this.id.client, this.id.clock - 1)
+      this.content = this.content.splice(offset)
+      this.length -= offset
+    }

-/**
- * Outsourcing some of the logic of computing the item params from a received struct.
- * If parent === null, it is expected to gc the read struct. Otherwise apply it.
- *
- * @param {Transaction} transaction
- * @param {StructStore} store
- * @param {ID|null} leftid
- * @param {ID|null} rightid
- * @param {ID|null} parentid
- * @param {string|null} parentSub
- * @param {string|null} parentYKey
- * @return {ItemParams}
- *
- * @private
- * @function
- */
-export const computeItemParams = (transaction, store, leftid, rightid, parentid, parentSub, parentYKey) => {
-  const left = leftid === null ? null : getItemCleanEnd(transaction, store, leftid)
-  const right = rightid === null ? null : getItemCleanStart(transaction, store, rightid)
-  let parent = null
-  if (parentid !== null) {
-    const parentItem = getItemType(store, parentid)
-    switch (parentItem.constructor) {
-      case ItemDeleted:
-      case GC:
-        break
-      default:
-        parent = parentItem.type
+    const left = this.left === null ? null : getItemCleanEnd(transaction, store, this.left)
+    const right = this.right === null ? null : getItemCleanStart(transaction, store, this.right)
+    let parent = null
+    let parentSub = this.parentSub
+    if (this.parent !== null) {
+      const parentItem = getItem(store, this.parent)
+      // Edge case: toStruct is called with an offset > 0. In this case left is defined.
+      // Depending in which order structs arrive, left may be GC'd and the parent not
+      // deleted. This is why we check if left is GC'd. Strictly we don't have
+      // to check if right is GC'd, but we will in case we run into future issues
+      if (!parentItem.deleted && (left === null || left.constructor !== GC) && (right === null || right.constructor !== GC)) {
+        parent = /** @type {ContentType} */ (parentItem.content).type
+      }
+    } else if (this.parentYKey !== null) {
+      parent = transaction.doc.get(this.parentYKey)
+    } else if (left !== null) {
+      if (left.constructor !== GC) {
+        parent = left.parent
+        parentSub = left.parentSub
+      }
+    } else if (right !== null) {
+      if (right.constructor !== GC) {
+        parent = right.parent
+        parentSub = right.parentSub
+      }
+    } else {
+      throw error.unexpectedCase()
    }
-  } else if (parentYKey !== null) {
-    parent = transaction.y.get(parentYKey)
-  } else if (left !== null) {
-    if (left.constructor !== GC) {
-      parent = left.parent
-      parentSub = left.parentSub
-    }
-  } else if (right !== null) {
-    if (right.constructor !== GC) {
-      parent = right.parent
-      parentSub = right.parentSub
-    }
-  } else {
-    throw error.unexpectedCase()
+
+    return parent === null
+      ? new GC(this.id, this.length)
+      : new Item(
+        this.id,
+        left,
+        this.left,
+        right,
+        this.right,
+        parent,
+        parentSub,
+        this.content
+      )
  }
-  return new ItemParams(left, right, parent, parentSub)
 }
--- a/src/structs/ItemBinary.js
+++ b/src/structs/ItemBinary.js
@@ -1,98 +0,0 @@
-
-import {
-  AbstractItem,
-  AbstractItemRef,
-  computeItemParams,
-  GC,
-  StructStore, Transaction, AbstractType, ID // eslint-disable-line
-} from '../internals.js'
-
-import * as encoding from 'lib0/encoding.js'
-import * as decoding from 'lib0/decoding.js'
-
-/**
- * @private
- */
-export const structBinaryRefNumber = 1
-
-/**
- * @private
- */
-export class ItemBinary extends AbstractItem {
-  /**
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   * @param {ArrayBuffer} content
-   */
-  constructor (id, left, origin, right, rightOrigin, parent, parentSub, content) {
-    super(id, left, origin, right, rightOrigin, parent, parentSub)
-    this.content = content
-  }
-  getContent () {
-    return [this.content]
-  }
-  /**
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   */
-  copy (id, left, origin, right, rightOrigin, parent, parentSub) {
-    return new ItemBinary(id, left, origin, right, rightOrigin, parent, parentSub, this.content)
-  }
-  /**
-   * @param {encoding.Encoder} encoder
-   * @param {number} offset
-   */
-  write (encoder, offset) {
-    super.write(encoder, offset, structBinaryRefNumber)
-    encoding.writePayload(encoder, this.content)
-  }
-}
-
-/**
- * @private
- */
-export class ItemBinaryRef extends AbstractItemRef {
-  /**
-   * @param {decoding.Decoder} decoder
-   * @param {ID} id
-   * @param {number} info
-   */
-  constructor (decoder, id, info) {
-    super(decoder, id, info)
-    /**
-     * @type {ArrayBuffer}
-     */
-    this.content = decoding.readPayload(decoder)
-  }
-  /**
-   * @param {Transaction} transaction
-   * @param {StructStore} store
-   * @param {number} offset
-   * @return {ItemBinary|GC}
-   */
-  toStruct (transaction, store, offset) {
-    const { left, right, parent, parentSub } = computeItemParams(transaction, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
-    return parent === null
-      ? new GC(this.id, this.length)
-      : new ItemBinary(
-        this.id,
-        left,
-        this.left,
-        right,
-        this.right,
-        parent,
-        parentSub,
-        this.content
-      )
-  }
-}
--- a/src/structs/ItemDeleted.js
+++ b/src/structs/ItemDeleted.js
@@ -1,142 +0,0 @@
-
-import {
-  AbstractItem,
-  AbstractItemRef,
-  computeItemParams,
-  changeItemRefOffset,
-  GC,
-  splitItem,
-  addToDeleteSet,
-  Y, StructStore, Transaction, ID, AbstractType // eslint-disable-line
-} from '../internals.js'
-
-import * as encoding from 'lib0/encoding.js'
-import * as decoding from 'lib0/decoding.js'
-
-/**
- * @private
- */
-export const structDeletedRefNumber = 2
-
-/**
- * @private
- */
-export class ItemDeleted extends AbstractItem {
-  /**
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   * @param {number} length
-   */
-  constructor (id, left, origin, right, rightOrigin, parent, parentSub, length) {
-    super(id, left, origin, right, rightOrigin, parent, parentSub)
-    this._len = length
-    this.deleted = true
-  }
-  get length () {
-    return this._len
-  }
-  /**
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   */
-  copy (id, left, origin, right, rightOrigin, parent, parentSub) {
-    return new ItemDeleted(id, left, origin, right, rightOrigin, parent, parentSub, this.length)
-  }
-  /**
-   * @param {Transaction} transaction
-   */
-  integrate (transaction) {
-    super.integrate(transaction)
-    addToDeleteSet(transaction.deleteSet, this.id, this.length)
-  }
-  /**
-   * @param {Transaction} transaction
-   * @param {number} diff
-   */
-  splitAt (transaction, diff) {
-    /**
-     * @type {ItemDeleted}
-     */
-    // @ts-ignore
-    const right = splitItem(transaction, this, diff)
-    right._len -= diff
-    this._len = diff
-    return right
-  }
-  /**
-   * @param {ItemDeleted} right
-   * @return {boolean}
-   */
-  mergeWith (right) {
-    if (super.mergeWith(right)) {
-      this._len += right._len
-      return true
-    }
-    return false
-  }
-  /**
-   * @param {encoding.Encoder} encoder
-   * @param {number} offset
-   */
-  write (encoder, offset) {
-    super.write(encoder, offset, structDeletedRefNumber)
-    encoding.writeVarUint(encoder, this.length - offset)
-  }
-}
-
-/**
- * @private
- */
-export class ItemDeletedRef extends AbstractItemRef {
-  /**
-   * @param {decoding.Decoder} decoder
-   * @param {ID} id
-   * @param {number} info
-   */
-  constructor (decoder, id, info) {
-    super(decoder, id, info)
-    /**
-     * @type {number}
-     */
-    this.len = decoding.readVarUint(decoder)
-  }
-  get length () {
-    return this.len
-  }
-  /**
-   * @param {Transaction} transaction
-   * @param {StructStore} store
-   * @param {number} offset
-   * @return {ItemDeleted|GC}
-   */
-  toStruct (transaction, store, offset) {
-    if (offset > 0) {
-      changeItemRefOffset(this, offset)
-      this.len = this.len - offset
-    }
-
-    const { left, right, parent, parentSub } = computeItemParams(transaction, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
-    return parent === null
-      ? new GC(this.id, this.length)
-      : new ItemDeleted(
-        this.id,
-        left,
-        this.left,
-        right,
-        this.right,
-        parent,
-        parentSub,
-        this.len
-      )
-  }
-}
--- a/src/structs/ItemEmbed.js
+++ b/src/structs/ItemEmbed.js
@@ -1,95 +0,0 @@
-
-import {
-  AbstractItem,
-  AbstractItemRef,
-  computeItemParams,
-  GC,
-  Transaction, StructStore, ID, AbstractType // eslint-disable-line
-} from '../internals.js'
-
-import * as encoding from 'lib0/encoding.js'
-import * as decoding from 'lib0/decoding.js'
-
-/**
- * @private
- */
-export const structEmbedRefNumber = 3
-
-/**
- * @private
- */
-export class ItemEmbed extends AbstractItem {
-  /**
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   * @param {Object} embed
-   */
-  constructor (id, left, origin, right, rightOrigin, parent, parentSub, embed) {
-    super(id, left, origin, right, rightOrigin, parent, parentSub)
-    this.embed = embed
-  }
-  /**
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   */
-  copy (id, left, origin, right, rightOrigin, parent, parentSub) {
-    return new ItemEmbed(id, left, origin, right, rightOrigin, parent, parentSub, this.embed)
-  }
-  /**
-   * @param {encoding.Encoder} encoder
-   * @param {number} offset
-   */
-  write (encoder, offset) {
-    super.write(encoder, offset, structEmbedRefNumber)
-    encoding.writeVarString(encoder, JSON.stringify(this.embed))
-  }
-}
-
-/**
- * @private
- */
-export class ItemEmbedRef extends AbstractItemRef {
-  /**
-   * @param {decoding.Decoder} decoder
-   * @param {ID} id
-   * @param {number} info
-   */
-  constructor (decoder, id, info) {
-    super(decoder, id, info)
-    /**
-     * @type {ArrayBuffer}
-     */
-    this.embed = JSON.parse(decoding.readVarString(decoder))
-  }
-  /**
-   * @param {Transaction} transaction
-   * @param {StructStore} store
-   * @param {number} offset
-   * @return {ItemEmbed|GC}
-   */
-  toStruct (transaction, store, offset) {
-    const { left, right, parent, parentSub } = computeItemParams(transaction, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
-    return parent === null
-      ? new GC(this.id, this.length)
-      : new ItemEmbed(
-        this.id,
-        left,
-        this.left,
-        right,
-        this.right,
-        parent,
-        parentSub,
-        this.embed
-      )
-  }
-}
--- a/src/structs/ItemFormat.js
+++ b/src/structs/ItemFormat.js
@@ -1,103 +0,0 @@
-
-import {
-  AbstractItem,
-  AbstractItemRef,
-  computeItemParams,
-  GC,
-  Transaction, StructStore, ID, AbstractType // eslint-disable-line
-} from '../internals.js'
-
-import * as encoding from 'lib0/encoding.js'
-import * as decoding from 'lib0/decoding.js'
-
-/**
- * @private
- */
-export const structFormatRefNumber = 4
-
-/**
- * @private
- */
-export class ItemFormat extends AbstractItem {
-  /**
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   * @param {string} key
-   * @param {any} value
-   */
-  constructor (id, left, origin, right, rightOrigin, parent, parentSub, key, value) {
-    super(id, left, origin, right, rightOrigin, parent, parentSub)
-    this.key = key
-    this.value = value
-  }
-  /**
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   */
-  copy (id, left, origin, right, rightOrigin, parent, parentSub) {
-    return new ItemFormat(id, left, origin, right, rightOrigin, parent, parentSub, this.key, this.value)
-  }
-  get countable () {
-    return false
-  }
-  /**
-   * @param {encoding.Encoder} encoder
-   * @param {number} offset
-   */
-  write (encoder, offset) {
-    super.write(encoder, offset, structFormatRefNumber)
-    encoding.writeVarString(encoder, this.key)
-    encoding.writeVarString(encoder, JSON.stringify(this.value))
-  }
-}
-
-/**
- * @private
- */
-export class ItemFormatRef extends AbstractItemRef {
-  /**
-   * @param {decoding.Decoder} decoder
-   * @param {ID} id
-   * @param {number} info
-   */
-  constructor (decoder, id, info) {
-    super(decoder, id, info)
-    /**
-     * @type {string}
-     */
-    this.key = decoding.readVarString(decoder)
-    this.value = JSON.parse(decoding.readVarString(decoder))
-  }
-  /**
-   * @param {Transaction} transaction
-   * @param {StructStore} store
-   * @param {number} offset
-   * @return {ItemFormat|GC}
-   */
-  toStruct (transaction, store, offset) {
-    const { left, right, parent, parentSub } = computeItemParams(transaction, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
-    return parent === null
-      ? new GC(this.id, this.length)
-      : new ItemFormat(
-        this.id,
-        left,
-        this.left,
-        right,
-        this.right,
-        parent,
-        parentSub,
-        this.key,
-        this.value
-      )
-  }
-}
--- a/src/structs/ItemJSON.js
+++ b/src/structs/ItemJSON.js
@@ -1,152 +0,0 @@
-
-import {
-  AbstractItem,
-  AbstractItemRef,
-  computeItemParams,
-  splitItem,
-  changeItemRefOffset,
-  GC,
-  Transaction, StructStore, Y, ID, AbstractType // eslint-disable-line
-} from '../internals.js'
-
-import * as encoding from 'lib0/encoding.js'
-import * as decoding from 'lib0/decoding.js'
-
-/**
- * @private
- */
-export const structJSONRefNumber = 5
-
-/**
- * @private
- */
-export class ItemJSON extends AbstractItem {
-  /**
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   * @param {Array<any>} content
-   */
-  constructor (id, left, origin, right, rightOrigin, parent, parentSub, content) {
-    super(id, left, origin, right, rightOrigin, parent, parentSub)
-    /**
-     * @type {Array<any>}
-     */
-    this.content = content
-  }
-  /**
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   */
-  copy (id, left, origin, right, rightOrigin, parent, parentSub) {
-    return new ItemJSON(id, left, origin, right, rightOrigin, parent, parentSub, this.content)
-  }
-  get length () {
-    return this.content.length
-  }
-  getContent () {
-    return this.content
-  }
-  /**
-   * @param {Transaction} transaction
-   * @param {number} diff
-   */
-  splitAt (transaction, diff) {
-    /**
-     * @type {ItemJSON}
-     */
-    // @ts-ignore
-    const right = splitItem(transaction, this, diff)
-    right.content = this.content.splice(diff)
-    return right
-  }
-  /**
-   * @param {ItemJSON} right
-   * @return {boolean}
-   */
-  mergeWith (right) {
-    if (super.mergeWith(right)) {
-      this.content = this.content.concat(right.content)
-      return true
-    }
-    return false
-  }
-  /**
-   * @param {encoding.Encoder} encoder
-   * @param {number} offset
-   */
-  write (encoder, offset) {
-    super.write(encoder, offset, structJSONRefNumber)
-    const len = this.content.length
-    encoding.writeVarUint(encoder, len - offset)
-    for (let i = offset; i < len; i++) {
-      const c = this.content[i]
-      encoding.writeVarString(encoder, c === undefined ? 'undefined' : JSON.stringify(c))
-    }
-  }
-}
-
-/**
- * @private
- */
-export class ItemJSONRef extends AbstractItemRef {
-  /**
-   * @param {decoding.Decoder} decoder
-   * @param {ID} id
-   * @param {number} info
-   */
-  constructor (decoder, id, info) {
-    super(decoder, id, info)
-    const len = decoding.readVarUint(decoder)
-    const cs = []
-    for (let i = 0; i < len; i++) {
-      const c = decoding.readVarString(decoder)
-      if (c === 'undefined') {
-        cs.push(undefined)
-      } else {
-        cs.push(JSON.parse(c))
-      }
-    }
-    /**
-     * @type {Array<any>}
-     */
-    this.content = cs
-  }
-  get length () {
-    return this.content.length
-  }
-  /**
-   * @param {Transaction} transaction
-   * @param {StructStore} store
-   * @param {number} offset
-   * @return {ItemJSON|GC}
-   */
-  toStruct (transaction, store, offset) {
-    if (offset > 0) {
-      changeItemRefOffset(this, offset)
-      this.content = this.content.slice(offset)
-    }
-    const { left, right, parent, parentSub } = computeItemParams(transaction, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
-    return parent === null
-      ? new GC(this.id, this.length)
-      : new ItemJSON(
-        this.id,
-        left,
-        this.left,
-        right,
-        this.right,
-        parent,
-        parentSub,
-        this.content
-      )
-  }
-}
--- a/src/structs/ItemString.js
+++ b/src/structs/ItemString.js
@@ -1,137 +0,0 @@
-
-import {
-  AbstractItem,
-  AbstractItemRef,
-  computeItemParams,
-  splitItem,
-  changeItemRefOffset,
-  GC,
-  Transaction, StructStore, Y, ID, AbstractType // eslint-disable-line
-} from '../internals.js'
-
-import * as encoding from 'lib0/encoding.js'
-import * as decoding from 'lib0/decoding.js'
-
-export const structStringRefNumber = 6
-
-/**
- * @private
- */
-export class ItemString extends AbstractItem {
-  /**
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   * @param {string} string
-   */
-  constructor (id, left, origin, right, rightOrigin, parent, parentSub, string) {
-    super(id, left, origin, right, rightOrigin, parent, parentSub)
-    /**
-     * @type {string}
-     */
-    this.string = string
-  }
-  /**
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   */
-  copy (id, left, origin, right, rightOrigin, parent, parentSub) {
-    return new ItemString(id, left, origin, right, rightOrigin, parent, parentSub, this.string)
-  }
-  getContent () {
-    return this.string.split('')
-  }
-  get length () {
-    return this.string.length
-  }
-  /**
-   * @param {Transaction} transaction
-   * @param {number} diff
-   * @return {ItemString}
-   */
-  splitAt (transaction, diff) {
-    /**
-     * @type {ItemString}
-     */
-    // @ts-ignore
-    const right = splitItem(transaction, this, diff)
-    right.string = this.string.slice(diff)
-    this.string = this.string.slice(0, diff)
-    return right
-  }
-  /**
-   * @param {ItemString} right
-   * @return {boolean}
-   */
-  mergeWith (right) {
-    if (super.mergeWith(right)) {
-      this.string += right.string
-      return true
-    }
-    return false
-  }
-  /**
-   * @param {encoding.Encoder} encoder
-   * @param {number} offset
-   */
-  write (encoder, offset) {
-    super.write(encoder, offset, structStringRefNumber)
-    encoding.writeVarString(encoder, offset === 0 ? this.string : this.string.slice(offset))
-  }
-}
-
-/**
- * @private
- */
-export class ItemStringRef extends AbstractItemRef {
-  /**
-   * @param {decoding.Decoder} decoder
-   * @param {ID} id
-   * @param {number} info
-   */
-  constructor (decoder, id, info) {
-    super(decoder, id, info)
-    /**
-     * @type {string}
-     */
-    this.string = decoding.readVarString(decoder)
-  }
-  get length () {
-    return this.string.length
-  }
-  /**
-   * @param {Transaction} transaction
-   * @param {StructStore} store
-   * @param {number} offset
-   * @return {ItemString|GC}
-   */
-  toStruct (transaction, store, offset) {
-    if (offset > 0) {
-      changeItemRefOffset(this, offset)
-      this.string = this.string.slice(offset)
-    }
-
-    const { left, right, parent, parentSub } = computeItemParams(transaction, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
-    return parent === null
-      ? new GC(this.id, this.length)
-      : new ItemString(
-        this.id,
-        left,
-        this.left,
-        right,
-        this.right,
-        parent,
-        parentSub,
-        this.string
-      )
-  }
-}
--- a/src/structs/ItemType.js
+++ b/src/structs/ItemType.js
@@ -1,178 +0,0 @@
-
-import {
-  AbstractItem,
-  AbstractItemRef,
-  computeItemParams,
-  readYArray,
-  readYMap,
-  readYText,
-  readYXmlElement,
-  readYXmlFragment,
-  readYXmlHook,
-  readYXmlText,
-  StructStore, Y, GC, Transaction, ID, AbstractType // eslint-disable-line
-} from '../internals.js'
-
-import * as encoding from 'lib0/encoding.js' // eslint-disable-line
-import * as decoding from 'lib0/decoding.js'
-
-/**
- * @private
- */
-export const structTypeRefNumber = 7
-
-/**
- * @type {Array<function(decoding.Decoder):AbstractType<any>>}
- * @private
- */
-export const typeRefs = [
-  readYArray,
-  readYMap,
-  readYText,
-  readYXmlElement,
-  readYXmlFragment,
-  readYXmlHook,
-  readYXmlText
-]
-
-export const YArrayRefID = 0
-export const YMapRefID = 1
-export const YTextRefID = 2
-export const YXmlElementRefID = 3
-export const YXmlFragmentRefID = 4
-export const YXmlHookRefID = 5
-export const YXmlTextRefID = 6
-
-/**
- * @private
- */
-export class ItemType extends AbstractItem {
-  /**
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   * @param {AbstractType<any>} type
-   */
-  constructor (id, left, origin, right, rightOrigin, parent, parentSub, type) {
-    super(id, left, origin, right, rightOrigin, parent, parentSub)
-    this.type = type
-  }
-
-  getContent () {
-    return [this.type]
-  }
-  /**
-   * @param {ID} id
-   * @param {AbstractItem | null} left
-   * @param {ID | null} origin
-   * @param {AbstractItem | null} right
-   * @param {ID | null} rightOrigin
-   * @param {AbstractType<any>} parent
-   * @param {string | null} parentSub
-   * @return {ItemType}
-   */
-  copy (id, left, origin, right, rightOrigin, parent, parentSub) {
-    return new ItemType(id, left, origin, right, rightOrigin, parent, parentSub, this.type._copy())
-  }
-  /**
-   * @param {Transaction} transaction
-   */
-  integrate (transaction) {
-    super.integrate(transaction)
-    this.type._integrate(transaction.y, this)
-  }
-  /**
-   * @param {encoding.Encoder} encoder
-   * @param {number} offset
-   */
-  write (encoder, offset) {
-    super.write(encoder, offset, structTypeRefNumber)
-    this.type._write(encoder)
-  }
-  /**
-   * Mark this Item as deleted.
-   *
-   * @param {Transaction} transaction The Yjs instance
-   * @private
-   */
-  delete (transaction) {
-    super.delete(transaction)
-    transaction.changed.delete(this.type)
-    transaction.changedParentTypes.delete(this.type)
-    this.gcChildren(transaction, transaction.y.store)
-  }
-
-  /**
-   * @param {Transaction} transaction
-   * @param {StructStore} store
-   */
-  gcChildren (transaction, store) {
-    let item = this.type._start
-    while (item !== null) {
-      item.gc(transaction, store)
-      item = item.right
-    }
-    this.type._start = null
-    this.type._map.forEach(item => {
-      while (item !== null) {
-        item.gc(transaction, store)
-        // @ts-ignore
-        item = item.left
-      }
-    })
-    this._map = new Map()
-  }
-
-  /**
-   * @param {Transaction} transaction
-   * @param {StructStore} store
-   */
-  gc (transaction, store) {
-    super.gc(transaction, store)
-    this.gcChildren(transaction, store)
-  }
-}
-
-/**
- * @private
- */
-export class ItemTypeRef extends AbstractItemRef {
-  /**
-   * @param {decoding.Decoder} decoder
-   * @param {ID} id
-   * @param {number} info
-   */
-  constructor (decoder, id, info) {
-    super(decoder, id, info)
-    const typeRef = decoding.readVarUint(decoder)
-    /**
-     * @type {AbstractType<any>}
-     */
-    this.type = typeRefs[typeRef](decoder)
-  }
-  /**
-   * @param {Transaction} transaction
-   * @param {StructStore} store
-   * @param {number} offset
-   * @return {ItemType|GC}
-   */
-  toStruct (transaction, store, offset) {
-    const { left, right, parent, parentSub } = computeItemParams(transaction, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
-    return parent === null
-      ? new GC(this.id, this.length)
-      : new ItemType(
-        this.id,
-        left,
-        this.left,
-        right,
-        this.right,
-        parent,
-        parentSub,
-        this.type
-      )
-  }
-}
--- a/src/types/AbstractType.js
+++ b/src/types/AbstractType.js
@@ -4,14 +4,14 @@ import {
  callEventHandlerListeners,
  addEventHandlerListener,
  createEventHandler,
-  ItemType,
  nextID,
  isVisible,
-  ItemJSON,
-  ItemBinary,
+  ContentType,
+  ContentAny,
+  ContentBinary,
  createID,
  getItemCleanStart,
-  Y, Snapshot, Transaction, EventHandler, YEvent, AbstractItem, // eslint-disable-line
+  Doc, Snapshot, Transaction, EventHandler, YEvent, Item, // eslint-disable-line
 } from '../internals.js'

 import * as map from 'lib0/map.js'
@@ -49,24 +49,24 @@ export const callTypeObservers = (type, transaction, event) => {
 export class AbstractType {
  constructor () {
    /**
-     * @type {ItemType|null}
+     * @type {Item|null}
     */
    this._item = null
    /**
     * @private
-     * @type {Map<string,AbstractItem>}
+     * @type {Map<string,Item>}
     */
    this._map = new Map()
    /**
     * @private
-     * @type {AbstractItem|null}
+     * @type {Item|null}
     */
    this._start = null
    /**
     * @private
-     * @type {Y|null}
+     * @type {Doc|null}
     */
-    this._y = null
+    this.doc = null
    this._length = 0
    /**
     * Event handlers
@@ -87,12 +87,12 @@ export class AbstractType {
   * * This type is sent to other client
   * * Observer functions are fired
   *
-   * @param {Y} y The Yjs instance
-   * @param {ItemType|null} item
+   * @param {Doc} y The Yjs instance
+   * @param {Item|null} item
   * @private
   */
  _integrate (y, item) {
-    this._y = y
+    this.doc = y
    this._item = item
  }

@@ -101,7 +101,7 @@ export class AbstractType {
   * @private
   */
  _copy () {
-    throw new Error('unimplemented')
+    throw error.methodUnimplemented()
  }

  /**
@@ -182,12 +182,35 @@ export class AbstractType {
 * @private
 * @function
 */
-export const typeArrayToArray = type => {
+export const typeListToArray = type => {
  const cs = []
  let n = type._start
  while (n !== null) {
    if (n.countable && !n.deleted) {
-      const c = n.getContent()
+      const c = n.content.getContent()
+      for (let i = 0; i < c.length; i++) {
+        cs.push(c[i])
+      }
+    }
+    n = n.right
+  }
+  return cs
+}
+
+/**
+ * @param {AbstractType<any>} type
+ * @param {Snapshot} snapshot
+ * @return {Array<any>}
+ *
+ * @private
+ * @function
+ */
+export const typeListToArraySnapshot = (type, snapshot) => {
+  const cs = []
+  let n = type._start
+  while (n !== null) {
+    if (n.countable && isVisible(n, snapshot)) {
+      const c = n.content.getContent()
      for (let i = 0; i < c.length; i++) {
        cs.push(c[i])
      }
@@ -201,17 +224,17 @@ export const typeArrayToArray = type => {
 * Executes a provided function on once on overy element of this YArray.
 *
 * @param {AbstractType<any>} type
- * @param {function(any,number,AbstractType<any>):void} f A function to execute on every element of this YArray.
+ * @param {function(any,number,any):void} f A function to execute on every element of this YArray.
 *
 * @private
 * @function
 */
-export const typeArrayForEach = (type, f) => {
+export const typeListForEach = (type, f) => {
  let index = 0
  let n = type._start
  while (n !== null) {
    if (n.countable && !n.deleted) {
-      const c = n.getContent()
+      const c = n.content.getContent()
      for (let i = 0; i < c.length; i++) {
        f(c[i], index++, type)
      }
@@ -229,12 +252,12 @@ export const typeArrayForEach = (type, f) => {
 * @private
 * @function
 */
-export const typeArrayMap = (type, f) => {
+export const typeListMap = (type, f) => {
  /**
   * @type {Array<any>}
   */
  const result = []
-  typeArrayForEach(type, (c, i) => {
+  typeListForEach(type, (c, i) => {
    result.push(f(c, i, type))
  })
  return result
@@ -247,7 +270,7 @@ export const typeArrayMap = (type, f) => {
 * @private
 * @function
 */
-export const typeArrayCreateIterator = type => {
+export const typeListCreateIterator = type => {
  let n = type._start
  /**
   * @type {Array<any>|null}
@@ -264,18 +287,15 @@ export const typeArrayCreateIterator = type => {
        while (n !== null && n.deleted) {
          n = n.right
        }
-      }
-      // check if we reached the end, no need to check currentContent, because it does not exist
-      if (n === null) {
-        return {
-          done: true,
-          value: undefined
+        // check if we reached the end, no need to check currentContent, because it does not exist
+        if (n === null) {
+          return {
+            done: true,
+            value: undefined
+          }
        }
-      }
-      // currentContent could exist from the last iteration
-      if (currentContent === null) {
        // we found n, so we can set currentContent
-        currentContent = n.getContent()
+        currentContent = n.content.getContent()
        currentContentIndex = 0
        n = n.right // we used the content of n, now iterate to next
      }
@@ -303,12 +323,12 @@ export const typeArrayCreateIterator = type => {
 * @private
 * @function
 */
-export const typeArrayForEachSnapshot = (type, f, snapshot) => {
+export const typeListForEachSnapshot = (type, f, snapshot) => {
  let index = 0
  let n = type._start
  while (n !== null) {
    if (n.countable && isVisible(n, snapshot)) {
-      const c = n.getContent()
+      const c = n.content.getContent()
      for (let i = 0; i < c.length; i++) {
        f(c[i], index++, type)
      }
@@ -325,11 +345,11 @@ export const typeArrayForEachSnapshot = (type, f, snapshot) => {
 * @private
 * @function
 */
-export const typeArrayGet = (type, index) => {
+export const typeListGet = (type, index) => {
  for (let n = type._start; n !== null; n = n.right) {
    if (!n.deleted && n.countable) {
      if (index < n.length) {
-        return n.getContent()[index]
+        return n.content.getContent()[index]
      }
      index -= n.length
    }
@@ -339,13 +359,13 @@ export const typeArrayGet = (type, index) => {
 /**
 * @param {Transaction} transaction
 * @param {AbstractType<any>} parent
- * @param {AbstractItem?} referenceItem
- * @param {Array<Object<string,any>|Array<any>|number|string|ArrayBuffer>} content
+ * @param {Item?} referenceItem
+ * @param {Array<Object<string,any>|Array<any>|boolean|number|string|Uint8Array>} content
 *
 * @private
 * @function
 */
-export const typeArrayInsertGenericsAfter = (transaction, parent, referenceItem, content) => {
+export const typeListInsertGenericsAfter = (transaction, parent, referenceItem, content) => {
  let left = referenceItem
  const right = referenceItem === null ? parent._start : referenceItem.right
  /**
@@ -354,7 +374,7 @@ export const typeArrayInsertGenericsAfter = (transaction, parent, referenceItem,
  let jsonContent = []
  const packJsonContent = () => {
    if (jsonContent.length > 0) {
-      left = new ItemJSON(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, null, jsonContent)
+      left = new Item(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, null, new ContentAny(jsonContent))
      left.integrate(transaction)
      jsonContent = []
    }
@@ -363,6 +383,7 @@ export const typeArrayInsertGenericsAfter = (transaction, parent, referenceItem,
    switch (c.constructor) {
      case Number:
      case Object:
+      case Boolean:
      case Array:
      case String:
        jsonContent.push(c)
@@ -370,15 +391,14 @@ export const typeArrayInsertGenericsAfter = (transaction, parent, referenceItem,
      default:
        packJsonContent()
        switch (c.constructor) {
+          case Uint8Array:
          case ArrayBuffer:
-            // @ts-ignore c is definitely an ArrayBuffer
-            left = new ItemBinary(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, null, c)
-            // @ts-ignore
+            left = new Item(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, null, new ContentBinary(new Uint8Array(/** @type {Uint8Array} */ (c))))
            left.integrate(transaction)
            break
          default:
            if (c instanceof AbstractType) {
-              left = new ItemType(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, null, c)
+              left = new Item(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, null, new ContentType(c))
              left.integrate(transaction)
            } else {
              throw new Error('Unexpected content type in insert operation')
@@ -393,14 +413,14 @@ export const typeArrayInsertGenericsAfter = (transaction, parent, referenceItem,
 * @param {Transaction} transaction
 * @param {AbstractType<any>} parent
 * @param {number} index
- * @param {Array<Object<string,any>|Array<any>|number|string|ArrayBuffer>} content
+ * @param {Array<Object<string,any>|Array<any>|number|string|Uint8Array>} content
 *
 * @private
 * @function
 */
-export const typeArrayInsertGenerics = (transaction, parent, index, content) => {
+export const typeListInsertGenerics = (transaction, parent, index, content) => {
  if (index === 0) {
-    return typeArrayInsertGenericsAfter(transaction, parent, null, content)
+    return typeListInsertGenericsAfter(transaction, parent, null, content)
  }
  let n = parent._start
  for (; n !== null; n = n.right) {
@@ -408,14 +428,14 @@ export const typeArrayInsertGenerics = (transaction, parent, index, content) =>
      if (index <= n.length) {
        if (index < n.length) {
          // insert in-between
-          getItemCleanStart(transaction, transaction.y.store, createID(n.id.client, n.id.clock + index))
+          getItemCleanStart(transaction, transaction.doc.store, createID(n.id.client, n.id.clock + index))
        }
        break
      }
      index -= n.length
    }
  }
-  return typeArrayInsertGenericsAfter(transaction, parent, n, content)
+  return typeListInsertGenericsAfter(transaction, parent, n, content)
 }

 /**
@@ -427,17 +447,14 @@ export const typeArrayInsertGenerics = (transaction, parent, index, content) =>
 * @private
 * @function
 */
-export const typeArrayDelete = (transaction, parent, index, length) => {
+export const typeListDelete = (transaction, parent, index, length) => {
  if (length === 0) { return }
  let n = parent._start
  // compute the first item to be deleted
-  for (; n !== null; n = n.right) {
+  for (; n !== null && index > 0; n = n.right) {
    if (!n.deleted && n.countable) {
-      if (index <= n.length) {
-        if (index < n.length && index > 0) {
-          n = getItemCleanStart(transaction, transaction.y.store, createID(n.id.client, n.id.clock + index))
-        }
-        break
+      if (index < n.length) {
+        getItemCleanStart(transaction, transaction.doc.store, createID(n.id.client, n.id.clock + index))
      }
      index -= n.length
    }
@@ -446,7 +463,7 @@ export const typeArrayDelete = (transaction, parent, index, length) => {
  while (length > 0 && n !== null) {
    if (!n.deleted) {
      if (length < n.length) {
-        getItemCleanStart(transaction, transaction.y.store, createID(n.id.client, n.id.clock + length))
+        getItemCleanStart(transaction, transaction.doc.store, createID(n.id.client, n.id.clock + length))
      }
      n.delete(transaction)
      length -= n.length
@@ -477,52 +494,55 @@ export const typeMapDelete = (transaction, parent, key) => {
 * @param {Transaction} transaction
 * @param {AbstractType<any>} parent
 * @param {string} key
- * @param {Object|number|Array<any>|string|ArrayBuffer|AbstractType<any>} value
+ * @param {Object|number|Array<any>|string|Uint8Array|AbstractType<any>} value
 *
 * @private
 * @function
 */
 export const typeMapSet = (transaction, parent, key, value) => {
  const left = parent._map.get(key) || null
+  let content
  if (value == null) {
-    new ItemJSON(nextID(transaction), left, left === null ? null : left.lastId, null, null, parent, key, [value]).integrate(transaction)
-    return
-  }
-  switch (value.constructor) {
-    case Number:
-    case Object:
-    case Array:
-    case String:
-      new ItemJSON(nextID(transaction), left, left === null ? null : left.lastId, null, null, parent, key, [value]).integrate(transaction)
-      break
-    case ArrayBuffer:
-      new ItemBinary(nextID(transaction), left, left === null ? null : left.lastId, null, null, parent, key, value).integrate(transaction)
-      break
-    default:
-      if (value instanceof AbstractType) {
-        new ItemType(nextID(transaction), left, left === null ? null : left.lastId, null, null, parent, key, value).integrate(transaction)
-      } else {
-        throw new Error('Unexpected content type')
-      }
+    content = new ContentAny([value])
+  } else {
+    switch (value.constructor) {
+      case Number:
+      case Object:
+      case Boolean:
+      case Array:
+      case String:
+        content = new ContentAny([value])
+        break
+      case Uint8Array:
+        content = new ContentBinary(value)
+        break
+      default:
+        if (value instanceof AbstractType) {
+          content = new ContentType(value)
+        } else {
+          throw new Error('Unexpected content type')
+        }
+    }
  }
+  new Item(nextID(transaction), left, left === null ? null : left.lastId, null, null, parent, key, content).integrate(transaction)
 }

 /**
 * @param {AbstractType<any>} parent
 * @param {string} key
- * @return {Object<string,any>|number|Array<any>|string|ArrayBuffer|AbstractType<any>|undefined}
+ * @return {Object<string,any>|number|Array<any>|string|Uint8Array|AbstractType<any>|undefined}
 *
 * @private
 * @function
 */
 export const typeMapGet = (parent, key) => {
  const val = parent._map.get(key)
-  return val !== undefined && !val.deleted ? val.getContent()[0] : undefined
+  return val !== undefined && !val.deleted ? val.content.getContent()[val.length - 1] : undefined
 }

 /**
 * @param {AbstractType<any>} parent
- * @return {Object<string,Object<string,any>|number|Array<any>|string|ArrayBuffer|AbstractType<any>|undefined>}
+ * @return {Object<string,Object<string,any>|number|Array<any>|string|Uint8Array|AbstractType<any>|undefined>}
 *
 * @private
 * @function
@@ -534,7 +554,7 @@ export const typeMapGetAll = (parent) => {
  let res = {}
  for (const [key, value] of parent._map) {
    if (!value.deleted) {
-      res[key] = value.getContent()[value.length - 1]
+      res[key] = value.content.getContent()[value.length - 1]
    }
  }
  return res
@@ -557,7 +577,7 @@ export const typeMapHas = (parent, key) => {
 * @param {AbstractType<any>} parent
 * @param {string} key
 * @param {Snapshot} snapshot
- * @return {Object<string,any>|number|Array<any>|string|ArrayBuffer|AbstractType<any>|undefined}
+ * @return {Object<string,any>|number|Array<any>|string|Uint8Array|AbstractType<any>|undefined}
 *
 * @private
 * @function
@@ -567,14 +587,14 @@ export const typeMapGetSnapshot = (parent, key, snapshot) => {
  while (v !== null && (!snapshot.sm.has(v.id.client) || v.id.clock >= (snapshot.sm.get(v.id.client) || 0))) {
    v = v.left
  }
-  return v !== null && isVisible(v, snapshot) ? v.getContent()[v.length - 1] : undefined
+  return v !== null && isVisible(v, snapshot) ? v.content.getContent()[v.length - 1] : undefined
 }

 /**
- * @param {Map<string,AbstractItem>} map
+ * @param {Map<string,Item>} map
 * @return {IterableIterator<Array<any>>}
 *
 * @private
 * @function
 */
-export const createMapIterator = map => iterator.iteratorFilter(map.entries(), entry => !entry[1].deleted)
+export const createMapIterator = map => iterator.iteratorFilter(map.entries(), /** @param {any} entry */ entry => !entry[1].deleted)
--- a/src/types/YArray.js
+++ b/src/types/YArray.js
@@ -5,17 +5,17 @@
 import {
  YEvent,
  AbstractType,
-  typeArrayGet,
-  typeArrayToArray,
-  typeArrayForEach,
-  typeArrayCreateIterator,
-  typeArrayInsertGenerics,
-  typeArrayDelete,
-  typeArrayMap,
+  typeListGet,
+  typeListToArray,
+  typeListForEach,
+  typeListCreateIterator,
+  typeListInsertGenerics,
+  typeListDelete,
+  typeListMap,
  YArrayRefID,
  callTypeObservers,
  transact,
-  Y, Transaction, ItemType, // eslint-disable-line
+  Doc, Transaction, Item // eslint-disable-line
 } from '../internals.js'

 import * as decoding from 'lib0/decoding.js' // eslint-disable-line
@@ -58,17 +58,21 @@ export class YArray extends AbstractType {
   * * This type is sent to other client
   * * Observer functions are fired
   *
-   * @param {Y} y The Yjs instance
-   * @param {ItemType} item
+   * @param {Doc} y The Yjs instance
+   * @param {Item} item
   *
   * @private
   */
  _integrate (y, item) {
    super._integrate(y, item)
-    // @ts-ignore
-    this.insert(0, this._prelimContent)
+    this.insert(0, /** @type {Array} */ (this._prelimContent))
    this._prelimContent = null
  }
+
+  _copy () {
+    return new YArray()
+  }
+
  get length () {
    return this._prelimContent === null ? this._length : this._prelimContent.length
  }
@@ -84,6 +88,57 @@ export class YArray extends AbstractType {
    callTypeObservers(this, transaction, new YArrayEvent(this, transaction))
  }

+  /**
+   * Inserts new content at an index.
+   *
+   * Important: This function expects an array of content. Not just a content
+   * object. The reason for this "weirdness" is that inserting several elements
+   * is very efficient when it is done as a single operation.
+   *
+   * @example
+   *  // Insert character 'a' at position 0
+   *  yarray.insert(0, ['a'])
+   *  // Insert numbers 1, 2 at position 1
+   *  yarray.insert(1, [1, 2])
+   *
+   * @param {number} index The index to insert content at.
+   * @param {Array<T>} content The array of content
+   */
+  insert (index, content) {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
+        typeListInsertGenerics(transaction, this, index, content)
+      })
+    } else {
+      /** @type {Array} */ (this._prelimContent).splice(index, 0, ...content)
+    }
+  }
+
+  /**
+   * Appends content to this YArray.
+   *
+   * @param {Array<T>} content Array of content to append.
+   */
+  push (content) {
+    this.insert(this.length, content)
+  }
+
+  /**
+   * Deletes elements starting from an index.
+   *
+   * @param {number} index Index at which to start deleting elements
+   * @param {number} length The number of elements to remove. Defaults to 1.
+   */
+  delete (index, length = 1) {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
+        typeListDelete(transaction, this, index, length)
+      })
+    } else {
+      /** @type {Array} */ (this._prelimContent).splice(index, length)
+    }
+  }
+
  /**
   * Returns the i-th element from a YArray.
   *
@@ -91,7 +146,7 @@ export class YArray extends AbstractType {
   * @return {T}
   */
  get (index) {
-    return typeArrayGet(this, index)
+    return typeListGet(this, index)
  }

  /**
@@ -100,7 +155,7 @@ export class YArray extends AbstractType {
   * @return {Array<T>}
   */
  toArray () {
-    return typeArrayToArray(this)
+    return typeListToArray(this)
  }

  /**
@@ -122,77 +177,23 @@ export class YArray extends AbstractType {
   *                 callback function
   */
  map (f) {
-    // @ts-ignore
-    return typeArrayMap(this, f)
+    return typeListMap(this, /** @type {any} */ (f))
  }

  /**
   * Executes a provided function on once on overy element of this YArray.
   *
-   * @param {function(T,number):void} f A function to execute on every element of this YArray.
+   * @param {function(T,number,YArray<T>):void} f A function to execute on every element of this YArray.
   */
  forEach (f) {
-    typeArrayForEach(this, f)
+    typeListForEach(this, f)
  }

  /**
   * @return {IterableIterator<T>}
   */
  [Symbol.iterator] () {
-    return typeArrayCreateIterator(this)
-  }
-
-  /**
-   * Deletes elements starting from an index.
-   *
-   * @param {number} index Index at which to start deleting elements
-   * @param {number} length The number of elements to remove. Defaults to 1.
-   */
-  delete (index, length = 1) {
-    if (this._y !== null) {
-      transact(this._y, transaction => {
-        typeArrayDelete(transaction, this, index, length)
-      })
-    } else {
-      // @ts-ignore _prelimContent is defined because this is not yet integrated
-      this._prelimContent.splice(index, length)
-    }
-  }
-
-  /**
-   * Inserts new content at an index.
-   *
-   * Important: This function expects an array of content. Not just a content
-   * object. The reason for this "weirdness" is that inserting several elements
-   * is very efficient when it is done as a single operation.
-   *
-   * @example
-   *  // Insert character 'a' at position 0
-   *  yarray.insert(0, ['a'])
-   *  // Insert numbers 1, 2 at position 1
-   *  yarray.insert(1, [1, 2])
-   *
-   * @param {number} index The index to insert content at.
-   * @param {Array<T>} content The array of content
-   */
-  insert (index, content) {
-    if (this._y !== null) {
-      transact(this._y, transaction => {
-        typeArrayInsertGenerics(transaction, this, index, content)
-      })
-    } else {
-      // @ts-ignore _prelimContent is defined because this is not yet integrated
-      this._prelimContent.splice(index, 0, ...content)
-    }
-  }
-
-  /**
-   * Appends content to this YArray.
-   *
-   * @param {Array<T>} content Array of content to append.
-   */
-  push (content) {
-    this.insert(this.length, content)
+    return typeListCreateIterator(this)
  }

  /**
--- a/src/types/YMap.js
+++ b/src/types/YMap.js
@@ -14,7 +14,7 @@ import {
  YMapRefID,
  callTypeObservers,
  transact,
-  Y, Transaction, ItemType, // eslint-disable-line
+  Doc, Transaction, Item // eslint-disable-line
 } from '../internals.js'

 import * as encoding from 'lib0/encoding.js'
@@ -38,7 +38,7 @@ export class YMapEvent extends YEvent {
 }

 /**
- * @template T number|string|Object|Array|ArrayBuffer
+ * @template T number|string|Object|Array|Uint8Array
 * A shared Map implementation.
 *
 * @extends AbstractType<YMapEvent<T>>
@@ -60,19 +60,23 @@ export class YMap extends AbstractType {
   * * This type is sent to other client
   * * Observer functions are fired
   *
-   * @param {Y} y The Yjs instance
-   * @param {ItemType} item
+   * @param {Doc} y The Yjs instance
+   * @param {Item} item
   *
   * @private
   */
  _integrate (y, item) {
    super._integrate(y, item)
-    // @ts-ignore
-    for (let [key, value] of this._prelimContent) {
+    for (let [key, value] of /** @type {Map<string, any>} */ (this._prelimContent)) {
      this.set(key, value)
    }
    this._prelimContent = null
  }
+
+  _copy () {
+    return new YMap()
+  }
+
  /**
   * Creates YMapEvent and calls observers.
   *
@@ -97,7 +101,7 @@ export class YMap extends AbstractType {
    const map = {}
    for (let [key, item] of this._map) {
      if (!item.deleted) {
-        const v = item.getContent()[0]
+        const v = item.content.getContent()[item.length - 1]
        map[key] = v instanceof AbstractType ? v.toJSON() : v
      }
    }
@@ -107,18 +111,46 @@ export class YMap extends AbstractType {
  /**
   * Returns the keys for each element in the YMap Type.
   *
-   * @return {Iterator<string>}
+   * @return {IterableIterator<string>}
   */
  keys () {
-    return iterator.iteratorMap(createMapIterator(this._map), v => v[0])
+    return iterator.iteratorMap(createMapIterator(this._map), /** @param {any} v */ v => v[0])
  }
+
  /**
-   * Returns the value for each element in the YMap Type.
+   * Returns the keys for each element in the YMap Type.
   *
-   * @return {IterableIterator<T>}
+   * @return {IterableIterator<string>}
+   */
+  values () {
+    return iterator.iteratorMap(createMapIterator(this._map), /** @param {any} v */ v => v[1].content.getContent()[v[1].length - 1])
+  }
+
+  /**
+   * Returns an Iterator of [key, value] pairs
+   *
+   * @return {IterableIterator<any>}
   */
  entries () {
-    return iterator.iteratorMap(createMapIterator(this._map), v => v[1].getContent()[0])
+    return iterator.iteratorMap(createMapIterator(this._map), /** @param {any} v */ v => [v[0], v[1].content.getContent()[v[1].length - 1]])
+  }
+
+  /**
+   * Executes a provided function on once on overy key-value pair.
+   *
+   * @param {function(T,string,YMap<T>):void} f A function to execute on every element of this YArray.
+   */
+  forEach (f) {
+    /**
+     * @type {Object<string,T>}
+     */
+    const map = {}
+    for (let [key, item] of this._map) {
+      if (!item.deleted) {
+        f(item.content.getContent()[item.length - 1], key, this)
+      }
+    }
+    return map
  }

  /**
@@ -134,13 +166,12 @@ export class YMap extends AbstractType {
   * @param {string} key The key of the element to remove.
   */
  delete (key) {
-    if (this._y !== null) {
-      transact(this._y, transaction => {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
        typeMapDelete(transaction, this, key)
      })
    } else {
-      // @ts-ignore
-      this._prelimContent.delete(key)
+      /** @type {Map<string, any>} */ (this._prelimContent).delete(key)
    }
  }

@@ -151,13 +182,12 @@ export class YMap extends AbstractType {
   * @param {T} value The value of the element to add
   */
  set (key, value) {
-    if (this._y !== null) {
-      transact(this._y, transaction => {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
        typeMapSet(transaction, this, key, value)
      })
    } else {
-      // @ts-ignore
-      this._prelimContent.set(key, value)
+      /** @type {Map<string, any>} */ (this._prelimContent).set(key, value)
    }
    return value
  }
@@ -169,8 +199,7 @@ export class YMap extends AbstractType {
   * @return {T|undefined}
   */
  get (key) {
-    // @ts-ignore
-    return typeMapGet(this, key)
+    return /** @type {any} */ (typeMapGet(this, key))
  }

  /**
--- a/src/types/YText.js
+++ b/src/types/YText.js
@@ -5,9 +5,6 @@

 import {
  YEvent,
-  ItemEmbed,
-  ItemString,
-  ItemFormat,
  AbstractType,
  nextID,
  createID,
@@ -16,7 +13,10 @@ import {
  YTextRefID,
  callTypeObservers,
  transact,
-  Y, ItemType, AbstractItem, Snapshot, StructStore, Transaction // eslint-disable-line
+  ContentEmbed,
+  ContentFormat,
+  ContentString,
+  Doc, Item, Snapshot, StructStore, Transaction // eslint-disable-line
 } from '../internals.js'

 import * as decoding from 'lib0/decoding.js' // eslint-disable-line
@@ -24,8 +24,8 @@ import * as encoding from 'lib0/encoding.js'

 export class ItemListPosition {
  /**
-   * @param {AbstractItem|null} left
-   * @param {AbstractItem|null} right
+   * @param {Item|null} left
+   * @param {Item|null} right
   */
  constructor (left, right) {
    this.left = left
@@ -35,8 +35,8 @@ export class ItemListPosition {

 export class ItemTextListPosition extends ItemListPosition {
  /**
-   * @param {AbstractItem|null} left
-   * @param {AbstractItem|null} right
+   * @param {Item|null} left
+   * @param {Item|null} right
   * @param {Map<string,any>} currentAttributes
   */
  constructor (left, right, currentAttributes) {
@@ -47,8 +47,8 @@ export class ItemTextListPosition extends ItemListPosition {

 export class ItemInsertionResult extends ItemListPosition {
  /**
-   * @param {AbstractItem|null} left
-   * @param {AbstractItem|null} right
+   * @param {Item|null} left
+   * @param {Item|null} right
   * @param {Map<string,any>} negatedAttributes
   */
  constructor (left, right, negatedAttributes) {
@@ -61,8 +61,8 @@ export class ItemInsertionResult extends ItemListPosition {
 * @param {Transaction} transaction
 * @param {StructStore} store
 * @param {Map<string,any>} currentAttributes
- * @param {AbstractItem|null} left
- * @param {AbstractItem|null} right
+ * @param {Item|null} left
+ * @param {Item|null} right
 * @param {number} count
 * @return {ItemTextListPosition}
 *
@@ -71,9 +71,9 @@ export class ItemInsertionResult extends ItemListPosition {
 */
 const findNextPosition = (transaction, store, currentAttributes, left, right, count) => {
  while (right !== null && count > 0) {
-    switch (right.constructor) {
-      case ItemEmbed:
-      case ItemString:
+    switch (right.content.constructor) {
+      case ContentEmbed:
+      case ContentString:
        if (!right.deleted) {
          if (count < right.length) {
            // split right
@@ -82,10 +82,9 @@ const findNextPosition = (transaction, store, currentAttributes, left, right, co
          count -= right.length
        }
        break
-      case ItemFormat:
+      case ContentFormat:
        if (!right.deleted) {
-          // @ts-ignore right is ItemFormat
-          updateCurrentAttributes(currentAttributes, right)
+          updateCurrentAttributes(currentAttributes, /** @type {ContentFormat} */ (right.content))
        }
        break
    }
@@ -117,8 +116,8 @@ const findPosition = (transaction, store, parent, index) => {
 *
 * @param {Transaction} transaction
 * @param {AbstractType<any>} parent
- * @param {AbstractItem|null} left
- * @param {AbstractItem|null} right
+ * @param {Item|null} left
+ * @param {Item|null} right
 * @param {Map<string,any>} negatedAttributes
 * @return {ItemListPosition}
 *
@@ -130,36 +129,33 @@ const insertNegatedAttributes = (transaction, parent, left, right, negatedAttrib
  while (
    right !== null && (
      right.deleted === true || (
-        right.constructor === ItemFormat &&
-        // @ts-ignore right is ItemFormat
-        (negatedAttributes.get(right.key) === right.value)
+        right.content.constructor === ContentFormat &&
+        (negatedAttributes.get(/** @type {ContentFormat} */ (right.content).key) === /** @type {ContentFormat} */ (right.content).value)
      )
    )
  ) {
    if (!right.deleted) {
-      // @ts-ignore right is ItemFormat
-      negatedAttributes.delete(right.key)
+      negatedAttributes.delete(/** @type {ContentFormat} */ (right.content).key)
    }
    left = right
    right = right.right
  }
  for (let [key, val] of negatedAttributes) {
-    left = new ItemFormat(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, null, key, val)
+    left = new Item(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, null, new ContentFormat(key, val))
    left.integrate(transaction)
  }
-  return {left, right}
+  return { left, right }
 }

 /**
 * @param {Map<string,any>} currentAttributes
- * @param {ItemFormat} item
+ * @param {ContentFormat} format
 *
 * @private
 * @function
 */
-const updateCurrentAttributes = (currentAttributes, item) => {
-  const value = item.value
-  const key = item.key
+const updateCurrentAttributes = (currentAttributes, format) => {
+  const { key, value } = format
  if (value === null) {
    currentAttributes.delete(key)
  } else {
@@ -168,8 +164,8 @@ const updateCurrentAttributes = (currentAttributes, item) => {
 }

 /**
- * @param {AbstractItem|null} left
- * @param {AbstractItem|null} right
+ * @param {Item|null} left
+ * @param {Item|null} right
 * @param {Map<string,any>} currentAttributes
 * @param {Object<string,any>} attributes
 * @return {ItemListPosition}
@@ -184,11 +180,9 @@ const minimizeAttributeChanges = (left, right, currentAttributes, attributes) =>
      break
    } else if (right.deleted) {
      // continue
-    // @ts-ignore right is ItemFormat
-    } else if (right.constructor === ItemFormat && (attributes[right.key] || null) === right.value) {
+    } else if (right.content.constructor === ContentFormat && (attributes[(/** @type {ContentFormat} */ (right.content)).key] || null) === /** @type {ContentFormat} */ (right.content).value) {
      // found a format, update currentAttributes and continue
-      // @ts-ignore right is ItemFormat
-      updateCurrentAttributes(currentAttributes, right)
+      updateCurrentAttributes(currentAttributes, /** @type {ContentFormat} */ (right.content))
    } else {
      break
    }
@@ -201,8 +195,8 @@ const minimizeAttributeChanges = (left, right, currentAttributes, attributes) =>
 /**
 * @param {Transaction} transaction
 * @param {AbstractType<any>} parent
- * @param {AbstractItem|null} left
- * @param {AbstractItem|null} right
+ * @param {Item|null} left
+ * @param {Item|null} right
 * @param {Map<string,any>} currentAttributes
 * @param {Object<string,any>} attributes
 * @return {ItemInsertionResult}
@@ -215,11 +209,11 @@ const insertAttributes = (transaction, parent, left, right, currentAttributes, a
  // insert format-start items
  for (let key in attributes) {
    const val = attributes[key]
-    const currentVal = currentAttributes.get(key)
+    const currentVal = currentAttributes.get(key) || null
    if (currentVal !== val) {
      // save negated attribute (set null if currentVal undefined)
-      negatedAttributes.set(key, currentVal || null)
-      left = new ItemFormat(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, null, key, val)
+      negatedAttributes.set(key, currentVal)
+      left = new Item(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, null, new ContentFormat(key, val))
      left.integrate(transaction)
    }
  }
@@ -229,10 +223,10 @@ const insertAttributes = (transaction, parent, left, right, currentAttributes, a
 /**
 * @param {Transaction} transaction
 * @param {AbstractType<any>} parent
- * @param {AbstractItem|null} left
- * @param {AbstractItem|null} right
+ * @param {Item|null} left
+ * @param {Item|null} right
 * @param {Map<string,any>} currentAttributes
- * @param {string} text
+ * @param {string|object} text
 * @param {Object<string,any>} attributes
 * @return {ItemListPosition}
 *
@@ -250,11 +244,8 @@ const insertText = (transaction, parent, left, right, currentAttributes, text, a
  left = insertPos.left
  right = insertPos.right
  // insert content
-  if (text.constructor === String) {
-    left = new ItemString(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, null, text)
-  } else {
-    left = new ItemEmbed(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, null, text)
-  }
+  const content = text.constructor === String ? new ContentString(text) : new ContentEmbed(text)
+  left = new Item(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, null, content)
  left.integrate(transaction)
  return insertNegatedAttributes(transaction, parent, left, insertPos.right, insertPos.negatedAttributes)
 }
@@ -262,8 +253,8 @@ const insertText = (transaction, parent, left, right, currentAttributes, text, a
 /**
 * @param {Transaction} transaction
 * @param {AbstractType<any>} parent
- * @param {AbstractItem|null} left
- * @param {AbstractItem|null} right
+ * @param {Item|null} left
+ * @param {Item|null} right
 * @param {Map<string,any>} currentAttributes
 * @param {number} length
 * @param {Object<string,any>} attributes
@@ -282,28 +273,24 @@ const formatText = (transaction, parent, left, right, currentAttributes, length,
  // delete all formats with attributes[format.key] != null
  while (length > 0 && right !== null) {
    if (right.deleted === false) {
-      switch (right.constructor) {
-        case ItemFormat:
-          // @ts-ignore right is ItemFormat
-          const attr = attributes[right.key]
+      switch (right.content.constructor) {
+        case ContentFormat:
+          const { key, value } = /** @type {ContentFormat} */ (right.content)
+          const attr = attributes[key]
          if (attr !== undefined) {
-            // @ts-ignore right is ItemFormat
-            if (attr === right.value) {
-              // @ts-ignore right is ItemFormat
-              negatedAttributes.delete(right.key)
+            if (attr === value) {
+              negatedAttributes.delete(key)
            } else {
-              // @ts-ignore right is ItemFormat
-              negatedAttributes.set(right.key, right.value)
+              negatedAttributes.set(key, value)
            }
            right.delete(transaction)
          }
-          // @ts-ignore right is ItemFormat
-          updateCurrentAttributes(currentAttributes, right)
+          updateCurrentAttributes(currentAttributes, /** @type {ContentFormat} */ (right.content))
          break
-        case ItemEmbed:
-        case ItemString:
+        case ContentEmbed:
+        case ContentString:
          if (length < right.length) {
-            getItemCleanStart(transaction, transaction.y.store, createID(right.id.client, right.id.clock + length))
+            getItemCleanStart(transaction, transaction.doc.store, createID(right.id.client, right.id.clock + length))
          }
          length -= right.length
          break
@@ -312,13 +299,24 @@ const formatText = (transaction, parent, left, right, currentAttributes, length,
    left = right
    right = right.right
  }
+  // Quill just assumes that the editor starts with a newline and that it always
+  // ends with a newline. We only insert that newline when a new newline is
+  // inserted - i.e when length is bigger than type.length
+  if (length > 0) {
+    let newlines = ''
+    for (; length > 0; length--) {
+      newlines += '\n'
+    }
+    left = new Item(nextID(transaction), left, left === null ? null : left.lastId, right, right === null ? null : right.id, parent, null, new ContentString(newlines))
+    left.integrate(transaction)
+  }
  return insertNegatedAttributes(transaction, parent, left, right, negatedAttributes)
 }

 /**
 * @param {Transaction} transaction
- * @param {AbstractItem|null} left
- * @param {AbstractItem|null} right
+ * @param {Item|null} left
+ * @param {Item|null} right
 * @param {Map<string,any>} currentAttributes
 * @param {number} length
 * @return {ItemListPosition}
@@ -329,15 +327,14 @@ const formatText = (transaction, parent, left, right, currentAttributes, length,
 const deleteText = (transaction, left, right, currentAttributes, length) => {
  while (length > 0 && right !== null) {
    if (right.deleted === false) {
-      switch (right.constructor) {
-        case ItemFormat:
-          // @ts-ignore right is ItemFormat
-          updateCurrentAttributes(currentAttributes, right)
+      switch (right.content.constructor) {
+        case ContentFormat:
+          updateCurrentAttributes(currentAttributes, /** @type {ContentFormat} */ (right.content))
          break
-        case ItemEmbed:
-        case ItemString:
+        case ContentEmbed:
+        case ContentString:
          if (length < right.length) {
-            getItemCleanStart(transaction, transaction.y.store, createID(right.id.client, right.id.clock + length))
+            getItemCleanStart(transaction, transaction.doc.store, createID(right.id.client, right.id.clock + length))
          }
          length -= right.length
          right.delete(transaction)
@@ -388,7 +385,7 @@ const deleteText = (transaction, left, right, currentAttributes, length) => {
 /**
 * Event that describes the changes on a YText type.
 */
-class YTextEvent extends YEvent {
+export class YTextEvent extends YEvent {
  /**
   * @param {YText} ytext
   * @param {Transaction} transaction
@@ -411,13 +408,10 @@ class YTextEvent extends YEvent {
   */
  get delta () {
    if (this._delta === null) {
-      const y = this.target._y
-      // @ts-ignore
+      const y = /** @type {Doc} */ (this.target.doc)
+      this._delta = []
      transact(y, transaction => {
-        /**
-         * @type {Array<DeltaItem>}
-         */
-        const delta = []
+        const delta = /** @type {Array<DeltaItem>} */ (this._delta)
        const currentAttributes = new Map() // saves all current attributes for insert
        const oldAttributes = new Map()
        let item = this.target._start
@@ -432,7 +426,6 @@ class YTextEvent extends YEvent {
        let insert = ''
        let retain = 0
        let deleteLen = 0
-        this._delta = delta
        const addOp = () => {
          if (action !== null) {
            /**
@@ -472,14 +465,15 @@ class YTextEvent extends YEvent {
          }
        }
        while (item !== null) {
-          switch (item.constructor) {
-            case ItemEmbed:
+          switch (item.content.constructor) {
+            case ContentEmbed:
              if (this.adds(item)) {
-                addOp()
-                action = 'insert'
-                // @ts-ignore item is ItemFormat
-                insert = item.embed
-                addOp()
+                if (!this.deletes(item)) {
+                  addOp()
+                  action = 'insert'
+                  insert = /** @type {ContentEmbed} */ (item.content).embed
+                  addOp()
+                }
              } else if (this.deletes(item)) {
                if (action !== 'delete') {
                  addOp()
@@ -494,14 +488,15 @@ class YTextEvent extends YEvent {
                retain += 1
              }
              break
-            case ItemString:
+            case ContentString:
              if (this.adds(item)) {
-                if (action !== 'insert') {
-                  addOp()
-                  action = 'insert'
+                if (!this.deletes(item)) {
+                  if (action !== 'insert') {
+                    addOp()
+                    action = 'insert'
+                  }
+                  insert += /** @type {ContentString} */ (item.content).str
                }
-                // @ts-ignore
-                insert += item.string
              } else if (this.deletes(item)) {
                if (action !== 'delete') {
                  addOp()
@@ -516,57 +511,45 @@ class YTextEvent extends YEvent {
                retain += item.length
              }
              break
-            case ItemFormat:
+            case ContentFormat:
+              const { key, value } = /** @type {ContentFormat} */ (item.content)
              if (this.adds(item)) {
-                // @ts-ignore item is ItemFormat
-                const curVal = currentAttributes.get(item.key) || null
-                // @ts-ignore item is ItemFormat
-                if (curVal !== item.value) {
-                  if (action === 'retain') {
-                    addOp()
-                  }
-                  // @ts-ignore item is ItemFormat
-                  if (item.value === (oldAttributes.get(item.key) || null)) {
-                    // @ts-ignore item is ItemFormat
-                    delete attributes[item.key]
-                  } else {
-                    // @ts-ignore item is ItemFormat
-                    attributes[item.key] = item.value
-                  }
-                } else {
-                  item.delete(transaction)
-                }
-              } else if (this.deletes(item)) {
-                // @ts-ignore item is ItemFormat
-                oldAttributes.set(item.key, item.value)
-                // @ts-ignore item is ItemFormat
-                const curVal = currentAttributes.get(item.key) || null
-                // @ts-ignore item is ItemFormat
-                if (curVal !== item.value) {
-                  if (action === 'retain') {
-                    addOp()
-                  }
-                  // @ts-ignore item is ItemFormat
-                  attributes[item.key] = curVal
-                }
-              } else if (!item.deleted) {
-                // @ts-ignore item is ItemFormat
-                oldAttributes.set(item.key, item.value)
-                // @ts-ignore item is ItemFormat
-                const attr = attributes[item.key]
-                if (attr !== undefined) {
-                  // @ts-ignore item is ItemFormat
-                  if (attr !== item.value) {
+                if (!this.deletes(item)) {
+                  const curVal = currentAttributes.get(key) || null
+                  if (curVal !== value) {
                    if (action === 'retain') {
                      addOp()
                    }
-                    // @ts-ignore item is ItemFormat
-                    if (item.value === null) {
-                      // @ts-ignore item is ItemFormat
-                      attributes[item.key] = item.value
+                    if (value === (oldAttributes.get(key) || null)) {
+                      delete attributes[key]
                    } else {
-                      // @ts-ignore item is ItemFormat
-                      delete attributes[item.key]
+                      attributes[key] = value
+                    }
+                  } else {
+                    item.delete(transaction)
+                  }
+                }
+              } else if (this.deletes(item)) {
+                oldAttributes.set(key, value)
+                const curVal = currentAttributes.get(key) || null
+                if (curVal !== value) {
+                  if (action === 'retain') {
+                    addOp()
+                  }
+                  attributes[key] = curVal
+                }
+              } else if (!item.deleted) {
+                oldAttributes.set(key, value)
+                const attr = attributes[key]
+                if (attr !== undefined) {
+                  if (attr !== value) {
+                    if (action === 'retain') {
+                      addOp()
+                    }
+                    if (value === null) {
+                      attributes[key] = value
+                    } else {
+                      delete attributes[key]
                    }
                  } else {
                    item.delete(transaction)
@@ -577,26 +560,24 @@ class YTextEvent extends YEvent {
                if (action === 'insert') {
                  addOp()
                }
-                // @ts-ignore item is ItemFormat
-                updateCurrentAttributes(currentAttributes, item)
+                updateCurrentAttributes(currentAttributes, /** @type {ContentFormat} */ (item.content))
              }
              break
          }
          item = item.right
        }
        addOp()
-        while (this._delta.length > 0) {
-          let lastOp = this._delta[this._delta.length - 1]
+        while (delta.length > 0) {
+          let lastOp = delta[delta.length - 1]
          if (lastOp.retain !== undefined && lastOp.attributes === undefined) {
            // retain delta's if they don't assign attributes
-            this._delta.pop()
+            delta.pop()
          } else {
            break
          }
        }
      })
    }
-    // @ts-ignore _delta is defined above
    return this._delta
  }
 }
@@ -617,10 +598,11 @@ export class YText extends AbstractType {
  constructor (string) {
    super()
    /**
-     * @type {Array<string>?}
+     * Array of pending operations on this type
+     * @type {Array<function():void>?}
     * @private
     */
-    this._prelimContent = string !== undefined ? [string] : []
+    this._pending = string !== undefined ? [() => this.insert(0, string)] : []
  }

  get length () {
@@ -628,16 +610,23 @@ export class YText extends AbstractType {
  }

  /**
-   * @param {Y} y
-   * @param {ItemType} item
+   * @param {Doc} y
+   * @param {Item} item
   *
   * @private
   */
  _integrate (y, item) {
    super._integrate(y, item)
-    // @ts-ignore this._prelimContent is still defined
-    this.insert(0, this._prelimContent.join(''))
-    this._prelimContent = null
+    try {
+      /** @type {Array<function>} */ (this._pending).forEach(f => f())
+    } catch (e) {
+      console.error(e)
+    }
+    this._pending = null
+  }
+
+  _copy () {
+    return new YText()
  }

  /**
@@ -652,10 +641,6 @@ export class YText extends AbstractType {
    callTypeObservers(this, transaction, new YTextEvent(this, transaction))
  }

-  toDom () {
-    return document.createTextNode(this.toString())
-  }
-
  /**
   * Returns the unformatted string representation of this YText type.
   *
@@ -664,53 +649,18 @@ export class YText extends AbstractType {
  toString () {
    let str = ''
    /**
-     * @type {AbstractItem|null}
+     * @type {Item|null}
     */
    let n = this._start
    while (n !== null) {
-      if (!n.deleted && n.countable && n.constructor === ItemString) {
-        // @ts-ignore
-        str += n.string
+      if (!n.deleted && n.countable && n.content.constructor === ContentString) {
+        str += /** @type {ContentString} */ (n.content).str
      }
      n = n.right
    }
    return str
  }

-  toDomString () {
-    // @ts-ignore
-    return this.toDelta().map(delta => {
-      const nestedNodes = []
-      for (let nodeName in delta.attributes) {
-        const attrs = []
-        for (let key in delta.attributes[nodeName]) {
-          attrs.push({ key, value: delta.attributes[nodeName][key] })
-        }
-        // sort attributes to get a unique order
-        attrs.sort((a, b) => a.key < b.key ? -1 : 1)
-        nestedNodes.push({ nodeName, attrs })
-      }
-      // sort node order to get a unique order
-      nestedNodes.sort((a, b) => a.nodeName < b.nodeName ? -1 : 1)
-      // now convert to dom string
-      let str = ''
-      for (let i = 0; i < nestedNodes.length; i++) {
-        const node = nestedNodes[i]
-        str += `<${node.nodeName}`
-        for (let j = 0; j < node.attrs.length; j++) {
-          const attr = node.attrs[i]
-          str += ` ${attr.key}="${attr.value}"`
-        }
-        str += '>'
-      }
-      str += delta.insert
-      for (let i = nestedNodes.length - 1; i >= 0; i--) {
-        str += `</${nestedNodes[i].nodeName}>`
-      }
-      return str
-    })
-  }
-
  /**
   * Apply a {@link Delta} on this shared YText type.
   *
@@ -719,8 +669,8 @@ export class YText extends AbstractType {
   * @public
   */
  applyDelta (delta) {
-    if (this._y !== null) {
-      transact(this._y, transaction => {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
        /**
         * @type {ItemListPosition}
         */
@@ -729,7 +679,15 @@ export class YText extends AbstractType {
        for (let i = 0; i < delta.length; i++) {
          const op = delta[i]
          if (op.insert !== undefined) {
-            pos = insertText(transaction, this, pos.left, pos.right, currentAttributes, op.insert, op.attributes || {})
+            // Quill assumes that the content starts with an empty paragraph.
+            // Yjs/Y.Text assumes that it starts empty. We always hide that
+            // there is a newline at the end of the content.
+            // If we omit this step, clients will see a different number of
+            // paragraphs, but nothing bad will happen.
+            const ins = (typeof op.insert === 'string' && i === delta.length - 1 && pos.right === null && op.insert.slice(-1) === '\n') ? op.insert.slice(0, -1) : op.insert
+            if (typeof ins !== 'string' || ins.length > 0) {
+              pos = insertText(transaction, this, pos.left, pos.right, currentAttributes, ins, op.attributes || {})
+            }
          } else if (op.retain !== undefined) {
            pos = formatText(transaction, this, pos.left, pos.right, currentAttributes, op.retain, op.attributes || {})
          } else if (op.delete !== undefined) {
@@ -737,6 +695,8 @@ export class YText extends AbstractType {
          }
        }
      })
+    } else {
+      /** @type {Array<function>} */ (this._pending).push(() => this.applyDelta(delta))
    }
  }

@@ -756,10 +716,6 @@ export class YText extends AbstractType {
    const ops = []
    const currentAttributes = new Map()
    let str = ''
-    /**
-     * @type {AbstractItem|null}
-     */
-    // @ts-ignore
    let n = this._start
    function packStr () {
      if (str.length > 0) {
@@ -786,8 +742,8 @@ export class YText extends AbstractType {
    }
    while (n !== null) {
      if (isVisible(n, snapshot) || (prevSnapshot !== undefined && isVisible(n, prevSnapshot))) {
-        switch (n.constructor) {
-          case ItemString:
+        switch (n.content.constructor) {
+          case ContentString:
            const cur = currentAttributes.get('ychange')
            if (snapshot !== undefined && !isVisible(n, snapshot)) {
              if (cur === undefined || cur.user !== n.id.client || cur.state !== 'removed') {
@@ -803,13 +759,17 @@ export class YText extends AbstractType {
              packStr()
              currentAttributes.delete('ychange')
            }
-            // @ts-ignore
-            str += n.string
+            str += /** @type {ContentString} */ (n.content).str
            break
-          case ItemFormat:
+          case ContentEmbed:
            packStr()
-            // @ts-ignore
-            updateCurrentAttributes(currentAttributes, n)
+            ops.push({
+              insert: /** @type {ContentEmbed} */ (n.content).embed
+            })
+            break
+          case ContentFormat:
+            packStr()
+            updateCurrentAttributes(currentAttributes, /** @type {ContentFormat} */ (n.content))
            break
        }
      }
@@ -833,12 +793,14 @@ export class YText extends AbstractType {
    if (text.length <= 0) {
      return
    }
-    const y = this._y
+    const y = this.doc
    if (y !== null) {
      transact(y, transaction => {
-        const {left, right, currentAttributes} = findPosition(transaction, y.store, this, index)
+        const { left, right, currentAttributes } = findPosition(transaction, y.store, this, index)
        insertText(transaction, this, left, right, currentAttributes, text, attributes)
      })
+    } else {
+      /** @type {Array<function>} */ (this._pending).push(() => this.insert(index, text, attributes))
    }
  }

@@ -856,12 +818,14 @@ export class YText extends AbstractType {
    if (embed.constructor !== Object) {
      throw new Error('Embed must be an Object')
    }
-    const y = this._y
+    const y = this.doc
    if (y !== null) {
      transact(y, transaction => {
        const { left, right, currentAttributes } = findPosition(transaction, y.store, this, index)
        insertText(transaction, this, left, right, currentAttributes, embed, attributes)
      })
+    } else {
+      /** @type {Array<function>} */ (this._pending).push(() => this.insertEmbed(index, embed, attributes))
    }
  }

@@ -877,12 +841,14 @@ export class YText extends AbstractType {
    if (length === 0) {
      return
    }
-    const y = this._y
+    const y = this.doc
    if (y !== null) {
      transact(y, transaction => {
        const { left, right, currentAttributes } = findPosition(transaction, y.store, this, index)
        deleteText(transaction, left, right, currentAttributes, length)
      })
+    } else {
+      /** @type {Array<function>} */ (this._pending).push(() => this.delete(index, length))
    }
  }

@@ -897,7 +863,7 @@ export class YText extends AbstractType {
   * @public
   */
  format (index, length, attributes) {
-    const y = this._y
+    const y = this.doc
    if (y !== null) {
      transact(y, transaction => {
        let { left, right, currentAttributes } = findPosition(transaction, y.store, this, index)
@@ -906,6 +872,8 @@ export class YText extends AbstractType {
        }
        formatText(transaction, this, left, right, currentAttributes, length, attributes)
      })
+    } else {
+      /** @type {Array<function>} */ (this._pending).push(() => this.format(index, length, attributes))
    }
  }

--- a/src/types/YXmlElement.js
+++ b/src/types/YXmlElement.js
@@ -1,244 +1,19 @@
-/**
- * @module YXml
- */

 import {
-  YXmlEvent,
-  AbstractType,
-  typeArrayMap,
-  typeArrayForEach,
+  YXmlFragment,
+  transact,
+  typeMapDelete,
+  typeMapSet,
  typeMapGet,
  typeMapGetAll,
-  typeArrayInsertGenerics,
-  typeArrayDelete,
-  typeMapSet,
-  typeMapDelete,
+  typeListForEach,
  YXmlElementRefID,
-  callTypeObservers,
-  transact,
-  Y, Transaction, ItemType, YXmlText, YXmlHook, Snapshot // eslint-disable-line
+  Snapshot, Doc, Item // eslint-disable-line
 } from '../internals.js'

 import * as encoding from 'lib0/encoding.js'
 import * as decoding from 'lib0/decoding.js'

-/**
- * Define the elements to which a set of CSS queries apply.
- * {@link https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Selectors|CSS_Selectors}
- *
- * @example
- *   query = '.classSelector'
- *   query = 'nodeSelector'
- *   query = '#idSelector'
- *
- * @typedef {string} CSS_Selector
- */
-
-/**
- * Dom filter function.
- *
- * @callback domFilter
- * @param {string} nodeName The nodeName of the element
- * @param {Map} attributes The map of attributes.
- * @return {boolean} Whether to include the Dom node in the YXmlElement.
- */
-
-/**
- * Represents a subset of the nodes of a YXmlElement / YXmlFragment and a
- * position within them.
- *
- * Can be created with {@link YXmlFragment#createTreeWalker}
- *
- * @public
- * @implements {IterableIterator}
- */
-export class YXmlTreeWalker {
-  /**
-   * @param {YXmlFragment | YXmlElement} root
-   * @param {function(AbstractType<any>):boolean} [f]
-   */
-  constructor (root, f = () => true) {
-    this._filter = f
-    this._root = root
-    /**
-     * @type {ItemType | null}
-     */
-    // @ts-ignore
-    this._currentNode = root._start
-    this._firstCall = true
-  }
-
-  [Symbol.iterator] () {
-    return this
-  }
-  /**
-   * Get the next node.
-   *
-   * @return {IteratorResult<YXmlElement|YXmlText|YXmlHook>} The next node.
-   *
-   * @public
-   */
-  next () {
-    let n = this._currentNode
-    if (n !== null && (!this._firstCall || n.deleted || !this._filter(n.type))) { // if first call, we check if we can use the first item
-      do {
-        if (!n.deleted && (n.type.constructor === YXmlElement || n.type.constructor === YXmlFragment) && n.type._start !== null) {
-          // walk down in the tree
-          // @ts-ignore
-          n = n.type._start
-        } else {
-          // walk right or up in the tree
-          while (n !== null) {
-            if (n.right !== null) {
-              // @ts-ignore
-              n = n.right
-              break
-            } else if (n.parent === this._root) {
-              n = null
-            } else {
-              n = n.parent._item
-            }
-          }
-        }
-      } while (n !== null && (n.deleted || !this._filter(n.type)))
-    }
-    this._firstCall = false
-    this._currentNode = n
-    if (n === null) {
-      // @ts-ignore return undefined if done=true (the expected result)
-      return { value: undefined, done: true }
-    }
-    // @ts-ignore
-    return { value: n.type, done: false }
-  }
-}
-
-/**
- * Represents a list of {@link YXmlElement}.and {@link YXmlText} types.
- * A YxmlFragment is similar to a {@link YXmlElement}, but it does not have a
- * nodeName and it does not have attributes. Though it can be bound to a DOM
- * element - in this case the attributes and the nodeName are not shared.
- *
- * @public
- * @extends AbstractType<YXmlEvent>
- */
-export class YXmlFragment extends AbstractType {
-  /**
-   * Create a subtree of childNodes.
-   *
-   * @example
-   * const walker = elem.createTreeWalker(dom => dom.nodeName === 'div')
-   * for (let node in walker) {
-   *   // `node` is a div node
-   *   nop(node)
-   * }
-   *
-   * @param {function(AbstractType<any>):boolean} filter Function that is called on each child element and
-   *                          returns a Boolean indicating whether the child
-   *                          is to be included in the subtree.
-   * @return {YXmlTreeWalker} A subtree and a position within it.
-   *
-   * @public
-   */
-  createTreeWalker (filter) {
-    return new YXmlTreeWalker(this, filter)
-  }
-
-  /**
-   * Returns the first YXmlElement that matches the query.
-   * Similar to DOM's {@link querySelector}.
-   *
-   * Query support:
-   *   - tagname
-   * TODO:
-   *   - id
-   *   - attribute
-   *
-   * @param {CSS_Selector} query The query on the children.
-   * @return {YXmlElement|YXmlText|YXmlHook|null} The first element that matches the query or null.
-   *
-   * @public
-   */
-  querySelector (query) {
-    query = query.toUpperCase()
-    // @ts-ignore
-    const iterator = new YXmlTreeWalker(this, element => element.nodeName === query)
-    const next = iterator.next()
-    if (next.done) {
-      return null
-    } else {
-      return next.value
-    }
-  }
-
-  /**
-   * Returns all YXmlElements that match the query.
-   * Similar to Dom's {@link querySelectorAll}.
-   *
-   * @todo Does not yet support all queries. Currently only query by tagName.
-   *
-   * @param {CSS_Selector} query The query on the children
-   * @return {Array<YXmlElement|YXmlText|YXmlHook|null>} The elements that match this query.
-   *
-   * @public
-   */
-  querySelectorAll (query) {
-    query = query.toUpperCase()
-    // @ts-ignore
-    return Array.from(new YXmlTreeWalker(this, element => element.nodeName === query))
-  }
-
-  /**
-   * Creates YXmlEvent and calls observers.
-   * @private
-   *
-   * @param {Transaction} transaction
-   * @param {Set<null|string>} parentSubs Keys changed on this type. `null` if list was modified.
-   */
-  _callObserver (transaction, parentSubs) {
-    callTypeObservers(this, transaction, new YXmlEvent(this, parentSubs, transaction))
-  }
-
-  toString () {
-    return this.toDomString()
-  }
-
-  /**
-   * Get the string representation of all the children of this YXmlFragment.
-   *
-   * @return {string} The string representation of all children.
-   */
-  toDomString () {
-    return typeArrayMap(this, xml => xml.toDomString()).join('')
-  }
-
-  /**
-   * Creates a Dom Element that mirrors this YXmlElement.
-   *
-   * @param {Document} [_document=document] The document object (you must define
-   *                                        this when calling this method in
-   *                                        nodejs)
-   * @param {Object<string, any>} [hooks={}] Optional property to customize how hooks
-   *                                             are presented in the DOM
-   * @param {any} [binding] You should not set this property. This is
-   *                               used if DomBinding wants to create a
-   *                               association to the created DOM type.
-   * @return {Node} The {@link https://developer.mozilla.org/en-US/docs/Web/API/Element|Dom Element}
-   *
-   * @public
-   */
-  toDom (_document = document, hooks = {}, binding) {
-    const fragment = _document.createDocumentFragment()
-    if (binding !== undefined) {
-      binding._createAssociation(fragment, this)
-    }
-    typeArrayForEach(this, xmlType => {
-      fragment.insertBefore(xmlType.toDom(_document, hooks, binding), null)
-    })
-    return fragment
-  }
-}
-
 /**
 * An YXmlElement imitates the behavior of a
 * {@link https://developer.mozilla.org/en-US/docs/Web/API/Element|Dom Element}.
@@ -249,12 +24,7 @@ export class YXmlFragment extends AbstractType {
 export class YXmlElement extends YXmlFragment {
  constructor (nodeName = 'UNDEFINED') {
    super()
-    this.nodeName = nodeName.toUpperCase()
-    /**
-     * @type {Array<any>|null}
-     * @private
-     */
-    this._prelimContent = []
+    this.nodeName = nodeName
    /**
     * @type {Map<string, any>|null}
     * @private
@@ -269,20 +39,16 @@ export class YXmlElement extends YXmlFragment {
   * * This type is sent to other client
   * * Observer functions are fired
   *
-   * @param {Y} y The Yjs instance
-   * @param {ItemType} item
+   * @param {Doc} y The Yjs instance
+   * @param {Item} item
   * @private
   */
  _integrate (y, item) {
    super._integrate(y, item)
-    // @ts-ignore
-    this.insert(0, this._prelimContent)
-    this._prelimContent = null
-    // @ts-ignore
-    this._prelimAttrs.forEach((value, key) => {
+    ;(/** @type {Map<string, any>} */ (this._prelimAttrs)).forEach((value, key) => {
      this.setAttribute(key, value)
    })
-    this._prelimContent = null
+    this._prelimAttrs = null
  }

  /**
@@ -295,20 +61,16 @@ export class YXmlElement extends YXmlFragment {
    return new YXmlElement(this.nodeName)
  }

-  toString () {
-    return this.toDomString()
-  }
-
  /**
-   * Returns the string representation of this YXmlElement.
+   * Returns the XML serialization of this YXmlElement.
   * The attributes are ordered by attribute-name, so you can easily use this
   * method to compare YXmlElements
   *
-   * @return {String} The string representation of this type.
+   * @return {string} The string representation of this type.
   *
   * @public
   */
-  toDomString () {
+  toString () {
    const attrs = this.getAttributes()
    const stringBuilder = []
    const keys = []
@@ -323,7 +85,7 @@ export class YXmlElement extends YXmlFragment {
    }
    const nodeName = this.nodeName.toLocaleLowerCase()
    const attrsString = stringBuilder.length > 0 ? ' ' + stringBuilder.join(' ') : ''
-    return `<${nodeName}${attrsString}>${super.toDomString()}</${nodeName}>`
+    return `<${nodeName}${attrsString}>${super.toString()}</${nodeName}>`
  }

  /**
@@ -334,13 +96,12 @@ export class YXmlElement extends YXmlFragment {
   * @public
   */
  removeAttribute (attributeName) {
-    if (this._y !== null) {
-      transact(this._y, transaction => {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
        typeMapDelete(transaction, this, attributeName)
      })
    } else {
-      // @ts-ignore
-      this._prelimAttrs.delete(attributeName)
+      /** @type {Map<string,any>} */ (this._prelimAttrs).delete(attributeName)
    }
  }

@@ -353,13 +114,12 @@ export class YXmlElement extends YXmlFragment {
   * @public
   */
  setAttribute (attributeName, attributeValue) {
-    if (this._y !== null) {
-      transact(this._y, transaction => {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
        typeMapSet(transaction, this, attributeName, attributeValue)
      })
    } else {
-      // @ts-ignore
-      this._prelimAttrs.set(attributeName, attributeValue)
+      /** @type {Map<string, any>} */ (this._prelimAttrs).set(attributeName, attributeValue)
    }
  }

@@ -373,8 +133,7 @@ export class YXmlElement extends YXmlFragment {
   * @public
   */
  getAttribute (attributeName) {
-    // @ts-ignore
-    return typeMapGet(this, attributeName)
+    return /** @type {any} */ (typeMapGet(this, attributeName))
  }

  /**
@@ -389,44 +148,6 @@ export class YXmlElement extends YXmlFragment {
    return typeMapGetAll(this)
  }

-  /**
-   * Inserts new content at an index.
-   *
-   * @example
-   *  // Insert character 'a' at position 0
-   *  xml.insert(0, [new Y.XmlText('text')])
-   *
-   * @param {number} index The index to insert content at
-   * @param {Array<YXmlElement|YXmlText>} content The array of content
-   */
-  insert (index, content) {
-    if (this._y !== null) {
-      transact(this._y, transaction => {
-        typeArrayInsertGenerics(transaction, this, index, content)
-      })
-    } else {
-      // @ts-ignore _prelimContent is defined because this is not yet integrated
-      this._prelimContent.splice(index, 0, ...content)
-    }
-  }
-
-  /**
-   * Deletes elements starting from an index.
-   *
-   * @param {number} index Index at which to start deleting elements
-   * @param {number} [length=1] The number of elements to remove. Defaults to 1.
-   */
-  delete (index, length = 1) {
-    if (this._y !== null) {
-      transact(this._y, transaction => {
-        typeArrayDelete(transaction, this, index, length)
-      })
-    } else {
-      // @ts-ignore _prelimContent is defined because this is not yet integrated
-      this._prelimContent.splice(index, length)
-    }
-  }
-
  /**
   * Creates a Dom Element that mirrors this YXmlElement.
   *
@@ -442,14 +163,14 @@ export class YXmlElement extends YXmlFragment {
   *
   * @public
   */
-  toDom (_document = document, hooks = {}, binding) {
+  toDOM (_document = document, hooks = {}, binding) {
    const dom = _document.createElement(this.nodeName)
    let attrs = this.getAttributes()
    for (let key in attrs) {
      dom.setAttribute(key, attrs[key])
    }
-    typeArrayForEach(this, yxml => {
-      dom.appendChild(yxml.toDom(_document, hooks, binding))
+    typeListForEach(this, yxml => {
+      dom.appendChild(yxml.toDOM(_document, hooks, binding))
    })
    if (binding !== undefined) {
      binding._createAssociation(dom, this)
@@ -480,11 +201,3 @@ export class YXmlElement extends YXmlFragment {
 * @function
 */
 export const readYXmlElement = decoder => new YXmlElement(decoding.readVarString(decoder))
-/**
- * @param {decoding.Decoder} decoder
- * @return {YXmlFragment}
- *
- * @private
- * @function
- */
-export const readYXmlFragment = decoder => new YXmlFragment()
--- a/src/types/YXmlFragment.js
+++ b/src/types/YXmlFragment.js
@@ -0,0 +1,335 @@
+/**
+ * @module YXml
+ */
+
+import {
+  YXmlEvent,
+  YXmlElement,
+  AbstractType,
+  typeListMap,
+  typeListForEach,
+  typeListInsertGenerics,
+  typeListDelete,
+  typeListToArray,
+  YXmlFragmentRefID,
+  callTypeObservers,
+  transact,
+  Doc, ContentType, Transaction, Item, YXmlText, YXmlHook, Snapshot // eslint-disable-line
+} from '../internals.js'
+
+import * as encoding from 'lib0/encoding.js'
+import * as decoding from 'lib0/decoding.js' // eslint-disable-line
+
+/**
+ * Define the elements to which a set of CSS queries apply.
+ * {@link https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Selectors|CSS_Selectors}
+ *
+ * @example
+ *   query = '.classSelector'
+ *   query = 'nodeSelector'
+ *   query = '#idSelector'
+ *
+ * @typedef {string} CSS_Selector
+ */
+
+/**
+ * Dom filter function.
+ *
+ * @callback domFilter
+ * @param {string} nodeName The nodeName of the element
+ * @param {Map} attributes The map of attributes.
+ * @return {boolean} Whether to include the Dom node in the YXmlElement.
+ */
+
+/**
+ * Represents a subset of the nodes of a YXmlElement / YXmlFragment and a
+ * position within them.
+ *
+ * Can be created with {@link YXmlFragment#createTreeWalker}
+ *
+ * @public
+ * @implements {IterableIterator}
+ */
+export class YXmlTreeWalker {
+  /**
+   * @param {YXmlFragment | YXmlElement} root
+   * @param {function(AbstractType<any>):boolean} [f]
+   */
+  constructor (root, f = () => true) {
+    this._filter = f
+    this._root = root
+    /**
+     * @type {Item}
+     */
+    this._currentNode = /** @type {Item} */ (root._start)
+    this._firstCall = true
+  }
+
+  [Symbol.iterator] () {
+    return this
+  }
+  /**
+   * Get the next node.
+   *
+   * @return {IteratorResult<YXmlElement|YXmlText|YXmlHook>} The next node.
+   *
+   * @public
+   */
+  next () {
+    /**
+     * @type {Item|null}
+     */
+    let n = this._currentNode
+    let type = /** @type {ContentType} */ (n.content).type
+    if (n !== null && (!this._firstCall || n.deleted || !this._filter(type))) { // if first call, we check if we can use the first item
+      do {
+        type = /** @type {ContentType} */ (n.content).type
+        if (!n.deleted && (type.constructor === YXmlElement || type.constructor === YXmlFragment) && type._start !== null) {
+          // walk down in the tree
+          n = type._start
+        } else {
+          // walk right or up in the tree
+          while (n !== null) {
+            if (n.right !== null) {
+              n = n.right
+              break
+            } else if (n.parent === this._root) {
+              n = null
+            } else {
+              n = n.parent._item
+            }
+          }
+        }
+      } while (n !== null && (n.deleted || !this._filter(/** @type {ContentType} */ (n.content).type)))
+    }
+    this._firstCall = false
+    if (n === null) {
+      // @ts-ignore
+      return { value: undefined, done: true }
+    }
+    this._currentNode = n
+    return { value: /** @type {any} */ (n.content).type, done: false }
+  }
+}
+
+/**
+ * Represents a list of {@link YXmlElement}.and {@link YXmlText} types.
+ * A YxmlFragment is similar to a {@link YXmlElement}, but it does not have a
+ * nodeName and it does not have attributes. Though it can be bound to a DOM
+ * element - in this case the attributes and the nodeName are not shared.
+ *
+ * @public
+ * @extends AbstractType<YXmlEvent>
+ */
+export class YXmlFragment extends AbstractType {
+  constructor () {
+    super()
+    /**
+     * @type {Array<any>|null}
+     * @private
+     */
+    this._prelimContent = []
+  }
+  /**
+   * Integrate this type into the Yjs instance.
+   *
+   * * Save this struct in the os
+   * * This type is sent to other client
+   * * Observer functions are fired
+   *
+   * @param {Doc} y The Yjs instance
+   * @param {Item} item
+   * @private
+   */
+  _integrate (y, item) {
+    super._integrate(y, item)
+    this.insert(0, /** @type {Array} */ (this._prelimContent))
+    this._prelimContent = null
+  }
+
+  _copy () {
+    return new YXmlFragment()
+  }
+
+  /**
+   * Create a subtree of childNodes.
+   *
+   * @example
+   * const walker = elem.createTreeWalker(dom => dom.nodeName === 'div')
+   * for (let node in walker) {
+   *   // `node` is a div node
+   *   nop(node)
+   * }
+   *
+   * @param {function(AbstractType<any>):boolean} filter Function that is called on each child element and
+   *                          returns a Boolean indicating whether the child
+   *                          is to be included in the subtree.
+   * @return {YXmlTreeWalker} A subtree and a position within it.
+   *
+   * @public
+   */
+  createTreeWalker (filter) {
+    return new YXmlTreeWalker(this, filter)
+  }
+
+  /**
+   * Returns the first YXmlElement that matches the query.
+   * Similar to DOM's {@link querySelector}.
+   *
+   * Query support:
+   *   - tagname
+   * TODO:
+   *   - id
+   *   - attribute
+   *
+   * @param {CSS_Selector} query The query on the children.
+   * @return {YXmlElement|YXmlText|YXmlHook|null} The first element that matches the query or null.
+   *
+   * @public
+   */
+  querySelector (query) {
+    query = query.toUpperCase()
+    // @ts-ignore
+    const iterator = new YXmlTreeWalker(this, element => element.nodeName && element.nodeName.toUpperCase() === query)
+    const next = iterator.next()
+    if (next.done) {
+      return null
+    } else {
+      return next.value
+    }
+  }
+
+  /**
+   * Returns all YXmlElements that match the query.
+   * Similar to Dom's {@link querySelectorAll}.
+   *
+   * @todo Does not yet support all queries. Currently only query by tagName.
+   *
+   * @param {CSS_Selector} query The query on the children
+   * @return {Array<YXmlElement|YXmlText|YXmlHook|null>} The elements that match this query.
+   *
+   * @public
+   */
+  querySelectorAll (query) {
+    query = query.toUpperCase()
+    // @ts-ignore
+    return Array.from(new YXmlTreeWalker(this, element => element.nodeName && element.nodeName.toUpperCase() === query))
+  }
+
+  /**
+   * Creates YXmlEvent and calls observers.
+   * @private
+   *
+   * @param {Transaction} transaction
+   * @param {Set<null|string>} parentSubs Keys changed on this type. `null` if list was modified.
+   */
+  _callObserver (transaction, parentSubs) {
+    callTypeObservers(this, transaction, new YXmlEvent(this, parentSubs, transaction))
+  }
+
+  /**
+   * Get the string representation of all the children of this YXmlFragment.
+   *
+   * @return {string} The string representation of all children.
+   */
+  toString () {
+    return typeListMap(this, xml => xml.toString()).join('')
+  }
+
+  toJSON () {
+    return this.toString()
+  }
+
+  /**
+   * Creates a Dom Element that mirrors this YXmlElement.
+   *
+   * @param {Document} [_document=document] The document object (you must define
+   *                                        this when calling this method in
+   *                                        nodejs)
+   * @param {Object<string, any>} [hooks={}] Optional property to customize how hooks
+   *                                             are presented in the DOM
+   * @param {any} [binding] You should not set this property. This is
+   *                               used if DomBinding wants to create a
+   *                               association to the created DOM type.
+   * @return {Node} The {@link https://developer.mozilla.org/en-US/docs/Web/API/Element|Dom Element}
+   *
+   * @public
+   */
+  toDOM (_document = document, hooks = {}, binding) {
+    const fragment = _document.createDocumentFragment()
+    if (binding !== undefined) {
+      binding._createAssociation(fragment, this)
+    }
+    typeListForEach(this, xmlType => {
+      fragment.insertBefore(xmlType.toDOM(_document, hooks, binding), null)
+    })
+    return fragment
+  }
+
+  /**
+   * Inserts new content at an index.
+   *
+   * @example
+   *  // Insert character 'a' at position 0
+   *  xml.insert(0, [new Y.XmlText('text')])
+   *
+   * @param {number} index The index to insert content at
+   * @param {Array<YXmlElement|YXmlText>} content The array of content
+   */
+  insert (index, content) {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
+        typeListInsertGenerics(transaction, this, index, content)
+      })
+    } else {
+      // @ts-ignore _prelimContent is defined because this is not yet integrated
+      this._prelimContent.splice(index, 0, ...content)
+    }
+  }
+
+  /**
+   * Deletes elements starting from an index.
+   *
+   * @param {number} index Index at which to start deleting elements
+   * @param {number} [length=1] The number of elements to remove. Defaults to 1.
+   */
+  delete (index, length = 1) {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
+        typeListDelete(transaction, this, index, length)
+      })
+    } else {
+      // @ts-ignore _prelimContent is defined because this is not yet integrated
+      this._prelimContent.splice(index, length)
+    }
+  }
+  /**
+   * Transforms this YArray to a JavaScript Array.
+   *
+   * @return {Array<YXmlElement|YXmlText|YXmlHook>}
+   */
+  toArray () {
+    return typeListToArray(this)
+  }
+  /**
+   * Transform the properties of this type to binary and write it to an
+   * BinaryEncoder.
+   *
+   * This is called when this Item is sent to a remote peer.
+   *
+   * @private
+   * @param {encoding.Encoder} encoder The encoder to write data to.
+   */
+  _write (encoder) {
+    encoding.writeVarUint(encoder, YXmlFragmentRefID)
+  }
+}
+
+/**
+ * @param {decoding.Decoder} decoder
+ * @return {YXmlFragment}
+ *
+ * @private
+ * @function
+ */
+export const readYXmlFragment = decoder => new YXmlFragment()
--- a/src/types/YXmlHook.js
+++ b/src/types/YXmlHook.js
@@ -47,7 +47,7 @@ export class YXmlHook extends YMap {
   *
   * @public
   */
-  toDom (_document = document, hooks = {}, binding) {
+  toDOM (_document = document, hooks = {}, binding) {
    const hook = hooks[this.hookName]
    let dom
    if (hook !== undefined) {
--- a/src/types/YXmlText.js
+++ b/src/types/YXmlText.js
@@ -9,6 +9,9 @@ import * as decoding from 'lib0/decoding.js' // eslint-disable-line
 * simple formatting information like bold and italic.
 */
 export class YXmlText extends YText {
+  _copy () {
+    return new YXmlText()
+  }
  /**
   * Creates a Dom Element that mirrors this YXmlText.
   *
@@ -24,13 +27,52 @@ export class YXmlText extends YText {
   *
   * @public
   */
-  toDom (_document = document, hooks, binding) {
+  toDOM (_document = document, hooks, binding) {
    const dom = _document.createTextNode(this.toString())
    if (binding !== undefined) {
      binding._createAssociation(dom, this)
    }
    return dom
  }
+
+  toString () {
+    // @ts-ignore
+    return this.toDelta().map(delta => {
+      const nestedNodes = []
+      for (let nodeName in delta.attributes) {
+        const attrs = []
+        for (let key in delta.attributes[nodeName]) {
+          attrs.push({ key, value: delta.attributes[nodeName][key] })
+        }
+        // sort attributes to get a unique order
+        attrs.sort((a, b) => a.key < b.key ? -1 : 1)
+        nestedNodes.push({ nodeName, attrs })
+      }
+      // sort node order to get a unique order
+      nestedNodes.sort((a, b) => a.nodeName < b.nodeName ? -1 : 1)
+      // now convert to dom string
+      let str = ''
+      for (let i = 0; i < nestedNodes.length; i++) {
+        const node = nestedNodes[i]
+        str += `<${node.nodeName}`
+        for (let j = 0; j < node.attrs.length; j++) {
+          const attr = node.attrs[i]
+          str += ` ${attr.key}="${attr.value}"`
+        }
+        str += '>'
+      }
+      str += delta.insert
+      for (let i = nestedNodes.length - 1; i >= 0; i--) {
+        str += `</${nestedNodes[i].nodeName}>`
+      }
+      return str
+    }).join('')
+  }
+
+  toJSON () {
+    return this.toString()
+  }
+
  /**
   * @param {encoding.Encoder} encoder
   *
--- a/src/utils/DeleteSet.js
+++ b/src/utils/DeleteSet.js
@@ -3,7 +3,9 @@ import {
  findIndexSS,
  createID,
  getState,
-  AbstractItem, StructStore, Transaction, ID // eslint-disable-line
+  splitItem,
+  iterateStructs,
+  Item, GC, StructStore, Transaction, ID // eslint-disable-line
 } from '../internals.js'

 import * as math from 'lib0/math.js'
@@ -11,10 +13,7 @@ import * as map from 'lib0/map.js'
 import * as encoding from 'lib0/encoding.js'
 import * as decoding from 'lib0/decoding.js'

-/**
- * @private
- */
-class DeleteItem {
+export class DeleteItem {
  /**
   * @param {number} clock
   * @param {number} len
@@ -37,8 +36,6 @@ class DeleteItem {
 *   - This DeleteSet is send to other clients
 * - We do not create a DeleteSet when we send a sync message. The DeleteSet message is created directly from StructStore
 * - We read a DeleteSet as part of a sync/update message. In this case the DeleteSet is already sorted and merged.
- *
- * @private
 */
 export class DeleteSet {
  constructor () {
@@ -50,6 +47,25 @@ export class DeleteSet {
  }
 }

+/**
+ * Iterate over all structs that the DeleteSet gc's.
+ *
+ * @param {Transaction} transaction
+ * @param {DeleteSet} ds
+ * @param {StructStore} store
+ * @param {function(GC|Item):void} f
+ *
+ * @function
+ */
+export const iterateDeletedStructs = (transaction, ds, store, f) =>
+  ds.clients.forEach((deletes, clientid) => {
+    const structs = /** @type {Array<GC|Item>} */ (store.clients.get(clientid))
+    for (let i = 0; i < deletes.length; i++) {
+      const del = deletes[i]
+      iterateStructs(transaction, structs, del.clock, del.len, f)
+    }
+  })
+
 /**
 * @param {Array<DeleteItem>} dis
 * @param {number} clock
@@ -120,6 +136,27 @@ export const sortAndMergeDeleteSet = ds => {
  })
 }

+/**
+ * @param {DeleteSet} ds1
+ * @param {DeleteSet} ds2
+ * @return {DeleteSet} A fresh DeleteSet
+ */
+export const mergeDeleteSets = (ds1, ds2) => {
+  const merged = new DeleteSet()
+  // Write all keys from ds1 to merged. If ds2 has the same key, combine the sets.
+  ds1.clients.forEach((dels1, client) =>
+    merged.clients.set(client, dels1.concat(ds2.clients.get(client) || []))
+  )
+  // Write all missing keys from ds2 to merged.
+  ds2.clients.forEach((dels2, client) => {
+    if (!merged.clients.has(client)) {
+      merged.clients.set(client, dels2)
+    }
+  })
+  sortAndMergeDeleteSet(merged)
+  return merged
+}
+
 /**
 * @param {DeleteSet} ds
 * @param {ID} id
@@ -213,13 +250,13 @@ export const readDeleteSet = (decoder, transaction, store) => {
        let index = findIndexSS(structs, clock)
        /**
         * We can ignore the case of GC and Delete structs, because we are going to skip them
-         * @type {AbstractItem}
+         * @type {Item}
         */
        // @ts-ignore
        let struct = structs[index]
        // split the first item if necessary
        if (!struct.deleted && struct.id.clock < clock) {
-          structs.splice(index + 1, 0, struct.splitAt(transaction, clock - struct.id.clock))
+          structs.splice(index + 1, 0, splitItem(transaction, struct, clock - struct.id.clock))
          index++ // increase we now want to use the next struct
        }
        while (index < structs.length) {
@@ -228,7 +265,7 @@ export const readDeleteSet = (decoder, transaction, store) => {
          if (struct.id.clock < clock + len) {
            if (!struct.deleted) {
              if (clock + len < struct.id.clock + struct.length) {
-                structs.splice(index, 0, struct.splitAt(transaction, clock + len - struct.id.clock))
+                structs.splice(index, 0, splitItem(transaction, struct, clock + len - struct.id.clock))
              }
              struct.delete(transaction)
            }
@@ -244,6 +281,6 @@ export const readDeleteSet = (decoder, transaction, store) => {
  if (unappliedDS.clients.size > 0) {
    const unappliedDSEncoder = encoding.createEncoder()
    writeDeleteSet(unappliedDSEncoder, unappliedDS)
-    store.pendingDeleteReaders.push(decoding.createDecoder(encoding.toBuffer(unappliedDSEncoder)))
+    store.pendingDeleteReaders.push(decoding.createDecoder(encoding.toUint8Array(unappliedDSEncoder)))
  }
 }
--- a/src/utils/Doc.js
+++ b/src/utils/Doc.js
@@ -10,7 +10,7 @@ import {
  YMap,
  YXmlFragment,
  transact,
-  Transaction, YEvent // eslint-disable-line
+  Item, Transaction, YEvent // eslint-disable-line
 } from '../internals.js'

 import { Observable } from 'lib0/observable.js'
@@ -21,13 +21,13 @@ import * as map from 'lib0/map.js'
 * A Yjs instance handles the state of shared data.
 * @extends Observable<string>
 */
-export class Y extends Observable {
+export class Doc extends Observable {
  /**
   * @param {Object|undefined} conf configuration
   */
  constructor (conf = {}) {
    super()
-    // todo: change to clientId
+    this.gc = conf.gc || true
    this.clientID = random.uint32()
    /**
     * @type {Map<string, AbstractType<YEvent>>}
@@ -39,6 +39,11 @@ export class Y extends Observable {
     * @private
     */
    this._transaction = null
+    /**
+     * @type {Array<Transaction>}
+     * @private
+     */
+    this._transactionCleanups = []
  }
  /**
   * Changes that happen inside of a transaction are bundled. This means that
@@ -47,11 +52,12 @@ export class Y extends Observable {
   * other peers.
   *
   * @param {function(Transaction):void} f The function that should be executed as a transaction
+   * @param {any} [origin] Origin of who started the transaction. Will be stored on transaction.origin
   *
   * @public
   */
-  transact (f) {
-    transact(this, f)
+  transact (f, origin = null) {
+    transact(this, f, origin)
  }
  /**
   * Define a shared data type.
@@ -74,7 +80,7 @@ export class Y extends Observable {
   *   }
   *
   * @param {string} name
-   * @param {Function} TypeConstructor The constructor of the type definition
+   * @param {Function} TypeConstructor The constructor of the type definition. E.g. Y.Text, Y.Array, Y.Map, ...
   * @return {AbstractType<any>} The created type. Constructed with TypeConstructor
   *
   * @public
@@ -89,9 +95,18 @@ export class Y extends Observable {
    const Constr = type.constructor
    if (TypeConstructor !== AbstractType && Constr !== TypeConstructor) {
      if (Constr === AbstractType) {
-        const t = new Constr()
+        // @ts-ignore
+        const t = new TypeConstructor()
        t._map = type._map
+        type._map.forEach(/** @param {Item?} n */ n => {
+          for (; n !== null; n = n.left) {
+            n.parent = t
+          }
+        })
        t._start = type._start
+        for (let n = t._start; n !== null; n = n.right) {
+          n.parent = t
+        }
        t._length = type._length
        this.share.set(name, t)
        t._integrate(this, null)
--- a/src/utils/ID.js
+++ b/src/utils/ID.js
@@ -1,5 +1,5 @@

-import { AbstractType } from '../internals' // eslint-disable-line
+import { AbstractType } from '../internals.js' // eslint-disable-line

 import * as decoding from 'lib0/decoding.js'
 import * as encoding from 'lib0/encoding.js'
@@ -22,16 +22,6 @@ export class ID {
     */
    this.clock = clock
  }
-  /**
-   * @deprecated
-   * @todo remove and adapt relative position implementation
-   */
-  toJSON () {
-    return {
-      client: this.client,
-      clock: this.clock
-    }
-  }
 }

 /**
@@ -91,7 +81,7 @@ export const readID = decoder =>
 */
 export const findRootTypeKey = type => {
  // @ts-ignore _y must be defined, otherwise unexpected case
-  for (let [key, value] of type._y.share) {
+  for (let [key, value] of type.doc.share) {
    if (value === type) {
      return key
    }
--- a/src/utils/RelativePosition.js
+++ b/src/utils/RelativePosition.js
@@ -0,0 +1,272 @@
+
+import {
+  createID,
+  writeID,
+  readID,
+  compareIDs,
+  getState,
+  findRootTypeKey,
+  Item,
+  ContentType,
+  followRedone,
+  ID, Doc, AbstractType // eslint-disable-line
+} from '../internals.js'
+
+import * as encoding from 'lib0/encoding.js'
+import * as decoding from 'lib0/decoding.js'
+import * as error from 'lib0/error.js'
+
+/**
+ * A relative position is based on the Yjs model and is not affected by document changes.
+ * E.g. If you place a relative position before a certain character, it will always point to this character.
+ * If you place a relative position at the end of a type, it will always point to the end of the type.
+ *
+ * A numeric position is often unsuited for user selections, because it does not change when content is inserted
+ * before or after.
+ *
+ * ```Insert(0, 'x')('a|bc') = 'xa|bc'``` Where | is the relative position.
+ *
+ * One of the properties must be defined.
+ *
+ * @example
+ *   // Current cursor position is at position 10
+ *   const relativePosition = createRelativePositionFromIndex(yText, 10)
+ *   // modify yText
+ *   yText.insert(0, 'abc')
+ *   yText.delete(3, 10)
+ *   // Compute the cursor position
+ *   const absolutePosition = createAbsolutePositionFromRelativePosition(y, relativePosition)
+ *   absolutePosition.type === yText // => true
+ *   console.log('cursor location is ' + absolutePosition.index) // => cursor location is 3
+ *
+ */
+export class RelativePosition {
+  /**
+   * @param {ID|null} type
+   * @param {string|null} tname
+   * @param {ID|null} item
+   */
+  constructor (type, tname, item) {
+    /**
+     * @type {ID|null}
+     */
+    this.type = type
+    /**
+     * @type {string|null}
+     */
+    this.tname = tname
+    /**
+     * @type {ID | null}
+     */
+    this.item = item
+  }
+}
+
+/**
+ * @param {Object} json
+ * @return {RelativePosition}
+ *
+ * @function
+ */
+export const createRelativePositionFromJSON = json => new RelativePosition(json.type == null ? null : createID(json.type.client, json.type.clock), json.tname || null, json.item == null ? null : createID(json.item.client, json.item.clock))
+
+export class AbsolutePosition {
+  /**
+   * @param {AbstractType<any>} type
+   * @param {number} index
+   */
+  constructor (type, index) {
+    /**
+     * @type {AbstractType<any>}
+     */
+    this.type = type
+    /**
+     * @type {number}
+     */
+    this.index = index
+  }
+}
+
+/**
+ * @param {AbstractType<any>} type
+ * @param {number} index
+ *
+ * @function
+ */
+export const createAbsolutePosition = (type, index) => new AbsolutePosition(type, index)
+
+/**
+ * @param {AbstractType<any>} type
+ * @param {ID|null} item
+ *
+ * @function
+ */
+export const createRelativePosition = (type, item) => {
+  let typeid = null
+  let tname = null
+  if (type._item === null) {
+    tname = findRootTypeKey(type)
+  } else {
+    typeid = type._item.id
+  }
+  return new RelativePosition(typeid, tname, item)
+}
+
+/**
+ * Create a relativePosition based on a absolute position.
+ *
+ * @param {AbstractType<any>} type The base type (e.g. YText or YArray).
+ * @param {number} index The absolute position.
+ * @return {RelativePosition}
+ *
+ * @function
+ */
+export const createRelativePositionFromTypeIndex = (type, index) => {
+  let t = type._start
+  while (t !== null) {
+    if (!t.deleted && t.countable) {
+      if (t.length > index) {
+        // case 1: found position somewhere in the linked list
+        return createRelativePosition(type, createID(t.id.client, t.id.clock + index))
+      }
+      index -= t.length
+    }
+    t = t.right
+  }
+  return createRelativePosition(type, null)
+}
+
+/**
+ * @param {encoding.Encoder} encoder
+ * @param {RelativePosition} rpos
+ *
+ * @function
+ */
+export const writeRelativePosition = (encoder, rpos) => {
+  const { type, tname, item } = rpos
+  if (item !== null) {
+    encoding.writeVarUint(encoder, 0)
+    writeID(encoder, item)
+  } else if (tname !== null) {
+    // case 2: found position at the end of the list and type is stored in y.share
+    encoding.writeUint8(encoder, 1)
+    encoding.writeVarString(encoder, tname)
+  } else if (type !== null) {
+    // case 3: found position at the end of the list and type is attached to an item
+    encoding.writeUint8(encoder, 2)
+    writeID(encoder, type)
+  } else {
+    throw error.unexpectedCase()
+  }
+  return encoder
+}
+
+/**
+ * @param {RelativePosition} rpos
+ * @return {Uint8Array}
+ */
+export const encodeRelativePosition = rpos => {
+  const encoder = encoding.createEncoder()
+  writeRelativePosition(encoder, rpos)
+  return encoding.toUint8Array(encoder)
+}
+
+/**
+ * @param {decoding.Decoder} decoder
+ * @return {RelativePosition|null}
+ *
+ * @function
+ */
+export const readRelativePosition = decoder => {
+  let type = null
+  let tname = null
+  let itemID = null
+  switch (decoding.readVarUint(decoder)) {
+    case 0:
+      // case 1: found position somewhere in the linked list
+      itemID = readID(decoder)
+      break
+    case 1:
+      // case 2: found position at the end of the list and type is stored in y.share
+      tname = decoding.readVarString(decoder)
+      break
+    case 2: {
+      // case 3: found position at the end of the list and type is attached to an item
+      type = readID(decoder)
+    }
+  }
+  return new RelativePosition(type, tname, itemID)
+}
+
+/**
+ * @param {Uint8Array} uint8Array
+ * @return {RelativePosition|null}
+ */
+export const decodeRelativePosition = uint8Array => readRelativePosition(decoding.createDecoder(uint8Array))
+
+/**
+ * @param {RelativePosition} rpos
+ * @param {Doc} doc
+ * @return {AbsolutePosition|null}
+ *
+ * @function
+ */
+export const createAbsolutePositionFromRelativePosition = (rpos, doc) => {
+  const store = doc.store
+  const rightID = rpos.item
+  const typeID = rpos.type
+  const tname = rpos.tname
+  let type = null
+  let index = 0
+  if (rightID !== null) {
+    if (getState(store, rightID.client) <= rightID.clock) {
+      return null
+    }
+    const res = followRedone(store, rightID)
+    const right = res.item
+    if (!(right instanceof Item)) {
+      return null
+    }
+    type = right.parent
+    if (type._item !== null && !type._item.deleted) {
+      index = right.deleted || !right.countable ? 0 : res.diff
+      let n = right.left
+      while (n !== null) {
+        if (!n.deleted && n.countable) {
+          index += n.length
+        }
+        n = n.left
+      }
+    }
+  } else {
+    if (tname !== null) {
+      type = doc.get(tname)
+    } else if (typeID !== null) {
+      if (getState(store, typeID.client) <= typeID.clock) {
+        // type does not exist yet
+        return null
+      }
+      const { item } = followRedone(store, typeID)
+      if (item instanceof Item && item.content instanceof ContentType) {
+        type = item.content.type
+      } else {
+        // struct is garbage collected
+        return null
+      }
+    } else {
+      throw error.unexpectedCase()
+    }
+    index = type._length
+  }
+  return createAbsolutePosition(type, index)
+}
+
+/**
+ * @param {RelativePosition|null} a
+ * @param {RelativePosition|null} b
+ *
+ * @function
+ */
+export const compareRelativePositions = (a, b) => a === b || (
+  a !== null && b !== null && a.tname === b.tname && compareIDs(a.item, b.item) && compareIDs(a.type, b.type)
+)
--- a/src/utils/Snapshot.js
+++ b/src/utils/Snapshot.js
@@ -1,39 +1,37 @@

 import {
-  DeleteSet,
  isDeleted,
-  AbstractItem // eslint-disable-line
+  DeleteSet, Item // eslint-disable-line
 } from '../internals.js'

 export class Snapshot {
  /**
-   * @param {DeleteSet} ds delete store
+   * @param {DeleteSet} ds
   * @param {Map<number,number>} sm state map
-   * @param {Map<number,string>} userMap
-   * @private
   */
-  constructor (ds, sm, userMap) {
+  constructor (ds, sm) {
    /**
     * @type {DeleteSet}
     * @private
     */
-    this.ds = new DeleteSet()
+    this.ds = ds
    /**
     * State Map
     * @type {Map<number,number>}
     * @private
     */
    this.sm = sm
-    /**
-     * @type {Map<number,string>}
-     * @private
-     */
-    this.userMap = userMap
  }
 }

 /**
- * @param {AbstractItem} item
+ * @param {DeleteSet} ds
+ * @param {Map<number,number>} sm
+ */
+export const createSnapshot = (ds, sm) => new Snapshot(ds, sm)
+
+/**
+ * @param {Item} item
 * @param {Snapshot|undefined} snapshot
 *
 * @protected
--- a/src/utils/StructStore.js
+++ b/src/utils/StructStore.js
@@ -1,18 +1,18 @@

 import {
  GC,
-  Transaction, AbstractStructRef, ID, ItemType, AbstractItem, AbstractStruct // eslint-disable-line
+  splitItem,
+  GCRef, ItemRef, Transaction, ID, Item // eslint-disable-line
 } from '../internals.js'

 import * as math from 'lib0/math.js'
 import * as error from 'lib0/error.js'
-import * as encoding from 'lib0/encoding.js'
-import * as decoding from 'lib0/decoding.js'
+import * as decoding from 'lib0/decoding.js' // eslint-disable-line

 export class StructStore {
  constructor () {
    /**
-     * @type {Map<number,Array<AbstractStruct>>}
+     * @type {Map<number,Array<GC|Item>>}
     * @private
     */
    this.clients = new Map()
@@ -22,14 +22,14 @@ export class StructStore {
     * We could shift the array of refs instead, but shift is incredible
     * slow in Chrome for arrays with more than 100k elements
     * @see tryResumePendingStructRefs
-     * @type {Map<number,{i:number,refs:Array<AbstractStructRef>}>}
+     * @type {Map<number,{i:number,refs:Array<GCRef|ItemRef>}>}
     * @private
     */
    this.pendingClientsStructRefs = new Map()
    /**
     * Stack of pending structs waiting for struct dependencies
     * Maximum length of stack is structReaders.size
-     * @type {Array<AbstractStructRef>}
+     * @type {Array<GCRef|ItemRef>}
     * @private
     */
    this.pendingStack = []
@@ -51,7 +51,7 @@ export class StructStore {
 * @public
 * @function
 */
-export const getStates = store => {
+export const getStateVector = store => {
  const sm = new Map()
  store.clients.forEach((structs, client) => {
    const struct = structs[structs.length - 1]
@@ -97,7 +97,7 @@ export const integretyCheck = store => {

 /**
 * @param {StructStore} store
- * @param {AbstractStruct} struct
+ * @param {GC|Item} struct
 *
 * @private
 * @function
@@ -151,14 +151,14 @@ export const findIndexSS = (structs, clock) => {
 *
 * @param {StructStore} store
 * @param {ID} id
- * @return {AbstractStruct}
+ * @return {GC|Item}
 *
 * @private
 * @function
 */
 export const find = (store, id) => {
  /**
-   * @type {Array<AbstractStruct>}
+   * @type {Array<GC|Item>}
   */
  // @ts-ignore
  const structs = store.clients.get(id.client)
@@ -170,7 +170,7 @@ export const find = (store, id) => {
 *
 * @param {StructStore} store
 * @param {ID} id
- * @return {AbstractItem}
+ * @return {Item}
 *
 * @private
 * @function
@@ -179,45 +179,18 @@ export const find = (store, id) => {
 export const getItem = (store, id) => find(store, id)

 /**
- * Expects that id is actually in store. This function throws or is an infinite loop otherwise.
- *
- * @param {StructStore} store
- * @param {ID} id
- * @return {ItemType}
- *
- * @private
- * @function
- */
-// @ts-ignore
-export const getItemType = (store, id) => find(store, id)
-
-/**
- * Expects that id is actually in store. This function throws or is an infinite loop otherwise.
- *
 * @param {Transaction} transaction
- * @param {StructStore} store
- * @param {ID} id
- * @return {AbstractItem}
- *
- * @private
- * @function
+ * @param {Array<Item|GC>} structs
+ * @param {number} clock
 */
-export const getItemCleanStart = (transaction, store, id) => {
-  /**
-   * @type {Array<AbstractItem>}
-   */
-  // @ts-ignore
-  const structs = store.clients.get(id.client)
-  const index = findIndexSS(structs, id.clock)
-  /**
-   * @type {AbstractItem}
-   */
+export const findIndexCleanStart = (transaction, structs, clock) => {
+  const index = findIndexSS(structs, clock)
  let struct = structs[index]
-  if (struct.id.clock < id.clock && struct.constructor !== GC) {
-    struct = struct.splitAt(transaction, id.clock - struct.id.clock)
-    structs.splice(index + 1, 0, struct)
+  if (struct.id.clock < clock && struct instanceof Item) {
+    structs.splice(index + 1, 0, splitItem(transaction, struct, clock - struct.id.clock))
+    return index + 1
  }
-  return struct
+  return index
 }

 /**
@@ -226,21 +199,37 @@ export const getItemCleanStart = (transaction, store, id) => {
 * @param {Transaction} transaction
 * @param {StructStore} store
 * @param {ID} id
- * @return {AbstractItem}
+ * @return {Item}
+ *
+ * @private
+ * @function
+ */
+export const getItemCleanStart = (transaction, store, id) => {
+  const structs = /** @type {Array<GC|Item>} */ (store.clients.get(id.client))
+  return /** @type {Item} */ (structs[findIndexCleanStart(transaction, structs, id.clock)])
+}
+
+/**
+ * Expects that id is actually in store. This function throws or is an infinite loop otherwise.
+ *
+ * @param {Transaction} transaction
+ * @param {StructStore} store
+ * @param {ID} id
+ * @return {Item}
 *
 * @private
 * @function
 */
 export const getItemCleanEnd = (transaction, store, id) => {
  /**
-   * @type {Array<AbstractItem>}
+   * @type {Array<Item>}
   */
  // @ts-ignore
  const structs = store.clients.get(id.client)
  const index = findIndexSS(structs, id.clock)
  const struct = structs[index]
  if (id.clock !== struct.id.clock + struct.length - 1 && struct.constructor !== GC) {
-    structs.splice(index + 1, 0, struct.splitAt(transaction, id.clock - struct.id.clock + 1))
+    structs.splice(index + 1, 0, splitItem(transaction, struct, id.clock - struct.id.clock + 1))
  }
  return struct
 }
@@ -248,56 +237,40 @@ export const getItemCleanEnd = (transaction, store, id) => {
 /**
 * Replace `item` with `newitem` in store
 * @param {StructStore} store
- * @param {AbstractStruct} struct
- * @param {AbstractStruct} newStruct
+ * @param {GC|Item} struct
+ * @param {GC|Item} newStruct
 *
 * @private
 * @function
 */
 export const replaceStruct = (store, struct, newStruct) => {
-  /**
-   * @type {Array<AbstractStruct>}
-   */
-  // @ts-ignore
-  const structs = store.clients.get(struct.id.client)
+  const structs = /** @type {Array<GC|Item>} */ (store.clients.get(struct.id.client))
  structs[findIndexSS(structs, struct.id.clock)] = newStruct
 }

 /**
- * Read StateMap from Decoder and return as Map
+ * Iterate over a range of structs
 *
- * @param {decoding.Decoder} decoder
- * @return {Map<number,number>}
+ * @param {Transaction} transaction
+ * @param {Array<Item|GC>} structs
+ * @param {number} clockStart Inclusive start
+ * @param {number} len
+ * @param {function(GC|Item):void} f
 *
- * @private
 * @function
 */
-export const readStatesAsMap = decoder => {
-  const ss = new Map()
-  const ssLength = decoding.readVarUint(decoder)
-  for (let i = 0; i < ssLength; i++) {
-    const client = decoding.readVarUint(decoder)
-    const clock = decoding.readVarUint(decoder)
-    ss.set(client, clock)
+export const iterateStructs = (transaction, structs, clockStart, len, f) => {
+  if (len === 0) {
+    return
  }
-  return ss
-}
-
-/**
- * Write StateMap to Encoder
- *
- * @param {encoding.Encoder} encoder
- * @param {StructStore} store
- *
- * @private
- * @function
- */
-export const writeStates = (encoder, store) => {
-  encoding.writeVarUint(encoder, store.clients.size)
-  store.clients.forEach((structs, client) => {
-    const id = structs[structs.length - 1].id
-    encoding.writeVarUint(encoder, id.client)
-    encoding.writeVarUint(encoder, id.clock)
-  })
-  return encoder
+  const clockEnd = clockStart + len
+  let index = findIndexCleanStart(transaction, structs, clockStart)
+  let struct
+  do {
+    struct = structs[index++]
+    if (clockEnd < struct.id.clock + struct.length) {
+      findIndexCleanStart(transaction, structs, clockEnd)
+    }
+    f(struct)
+  } while (index < structs.length && structs[index].id.clock < clockEnd)
 }
--- a/src/utils/Transaction.js
+++ b/src/utils/Transaction.js
@@ -6,17 +6,17 @@ import {
  writeDeleteSet,
  DeleteSet,
  sortAndMergeDeleteSet,
-  getStates,
+  getStateVector,
  findIndexSS,
  callEventHandlerListeners,
-  AbstractItem,
-  ItemDeleted,
-  ID, AbstractType, AbstractStruct, YEvent, Y // eslint-disable-line
+  Item,
+  ID, AbstractType, AbstractStruct, YEvent, Doc // eslint-disable-line
 } from '../internals.js'

 import * as encoding from 'lib0/encoding.js'
 import * as map from 'lib0/map.js'
 import * as math from 'lib0/math.js'
+import * as set from 'lib0/set.js'

 /**
 * A transaction is created for every change on the Yjs model. It is possible
@@ -44,14 +44,15 @@ import * as math from 'lib0/math.js'
 */
 export class Transaction {
  /**
-   * @param {Y} y
+   * @param {Doc} doc
+   * @param {any} origin
   */
-  constructor (y) {
+  constructor (doc, origin) {
    /**
     * The Yjs instance.
-     * @type {Y}
+     * @type {Doc}
     */
-    this.y = y
+    this.doc = doc
    /**
     * Describes the set of deleted items by ids
     * @type {DeleteSet}
@@ -61,7 +62,7 @@ export class Transaction {
     * Holds the state before the transaction started.
     * @type {Map<Number,Number>}
     */
-    this.beforeState = getStates(y.store)
+    this.beforeState = getStateVector(doc.store)
    /**
     * Holds the state after the transaction.
     * @type {Map<Number,Number>}
@@ -80,32 +81,30 @@ export class Transaction {
     * @type {Map<AbstractType<YEvent>,Array<YEvent>>}
     */
    this.changedParentTypes = new Map()
-    /**
-     * @type {encoding.Encoder|null}
-     * @private
-     */
-    this._updateMessage = null
    /**
     * @type {Set<ID>}
     * @private
     */
    this._mergeStructs = new Set()
+    /**
+     * @type {any}
+     */
+    this.origin = origin
  }
-  /**
-   * @type {encoding.Encoder|null}
-   * @public
-   */
-  get updateMessage () {
-    // only create if content was added in transaction (state or ds changed)
-    if (this._updateMessage === null && (this.deleteSet.clients.size > 0 || map.any(this.afterState, (clock, client) => this.beforeState.get(client) !== clock))) {
-      const encoder = encoding.createEncoder()
-      sortAndMergeDeleteSet(this.deleteSet)
-      writeStructsFromTransaction(encoder, this)
-      writeDeleteSet(encoder, this.deleteSet)
-      this._updateMessage = encoder
-    }
-    return this._updateMessage
+}
+
+/**
+ * @param {Transaction} transaction
+ */
+export const computeUpdateMessageFromTransaction = transaction => {
+  if (transaction.deleteSet.clients.size === 0 && !map.any(transaction.afterState, (clock, client) => transaction.beforeState.get(client) !== clock)) {
+    return null
  }
+  const encoder = encoding.createEncoder()
+  sortAndMergeDeleteSet(transaction.deleteSet)
+  writeStructsFromTransaction(encoder, transaction)
+  writeDeleteSet(encoder, transaction.deleteSet)
+  return encoder
 }

 /**
@@ -115,130 +114,178 @@ export class Transaction {
 * @function
 */
 export const nextID = transaction => {
-  const y = transaction.y
+  const y = transaction.doc
  return createID(y.clientID, getState(y.store, y.clientID))
 }

+/**
+ * If `type.parent` was added in current transaction, `type` technically
+ * did not change, it was just added and we should not fire events for `type`.
+ *
+ * @param {Transaction} transaction
+ * @param {AbstractType<YEvent>} type
+ * @param {string|null} parentSub
+ */
+export const addChangedTypeToTransaction = (transaction, type, parentSub) => {
+  const item = type._item
+  if (item === null || (item.id.clock < (transaction.beforeState.get(item.id.client) || 0) && !item.deleted)) {
+    map.setIfUndefined(transaction.changed, type, set.create).add(parentSub)
+  }
+}
+
 /**
 * Implements the functionality of `y.transact(()=>{..})`
 *
- * @param {Y} y
+ * @param {Doc} doc
 * @param {function(Transaction):void} f
+ * @param {any} [origin]
 *
 * @private
 * @function
 */
-export const transact = (y, f) => {
+export const transact = (doc, f, origin = null) => {
+  const transactionCleanups = doc._transactionCleanups
  let initialCall = false
-  if (y._transaction === null) {
+  if (doc._transaction === null) {
    initialCall = true
-    y._transaction = new Transaction(y)
-    y.emit('beforeTransaction', [y._transaction, y])
+    doc._transaction = new Transaction(doc, origin)
+    transactionCleanups.push(doc._transaction)
+    doc.emit('beforeTransaction', [doc._transaction, doc])
  }
-  const transaction = y._transaction
  try {
-    f(transaction)
+    f(doc._transaction)
  } finally {
-    if (initialCall) {
-      y._transaction = null
-      y.emit('beforeObserverCalls', [transaction, y])
-      // emit change events on changed types
-      transaction.changed.forEach((subs, itemtype) => {
-        itemtype._callObserver(transaction, subs)
-      })
-      transaction.changedParentTypes.forEach((events, type) => {
-        events = events
-          .filter(event =>
-            event.target._item === null || !event.target._item.deleted
-          )
-        events
-          .forEach(event => {
-            event.currentTarget = type
-          })
-        // we don't need to check for events.length
-        // because we know it has at least one element
-        callEventHandlerListeners(type._dEH, events, transaction)
-      })
-      // only call afterTransaction listeners if anything changed
-      transaction.afterState = getStates(transaction.y.store)
-      // when all changes & events are processed, emit afterTransaction event
-      // transaction cleanup
-      const store = transaction.y.store
-      const ds = transaction.deleteSet
-      // replace deleted items with ItemDeleted / GC
-      sortAndMergeDeleteSet(ds)
-      y.emit('afterTransaction', [transaction, y])
-      for (const [client, deleteItems] of ds.clients) {
+    if (initialCall && transactionCleanups[0] === doc._transaction) {
+      // The first transaction ended, now process observer calls.
+      // Observer call may create new transactions for which we need to call the observers and do cleanup.
+      // We don't want to nest these calls, so we execute these calls one after another
+      for (let i = 0; i < transactionCleanups.length; i++) {
+        const transaction = transactionCleanups[i]
+        const store = transaction.doc.store
+        const ds = transaction.deleteSet
+        sortAndMergeDeleteSet(ds)
+        transaction.afterState = getStateVector(transaction.doc.store)
+        doc._transaction = null
+        doc.emit('beforeObserverCalls', [transaction, doc])
+        // emit change events on changed types
+        transaction.changed.forEach((subs, itemtype) => {
+          if (itemtype._item === null || !itemtype._item.deleted) {
+            itemtype._callObserver(transaction, subs)
+          }
+        })
+        transaction.changedParentTypes.forEach((events, type) => {
+          // We need to think about the possibility that the user transforms the
+          // Y.Doc in the event.
+          if (type._item === null || !type._item.deleted) {
+            events = events
+              .filter(event =>
+                event.target._item === null || !event.target._item.deleted
+              )
+            events
+              .forEach(event => {
+                event.currentTarget = type
+              })
+            // We don't need to check for events.length
+            // because we know it has at least one element
+            callEventHandlerListeners(type._dEH, events, transaction)
+          }
+        })
+        doc.emit('afterTransaction', [transaction, doc])
        /**
-         * @type {Array<AbstractStruct>}
+         * @param {Array<AbstractStruct>} structs
+         * @param {number} pos
         */
-        // @ts-ignore
-        const structs = store.clients.get(client)
-        for (let di = 0; di < deleteItems.length; di++) {
-          const deleteItem = deleteItems[di]
-          for (let si = findIndexSS(structs, deleteItem.clock); si < structs.length; si++) {
-            const struct = structs[si]
-            if (deleteItem.clock + deleteItem.len <= struct.id.clock) {
-              break
-            }
-            if (struct.deleted && struct instanceof AbstractItem && (struct.constructor !== ItemDeleted || (struct.parent._item !== null && struct.parent._item.deleted))) {
-              // check if we can GC
-              struct.gc(transaction, store)
+        const tryToMergeWithLeft = (structs, pos) => {
+          const left = structs[pos - 1]
+          const right = structs[pos]
+          if (left.deleted === right.deleted && left.constructor === right.constructor) {
+            if (left.mergeWith(right)) {
+              structs.splice(pos, 1)
+              if (right instanceof Item && right.parentSub !== null && right.parent._map.get(right.parentSub) === right) {
+                right.parent._map.set(right.parentSub, /** @type {Item} */ (left))
+              }
            }
          }
        }
-      }
-      /**
-       * @param {Array<AbstractStruct>} structs
-       * @param {number} pos
-       */
-      const tryToMergeWithLeft = (structs, pos) => {
-        const left = structs[pos - 1]
-        const right = structs[pos]
-        if (left.deleted === right.deleted && left.constructor === right.constructor) {
-          if (left.mergeWith(right)) {
-            structs.splice(pos, 1)
-            if (right instanceof AbstractItem && right.parentSub !== null && right.parent._map.get(right.parentSub) === right) {
-              // @ts-ignore we already did a constructor check above
-              right.parent._map.set(right.parentSub, left)
+        // Replace deleted items with ItemDeleted / GC.
+        // This is where content is actually remove from the Yjs Doc.
+        if (doc.gc) {
+          for (const [client, deleteItems] of ds.clients) {
+            const structs = /** @type {Array<AbstractStruct>} */ (store.clients.get(client))
+            for (let di = deleteItems.length - 1; di >= 0; di--) {
+              const deleteItem = deleteItems[di]
+              const endDeleteItemClock = deleteItem.clock + deleteItem.len
+              for (
+                let si = findIndexSS(structs, deleteItem.clock), struct = structs[si];
+                si < structs.length && struct.id.clock < endDeleteItemClock;
+                struct = structs[++si]
+              ) {
+                const struct = structs[si]
+                if (deleteItem.clock + deleteItem.len <= struct.id.clock) {
+                  break
+                }
+                if (struct instanceof Item && struct.deleted && !struct.keep) {
+                  struct.gc(store, false)
+                }
+              }
            }
          }
        }
-      }
-      // on all affected store.clients props, try to merge
-      for (const [client, clock] of transaction.afterState) {
-        const beforeClock = transaction.beforeState.get(client) || 0
-        if (beforeClock !== clock) {
-          /**
-           * @type {Array<AbstractStruct>}
-           */
-          // @ts-ignore
-          const structs = store.clients.get(client)
-          // we iterate from right to left so we can safely remove entries
-          const firstChangePos = math.max(findIndexSS(structs, beforeClock), 1)
-          for (let i = structs.length - 1; i >= firstChangePos; i--) {
-            tryToMergeWithLeft(structs, i)
+        // try to merge deleted / gc'd items
+        // merge from right to left for better efficiecy and so we don't miss any merge targets
+        for (const [client, deleteItems] of ds.clients) {
+          const structs = /** @type {Array<AbstractStruct>} */ (store.clients.get(client))
+          for (let di = deleteItems.length - 1; di >= 0; di--) {
+            const deleteItem = deleteItems[di]
+            // start with merging the item next to the last deleted item
+            const mostRightIndexToCheck = math.min(structs.length - 1, 1 + findIndexSS(structs, deleteItem.clock + deleteItem.len - 1))
+            for (
+              let si = mostRightIndexToCheck, struct = structs[si];
+              si > 0 && struct.id.clock >= deleteItem.clock;
+              struct = structs[--si]
+            ) {
+              tryToMergeWithLeft(structs, si)
+            }
+          }
+        }
+
+        // on all affected store.clients props, try to merge
+        for (const [client, clock] of transaction.afterState) {
+          const beforeClock = transaction.beforeState.get(client) || 0
+          if (beforeClock !== clock) {
+            const structs = /** @type {Array<AbstractStruct>} */ (store.clients.get(client))
+            // we iterate from right to left so we can safely remove entries
+            const firstChangePos = math.max(findIndexSS(structs, beforeClock), 1)
+            for (let i = structs.length - 1; i >= firstChangePos; i--) {
+              tryToMergeWithLeft(structs, i)
+            }
+          }
+        }
+        // try to merge mergeStructs
+        // @todo: it makes more sense to transform mergeStructs to a DS, sort it, and merge from right to left
+        //        but at the moment DS does not handle duplicates
+        for (const mid of transaction._mergeStructs) {
+          const client = mid.client
+          const clock = mid.clock
+          const structs = /** @type {Array<AbstractStruct>} */ (store.clients.get(client))
+          const replacedStructPos = findIndexSS(structs, clock)
+          if (replacedStructPos + 1 < structs.length) {
+            tryToMergeWithLeft(structs, replacedStructPos + 1)
+          }
+          if (replacedStructPos > 0) {
+            tryToMergeWithLeft(structs, replacedStructPos)
+          }
+        }
+        // @todo Merge all the transactions into one and provide send the data as a single update message
+        doc.emit('afterTransactionCleanup', [transaction, doc])
+        if (doc._observers.has('update')) {
+          const updateMessage = computeUpdateMessageFromTransaction(transaction)
+          if (updateMessage !== null) {
+            doc.emit('update', [encoding.toUint8Array(updateMessage), transaction.origin, doc])
          }
        }
      }
-      // try to merge mergeStructs
-      for (const mid of transaction._mergeStructs) {
-        const client = mid.client
-        const clock = mid.clock
-        /**
-         * @type {Array<AbstractStruct>}
-         */
-        // @ts-ignore
-        const structs = store.clients.get(client)
-        const replacedStructPos = findIndexSS(structs, clock)
-        if (replacedStructPos + 1 < structs.length) {
-          tryToMergeWithLeft(structs, replacedStructPos + 1)
-        }
-        if (replacedStructPos > 0) {
-          tryToMergeWithLeft(structs, replacedStructPos)
-        }
-      }
-      y.emit('afterTransactionCleanup', [transaction, y])
+      doc._transactionCleanups = []
    }
  }
 }
--- a/src/utils/UndoManager.js
+++ b/src/utils/UndoManager.js
@@ -1,202 +1,245 @@
-// @ts-nocheck
-
 import {
+  mergeDeleteSets,
+  iterateDeletedStructs,
+  keepItem,
+  transact,
+  redoItem,
+  iterateStructs,
  isParentOf,
  createID,
-  transact
+  followRedone,
+  getItemCleanStart,
+  Transaction, Doc, Item, GC, DeleteSet, AbstractType // eslint-disable-line
 } from '../internals.js'

-/**
- * @private
- */
-class ReverseOperation {
-  constructor (y, transaction, bindingInfos) {
-    this.created = new Date()
-    const beforeState = transaction.beforeState
-    if (beforeState.has(y.userID)) {
-      this.toState = createID(y.userID, y.ss.getState(y.userID) - 1)
-      this.fromState = createID(y.userID, beforeState.get(y.userID))
-    } else {
-      this.toState = null
-      this.fromState = null
-    }
-    this.deletedStructs = new Set()
-    transaction.deletedStructs.forEach(struct => {
-      this.deletedStructs.add({
-        from: struct._id,
-        len: struct._length
-      })
-    })
-    /**
-     * Maps from binding to binding information (e.g. cursor information)
-     */
-    this.bindingInfos = bindingInfos
-  }
-}
+import * as time from 'lib0/time.js'
+import { Observable } from 'lib0/observable.js'

-/**
- * @private
- * @function
- */
-function applyReverseOperation (y, scope, reverseBuffer) {
-  let performedUndo = false
-  let undoOp = null
-  transact(y, () => {
-    while (!performedUndo && reverseBuffer.length > 0) {
-      undoOp = reverseBuffer.pop()
-      // make sure that it is possible to iterate {from}-{to}
-      if (undoOp.fromState !== null) {
-        y.os.getItemCleanStart(undoOp.fromState)
-        y.os.getItemCleanEnd(undoOp.toState)
-        y.os.iterate(undoOp.fromState, undoOp.toState, op => {
-          while (op._deleted && op._redone !== null) {
-            op = op._redone
-          }
-          if (op._deleted === false && isParentOf(scope, op)) {
-            performedUndo = true
-            op._delete(y)
-          }
-        })
-      }
-      const redoitems = new Set()
-      for (let del of undoOp.deletedStructs) {
-        const fromState = del.from
-        const toState = createID(fromState.user, fromState.clock + del.len - 1)
-        y.os.getItemCleanStart(fromState)
-        y.os.getItemCleanEnd(toState)
-        y.os.iterate(fromState, toState, op => {
-          if (
-            isParentOf(scope, op) &&
-            op._parent !== y &&
-            (
-              op._id.user !== y.userID ||
-              undoOp.fromState === null ||
-              op._id.clock < undoOp.fromState.clock ||
-              op._id.clock > undoOp.toState.clock
-            )
-          ) {
-            redoitems.add(op)
-          }
-        })
-      }
-      redoitems.forEach(op => {
-        const opUndone = op._redo(y, redoitems)
-        performedUndo = performedUndo || opUndone
-      })
-    }
-  })
-  if (performedUndo && undoOp !== null) {
-    // should be performed after the undo transaction
-    undoOp.bindingInfos.forEach((info, binding) => {
-      binding._restoreUndoStackInfo(info)
-    })
-  }
-  return performedUndo
-}
-
-/**
- * Saves a history of locally applied operations. The UndoManager handles the
- * undoing and redoing of locally created changes.
- *
- * @private
- * @function
- */
-export class UndoManager {
+class StackItem {
  /**
-   * @param {YType} scope The scope on which to listen for changes.
-   * @param {Object} options Optionally provided configuration.
+   * @param {DeleteSet} ds
+   * @param {number} start clock start of the local client
+   * @param {number} len
   */
-  constructor (scope, options = {}) {
-    this.options = options
-    this._bindings = new Set(options.bindings)
-    options.captureTimeout = options.captureTimeout == null ? 500 : options.captureTimeout
-    this._undoBuffer = []
-    this._redoBuffer = []
-    this._scope = scope
-    this._undoing = false
-    this._redoing = false
-    this._lastTransactionWasUndo = false
-    const y = scope._y
-    this.y = y
-    let bindingInfos
-    y.on('beforeTransaction', (y, transaction, remote) => {
-      if (!remote) {
-        // Store binding information before transaction is executed
-        // By restoring the binding information, we can make sure that the state
-        // before the transaction can be recovered
-        bindingInfos = new Map()
-        this._bindings.forEach(binding => {
-          bindingInfos.set(binding, binding._getUndoStackInfo())
-        })
-      }
-    })
-    y.on('afterTransaction', (y, transaction, remote) => {
-      if (!remote && transaction.changedParentTypes.has(scope)) {
-        let reverseOperation = new ReverseOperation(y, transaction, bindingInfos)
-        if (!this._undoing) {
-          let lastUndoOp = this._undoBuffer.length > 0 ? this._undoBuffer[this._undoBuffer.length - 1] : null
-          if (
-            this._redoing === false &&
-            this._lastTransactionWasUndo === false &&
-            lastUndoOp !== null &&
-            ((options.captureTimeout < 0) || (reverseOperation.created.getTime() - lastUndoOp.created.getTime()) <= options.captureTimeout)
-          ) {
-            lastUndoOp.created = reverseOperation.created
-            if (reverseOperation.toState !== null) {
-              lastUndoOp.toState = reverseOperation.toState
-              if (lastUndoOp.fromState === null) {
-                lastUndoOp.fromState = reverseOperation.fromState
-              }
+  constructor (ds, start, len) {
+    this.ds = ds
+    this.start = start
+    this.len = len
+    /**
+     * Use this to save and restore metadata like selection range
+     */
+    this.meta = new Map()
+  }
+}
+
+/**
+ * @param {UndoManager} undoManager
+ * @param {Array<StackItem>} stack
+ * @param {string} eventType
+ * @return {StackItem?}
+ */
+const popStackItem = (undoManager, stack, eventType) => {
+  /**
+   * Whether a change happened
+   * @type {StackItem?}
+   */
+  let result = null
+  const doc = undoManager.doc
+  const scope = undoManager.scope
+  transact(doc, transaction => {
+    while (stack.length > 0 && result === null) {
+      const store = doc.store
+      const stackItem = /** @type {StackItem} */ (stack.pop())
+      const itemsToRedo = new Set()
+      let performedChange = false
+      iterateDeletedStructs(transaction, stackItem.ds, store, struct => {
+        if (struct instanceof Item && scope.some(type => isParentOf(type, struct))) {
+          itemsToRedo.add(struct)
+        }
+      })
+      itemsToRedo.forEach(item => {
+        performedChange = redoItem(transaction, item, itemsToRedo) !== null || performedChange
+      })
+      const structs = /** @type {Array<GC|Item>} */ (store.clients.get(doc.clientID))
+      /**
+       * @type {Array<Item>}
+       */
+      const itemsToDelete = []
+      iterateStructs(transaction, structs, stackItem.start, stackItem.len, struct => {
+        if (struct instanceof Item && !struct.deleted && scope.some(type => isParentOf(type, /** @type {Item} */ (struct)))) {
+          if (struct.redone !== null) {
+            let { item, diff } = followRedone(store, struct.id)
+            if (diff > 0) {
+              item = getItemCleanStart(transaction, store, createID(item.id.client, item.id.clock + diff))
            }
-            reverseOperation.deletedStructs.forEach(lastUndoOp.deletedStructs.add, lastUndoOp.deletedStructs)
-          } else {
-            this._lastTransactionWasUndo = false
-            this._undoBuffer.push(reverseOperation)
+            if (item.length > stackItem.len) {
+              getItemCleanStart(transaction, store, createID(item.id.client, item.id.clock + stackItem.len))
+            }
+            struct = item
          }
-          if (!this._redoing) {
-            this._redoBuffer = []
-          }
-        } else {
-          this._lastTransactionWasUndo = true
-          this._redoBuffer.push(reverseOperation)
+          itemsToDelete.push(struct)
+        }
+      })
+      // We want to delete in reverse order so that children are deleted before
+      // parents, so we have more information available when items are filtered.
+      for (let i = itemsToDelete.length - 1; i >= 0; i--) {
+        const item = itemsToDelete[i]
+        if (undoManager.deleteFilter(item)) {
+          item.delete(transaction)
+          performedChange = true
        }
      }
+      result = stackItem
+      if (result != null) {
+        undoManager.emit('stack-item-popped', [{ stackItem: result, type: eventType }, undoManager])
+      }
+    }
+  }, undoManager)
+  return result
+}
+
+/**
+ * @typedef {Object} UndoManagerOptions
+ * @property {number} [UndoManagerOptions.captureTimeout=500]
+ * @property {function(Item):boolean} [UndoManagerOptions.deleteFilter=()=>true] Sometimes
+ * it is necessary to filter whan an Undo/Redo operation can delete. If this
+ * filter returns false, the type/item won't be deleted even it is in the
+ * undo/redo scope.
+ * @property {Set<any>} [UndoManagerOptions.trackedOrigins=new Set([null])]
+ */
+
+/**
+ * Fires 'stack-item-added' event when a stack item was added to either the undo- or
+ * the redo-stack. You may store additional stack information via the
+ * metadata property on `event.stackItem.metadata` (it is a `Map` of metadata properties).
+ * Fires 'stack-item-popped' event when a stack item was popped from either the
+ * undo- or the redo-stack. You may restore the saved stack information from `event.stackItem.metadata`.
+ *
+ * @extends {Observable<'stack-item-added'|'stack-item-popped'>}
+ */
+export class UndoManager extends Observable {
+  /**
+   * @param {AbstractType<any>|Array<AbstractType<any>>} typeScope Accepts either a single type, or an array of types
+   * @param {UndoManagerOptions} options
+   */
+  constructor (typeScope, { captureTimeout, deleteFilter = () => true, trackedOrigins = new Set([null]) } = {}) {
+    if (captureTimeout == null) {
+      captureTimeout = 500
+    }
+    super()
+    this.scope = typeScope instanceof Array ? typeScope : [typeScope]
+    this.deleteFilter = deleteFilter
+    trackedOrigins.add(this)
+    this.trackedOrigins = trackedOrigins
+    /**
+     * @type {Array<StackItem>}
+     */
+    this.undoStack = []
+    /**
+     * @type {Array<StackItem>}
+     */
+    this.redoStack = []
+    /**
+     * Whether the client is currently undoing (calling UndoManager.undo)
+     *
+     * @type {boolean}
+     */
+    this.undoing = false
+    this.redoing = false
+    this.doc = /** @type {Doc} */ (this.scope[0].doc)
+    this.lastChange = 0
+    this.doc.on('afterTransaction', /** @param {Transaction} transaction */ transaction => {
+      // Only track certain transactions
+      if (!this.scope.some(type => transaction.changedParentTypes.has(type)) || (!this.trackedOrigins.has(transaction.origin) && (!transaction.origin || !this.trackedOrigins.has(transaction.origin.constructor)))) {
+        return
+      }
+      const undoing = this.undoing
+      const redoing = this.redoing
+      const stack = undoing ? this.redoStack : this.undoStack
+      if (undoing) {
+        this.stopCapturing() // next undo should not be appended to last stack item
+      } else if (!redoing) {
+        // neither undoing nor redoing: delete redoStack
+        this.redoStack = []
+      }
+      const beforeState = transaction.beforeState.get(this.doc.clientID) || 0
+      const afterState = transaction.afterState.get(this.doc.clientID) || 0
+      const now = time.getUnixTime()
+      if (now - this.lastChange < captureTimeout && stack.length > 0 && !undoing && !redoing) {
+        // append change to last stack op
+        const lastOp = stack[stack.length - 1]
+        lastOp.ds = mergeDeleteSets(lastOp.ds, transaction.deleteSet)
+        lastOp.len = afterState - lastOp.start
+      } else {
+        // create a new stack op
+        stack.push(new StackItem(transaction.deleteSet, beforeState, afterState - beforeState))
+      }
+      if (!undoing && !redoing) {
+        this.lastChange = now
+      }
+      // make sure that deleted structs are not gc'd
+      iterateDeletedStructs(transaction, transaction.deleteSet, transaction.doc.store, /** @param {Item|GC} item */ item => {
+        if (item instanceof Item && this.scope.some(type => isParentOf(type, item))) {
+          keepItem(item)
+        }
+      })
+      this.emit('stack-item-added', [{ stackItem: stack[stack.length - 1], origin: transaction.origin, type: undoing ? 'redo' : 'undo' }, this])
    })
  }

  /**
-   * Enforce that the next change is created as a separate item in the undo stack
+   * UndoManager merges Undo-StackItem if they are created within time-gap
+   * smaller than `options.captureTimeout`. Call `um.stopCapturing()` so that the next
+   * StackItem won't be merged.
+   *
+   *
+   * @example
+   *     // without stopCapturing
+   *     ytext.insert(0, 'a')
+   *     ytext.insert(1, 'b')
+   *     um.undo()
+   *     ytext.toString() // => '' (note that 'ab' was removed)
+   *     // with stopCapturing
+   *     ytext.insert(0, 'a')
+   *     um.stopCapturing()
+   *     ytext.insert(0, 'b')
+   *     um.undo()
+   *     ytext.toString() // => 'a' (note that only 'b' was removed)
   *
-   * @private
-   * @function
   */
-  flushChanges () {
-    this._lastTransactionWasUndo = true
+  stopCapturing () {
+    this.lastChange = 0
  }

  /**
-   * Undo the last locally created change.
+   * Undo last changes on type.
   *
-   * @private
-   * @function
+   * @return {StackItem?} Returns StackItem if a change was applied
   */
  undo () {
-    this._undoing = true
-    const performedUndo = applyReverseOperation(this.y, this._scope, this._undoBuffer)
-    this._undoing = false
-    return performedUndo
+    this.undoing = true
+    let res
+    try {
+      res = popStackItem(this, this.undoStack, 'undo')
+    } finally {
+      this.undoing = false
+    }
+    return res
  }

  /**
-   * Redo the last locally created change.
+   * Redo last undo operation.
   *
-   * @private
-   * @function
+   * @return {StackItem?} Returns StackItem if a change was applied
   */
  redo () {
-    this._redoing = true
-    const performedRedo = applyReverseOperation(this.y, this._scope, this._redoBuffer)
-    this._redoing = false
-    return performedRedo
+    this.redoing = true
+    let res
+    try {
+      res = popStackItem(this, this.redoStack, 'redo')
+    } finally {
+      this.redoing = false
+    }
+    return res
  }
 }
--- a/src/utils/cursor.js
+++ b/src/utils/cursor.js
@@ -1,266 +0,0 @@
-/**
- * @module Cursors
- */
-
-import {
-  getItem,
-  getItemType,
-  createID,
-  writeID,
-  readID,
-  compareIDs,
-  getState,
-  findRootTypeKey,
-  AbstractItem,
-  ID, StructStore, Y, AbstractType // eslint-disable-line
-} from '../internals.js'
-
-import * as encoding from 'lib0/encoding.js'
-import * as decoding from 'lib0/decoding.js'
-import * as error from 'lib0/error.js'
-
-/**
- * A Cursor is a relative position that is based on the Yjs model. In contrast to an
- * absolute position (position by index), the Cursor can be
- * recomputed when remote changes are received. For example:
- *
- * ```Insert(0, 'x')('a|bc') = 'xa|bc'``` Where | is the cursor position.
- *
- * A relative cursor position can be obtained with the function
- *
- * One of the properties must be defined.
- *
- * @example
- *   // Current cursor position is at position 10
- *   const relativePosition = createCursorFromOffset(yText, 10)
- *   // modify yText
- *   yText.insert(0, 'abc')
- *   yText.delete(3, 10)
- *   // Compute the cursor position
- *   const absolutePosition = toAbsolutePosition(y, relativePosition)
- *   absolutePosition.type === yText // => true
- *   console.log('cursor location is ' + absolutePosition.offset) // => cursor location is 3
- *
- */
-export class Cursor {
-  /**
-   * @param {ID|null} type
-   * @param {string|null} tname
-   * @param {ID|null} item
-   */
-  constructor (type, tname, item) {
-    /**
-     * @type {ID|null}
-     */
-    this.type = type
-    /**
-     * @type {string|null}
-     */
-    this.tname = tname
-    /**
-     * @type {ID | null}
-     */
-    this.item = item
-  }
-  toJSON () {
-    const json = {}
-    if (this.type !== null) {
-      json.type = this.type.toJSON()
-    }
-    if (this.tname !== null) {
-      json.tname = this.tname
-    }
-    if (this.item !== null) {
-      json.item = this.item.toJSON()
-    }
-    return json
-  }
-}
-
-/**
- * @param {Object} json
- * @return {Cursor}
- *
- * @function
- */
-export const createCursorFromJSON = json => new Cursor(json.type == null ? null : createID(json.type.client, json.type.clock), json.tname || null, json.item == null ? null : createID(json.item.client, json.item.clock))
-
-export class AbsolutePosition {
-  /**
-   * @param {AbstractType<any>} type
-   * @param {number} offset
-   */
-  constructor (type, offset) {
-    /**
-     * @type {AbstractType<any>}
-     */
-    this.type = type
-    /**
-     * @type {number}
-     */
-    this.offset = offset
-  }
-}
-
-/**
- * @param {AbstractType<any>} type
- * @param {number} offset
- *
- * @function
- */
-export const createAbsolutePosition = (type, offset) => new AbsolutePosition(type, offset)
-
-/**
- * @param {AbstractType<any>} type
- * @param {ID|null} item
- *
- * @function
- */
-export const createCursor = (type, item) => {
-  let typeid = null
-  let tname = null
-  if (type._item === null) {
-    tname = findRootTypeKey(type)
-  } else {
-    typeid = type._item.id
-  }
-  return new Cursor(typeid, tname, item)
-}
-
-/**
- * Create a relativePosition based on a absolute position.
- *
- * @param {AbstractType<any>} type The base type (e.g. YText or YArray).
- * @param {number} offset The absolute position.
- * @return {Cursor}
- *
- * @function
- */
-export const createCursorFromTypeOffset = (type, offset) => {
-  let t = type._start
-  while (t !== null) {
-    if (!t.deleted && t.countable) {
-      if (t.length > offset) {
-        // case 1: found position somewhere in the linked list
-        return createCursor(type, createID(t.id.client, t.id.clock + offset))
-      }
-      offset -= t.length
-    }
-    t = t.right
-  }
-  return createCursor(type, null)
-}
-
-/**
- * @param {encoding.Encoder} encoder
- * @param {Cursor} rpos
- *
- * @function
- */
-export const writeCursor = (encoder, rpos) => {
-  const { type, tname, item } = rpos
-  if (item !== null) {
-    encoding.writeVarUint(encoder, 0)
-    writeID(encoder, item)
-  } else if (tname !== null) {
-    // case 2: found position at the end of the list and type is stored in y.share
-    encoding.writeUint8(encoder, 1)
-    encoding.writeVarString(encoder, tname)
-  } else if (type !== null) {
-    // case 3: found position at the end of the list and type is attached to an item
-    encoding.writeUint8(encoder, 2)
-    writeID(encoder, type)
-  } else {
-    throw error.unexpectedCase()
-  }
-  return encoder
-}
-
-/**
- * @param {decoding.Decoder} decoder
- * @param {Y} y
- * @param {StructStore} store
- * @return {Cursor|null}
- *
- * @function
- */
-export const readCursor = (decoder, y, store) => {
-  let type = null
-  let tname = null
-  let itemID = null
-  switch (decoding.readVarUint(decoder)) {
-    case 0:
-      // case 1: found position somewhere in the linked list
-      itemID = readID(decoder)
-      break
-    case 1:
-      // case 2: found position at the end of the list and type is stored in y.share
-      tname = decoding.readVarString(decoder)
-      break
-    case 2: {
-      // case 3: found position at the end of the list and type is attached to an item
-      type = readID(decoder)
-    }
-  }
-  return new Cursor(type, tname, itemID)
-}
-
-/**
- * @param {Cursor} cursor
- * @param {Y} y
- * @return {AbsolutePosition|null}
- *
- * @function
- */
-export const createAbsolutePositionFromCursor = (cursor, y) => {
-  const store = y.store
-  const rightID = cursor.item
-  const typeID = cursor.type
-  const tname = cursor.tname
-  let type = null
-  let offset = 0
-  if (rightID !== null) {
-    if (getState(store, rightID.client) <= rightID.clock) {
-      return null
-    }
-    const right = getItem(store, rightID)
-    if (!(right instanceof AbstractItem)) {
-      return null
-    }
-    offset = right.deleted || !right.countable ? 0 : rightID.clock - right.id.clock
-    let n = right.left
-    while (n !== null) {
-      if (!n.deleted && n.countable) {
-        offset += n.length
-      }
-      n = n.left
-    }
-    type = right.parent
-  } else {
-    if (tname !== null) {
-      type = y.get(tname)
-    } else if (typeID !== null) {
-      type = getItemType(store, typeID).type
-    } else {
-      throw error.unexpectedCase()
-    }
-    offset = type._length
-  }
-  if (type._item !== null && type._item.deleted) {
-    return null
-  }
-  return createAbsolutePosition(type, offset)
-}
-
-/**
- * @param {Cursor|null} a
- * @param {Cursor|null} b
- *
- * @function
- */
-export const compareCursors = (a, b) => a === b || (
-  a !== null && b !== null && a.tname === b.tname && (
-    (a.item !== null && b.item !== null && compareIDs(a.item, b.item)) ||
-    (a.type !== null && b.type !== null && compareIDs(a.type, b.type))
-  )
-)
--- a/src/utils/encoding.js
+++ b/src/utils/encoding.js
@@ -1,47 +1,38 @@

 /**
 * @module encoding
+ *
+ * We use the first five bits in the info flag for determining the type of the struct.
+ *
+ * 0: GC
+ * 1: Item with Deleted content
+ * 2: Item with JSON content
+ * 3: Item with Binary content
+ * 4: Item with String content
+ * 5: Item with Embed content (for richtext content)
+ * 6: Item with Format content (a formatting marker for richtext content)
+ * 7: Item with Type
 */

 import {
  findIndexSS,
  GCRef,
-  ItemBinaryRef,
-  ItemDeletedRef,
-  ItemEmbedRef,
-  ItemFormatRef,
-  ItemJSONRef,
-  ItemStringRef,
-  ItemTypeRef,
+  ItemRef,
  writeID,
  createID,
  readID,
  getState,
-  getStates,
+  getStateVector,
  readDeleteSet,
  writeDeleteSet,
  createDeleteSetFromStructStore,
-  Transaction, AbstractStruct, AbstractStructRef, StructStore, ID // eslint-disable-line
+  Doc, Transaction, AbstractStruct, StructStore, ID // eslint-disable-line
 } from '../internals.js'

 import * as encoding from 'lib0/encoding.js'
 import * as decoding from 'lib0/decoding.js'
 import * as binary from 'lib0/binary.js'

-/**
- * @private
- */
-export const structRefs = [
-  GCRef,
-  ItemBinaryRef,
-  ItemDeletedRef,
-  ItemEmbedRef,
-  ItemFormatRef,
-  ItemJSONRef,
-  ItemStringRef,
-  ItemTypeRef
-]
-
 /**
 * @param {encoding.Encoder} encoder
 * @param {Array<AbstractStruct>} structs All structs by `client`
@@ -68,19 +59,19 @@ const writeStructs = (encoder, structs, client, clock) => {
 * @param {decoding.Decoder} decoder
 * @param {number} numOfStructs
 * @param {ID} nextID
- * @return {Array<AbstractStructRef>}
+ * @return {Array<GCRef|ItemRef>}
 *
 * @private
 * @function
 */
 const readStructRefs = (decoder, numOfStructs, nextID) => {
  /**
-   * @type {Array<AbstractStructRef>}
+   * @type {Array<GCRef|ItemRef>}
   */
  const refs = []
  for (let i = 0; i < numOfStructs; i++) {
    const info = decoding.readUint8(decoder)
-    const ref = new structRefs[binary.BITS5 & info](decoder, nextID, info)
+    const ref = (binary.BITS5 & info) === 0 ? new GCRef(decoder, nextID, info) : new ItemRef(decoder, nextID, info)
    nextID = createID(nextID.client, nextID.clock + ref.length)
    refs.push(ref)
  }
@@ -104,7 +95,7 @@ export const writeClientsStructs = (encoder, store, _sm) => {
      sm.set(client, clock)
    }
  })
-  getStates(store).forEach((clock, client) => {
+  getStateVector(store).forEach((clock, client) => {
    if (!_sm.has(client)) {
      sm.set(client, 0)
    }
@@ -119,14 +110,14 @@ export const writeClientsStructs = (encoder, store, _sm) => {

 /**
 * @param {decoding.Decoder} decoder The decoder object to read data from.
- * @return {Map<number,Array<AbstractStructRef>>}
+ * @return {Map<number,Array<GCRef|ItemRef>>}
 *
 * @private
 * @function
 */
 export const readClientsStructRefs = decoder => {
  /**
-   * @type {Map<number,Array<AbstractStructRef>>}
+   * @type {Map<number,Array<GCRef|ItemRef>>}
   */
  const clientRefs = new Map()
  const numOfStateUpdates = decoding.readVarUint(decoder)
@@ -193,7 +184,7 @@ const resumeStructIntegration = (transaction, store) => {
          structRefs.refs[structRefs.i] = ref
          stack[stack.length - 1] = r
          // sort the set because this approach might bring the list out of order
-          structRefs.refs = structRefs.refs.slice(structRefs.i).sort((r1, r2) => r1.id.client - r2.id.client)
+          structRefs.refs = structRefs.refs.slice(structRefs.i).sort((r1, r2) => r1.id.clock - r2.id.clock)
          structRefs.i = 0
          continue
        }
@@ -250,11 +241,11 @@ export const tryResumePendingDeleteReaders = (transaction, store) => {
 * @private
 * @function
 */
-export const writeStructsFromTransaction = (encoder, transaction) => writeClientsStructs(encoder, transaction.y.store, transaction.beforeState)
+export const writeStructsFromTransaction = (encoder, transaction) => writeClientsStructs(encoder, transaction.doc.store, transaction.beforeState)

 /**
 * @param {StructStore} store
- * @param {Map<number, Array<AbstractStructRef>>} clientsStructsRefs
+ * @param {Map<number, Array<GCRef|ItemRef>>} clientsStructsRefs
 *
 * @private
 * @function
@@ -297,25 +288,128 @@ export const readStructs = (decoder, transaction, store) => {
 }

 /**
+ * Read and apply a document update.
+ *
+ * This function has the same effect as `applyUpdate` but accepts an decoder.
+ *
 * @param {decoding.Decoder} decoder
- * @param {Transaction} transaction
- * @param {StructStore} store
+ * @param {Doc} ydoc
+ * @param {any} [transactionOrigin] This will be stored on `transaction.origin` and `.on('update', (update, origin))`
 *
 * @function
 */
-export const readModel = (decoder, transaction, store) => {
-  readStructs(decoder, transaction, store)
-  readDeleteSet(decoder, transaction, store)
+export const readUpdate = (decoder, ydoc, transactionOrigin) =>
+  ydoc.transact(transaction => {
+    readStructs(decoder, transaction, ydoc.store)
+    readDeleteSet(decoder, transaction, ydoc.store)
+  }, transactionOrigin)
+
+/**
+ * Apply a document update created by, for example, `y.on('update', update => ..)` or `update = encodeStateAsUpdate()`.
+ *
+ * This function has the same effect as `readUpdate` but accepts an Uint8Array instead of a Decoder.
+ *
+ * @param {Doc} ydoc
+ * @param {Uint8Array} update
+ * @param {any} [transactionOrigin] This will be stored on `transaction.origin` and `.on('update', (update, origin))`
+ *
+ * @function
+ */
+export const applyUpdate = (ydoc, update, transactionOrigin) =>
+  readUpdate(decoding.createDecoder(update), ydoc, transactionOrigin)
+
+/**
+ * Write all the document as a single update message. If you specify the state of the remote client (`targetStateVector`) it will
+ * only write the operations that are missing.
+ *
+ * @param {encoding.Encoder} encoder
+ * @param {Doc} doc
+ * @param {Map<number,number>} [targetStateVector] The state of the target that receives the update. Leave empty to write all known structs
+ *
+ * @function
+ */
+export const writeStateAsUpdate = (encoder, doc, targetStateVector = new Map()) => {
+  writeClientsStructs(encoder, doc.store, targetStateVector)
+  writeDeleteSet(encoder, createDeleteSetFromStructStore(doc.store))
 }

 /**
- * @param {encoding.Encoder} encoder
- * @param {StructStore} store
- * @param {Map<number,number>} [targetState] The state of the target that receives the update. Leave empty to write all known structs
+ * Write all the document as a single update message that can be applied on the remote document. If you specify the state of the remote client (`targetState`) it will
+ * only write the operations that are missing.
+ *
+ * Use `writeStateAsUpdate` instead if you are working with lib0/encoding.js#Encoder
+ *
+ * @param {Doc} doc
+ * @param {Uint8Array} [encodedTargetStateVector] The state of the target that receives the update. Leave empty to write all known structs
+ * @return {Uint8Array}
 *
 * @function
 */
-export const writeModel = (encoder, store, targetState = new Map()) => {
-  writeClientsStructs(encoder, store, targetState)
-  writeDeleteSet(encoder, createDeleteSetFromStructStore(store))
+export const encodeStateAsUpdate = (doc, encodedTargetStateVector) => {
+  const encoder = encoding.createEncoder()
+  const targetStateVector = encodedTargetStateVector == null ? new Map() : decodeStateVector(encodedTargetStateVector)
+  writeStateAsUpdate(encoder, doc, targetStateVector)
+  return encoding.toUint8Array(encoder)
+}
+
+/**
+ * Read state vector from Decoder and return as Map
+ *
+ * @param {decoding.Decoder} decoder
+ * @return {Map<number,number>} Maps `client` to the number next expected `clock` from that client.
+ *
+ * @function
+ */
+export const readStateVector = decoder => {
+  const ss = new Map()
+  const ssLength = decoding.readVarUint(decoder)
+  for (let i = 0; i < ssLength; i++) {
+    const client = decoding.readVarUint(decoder)
+    const clock = decoding.readVarUint(decoder)
+    ss.set(client, clock)
+  }
+  return ss
+}
+
+/**
+ * Read decodedState and return State as Map.
+ *
+ * @param {Uint8Array} decodedState
+ * @return {Map<number,number>} Maps `client` to the number next expected `clock` from that client.
+ *
+ * @function
+ */
+export const decodeStateVector = decodedState => readStateVector(decoding.createDecoder(decodedState))
+
+/**
+ * Write State Vector to `lib0/encoding.js#Encoder`.
+ *
+ * @param {encoding.Encoder} encoder
+ * @param {Doc} doc
+ *
+ * @function
+ */
+export const writeDocumentStateVector = (encoder, doc) => {
+  encoding.writeVarUint(encoder, doc.store.clients.size)
+  doc.store.clients.forEach((structs, client) => {
+    const struct = structs[structs.length - 1]
+    const id = struct.id
+    encoding.writeVarUint(encoder, id.client)
+    encoding.writeVarUint(encoder, id.clock + struct.length)
+  })
+  return encoder
+}
+
+/**
+ * Encode State as Uint8Array.
+ *
+ * @param {Doc} doc
+ * @return {Uint8Array}
+ *
+ * @function
+ */
+export const encodeStateVector = doc => {
+  const encoder = encoding.createEncoder()
+  writeDocumentStateVector(encoder, doc)
+  return encoding.toUint8Array(encoder)
 }
--- a/src/utils/isParentOf.js
+++ b/src/utils/isParentOf.js
@@ -1,22 +1,22 @@

-import { AbstractType } from '../internals.js' // eslint-disable-line
+import { AbstractType, Item } from '../internals.js' // eslint-disable-line

 /**
 * Check if `parent` is a parent of `child`.
 *
 * @param {AbstractType<any>} parent
- * @param {AbstractType<any>} child
+ * @param {Item|null} child
 * @return {Boolean} Whether `parent` is a parent of `child`.
 *
 * @private
 * @function
 */
 export const isParentOf = (parent, child) => {
-  while (child._item !== null) {
-    if (child === parent) {
+  while (child !== null) {
+    if (child.parent === parent) {
      return true
    }
-    child = child._item.parent
+    child = child.parent._item
  }
  return false
 }
--- a/tests/encoding.tests.js
+++ b/tests/encoding.tests.js
@@ -1,36 +1,28 @@
 import * as t from 'lib0/testing.js'

 import {
-  structRefs,
-  structGCRefNumber,
-  structBinaryRefNumber,
-  structDeletedRefNumber,
-  structEmbedRefNumber,
-  structFormatRefNumber,
-  structJSONRefNumber,
-  structStringRefNumber,
-  structTypeRefNumber,
-  GCRef,
-  ItemBinaryRef,
-  ItemDeletedRef,
-  ItemEmbedRef,
-  ItemFormatRef,
-  ItemJSONRef,
-  ItemStringRef,
-  ItemTypeRef
+  contentRefs,
+  readContentBinary,
+  readContentDeleted,
+  readContentString,
+  readContentJSON,
+  readContentEmbed,
+  readContentType,
+  readContentFormat,
+  readContentAny
 } from '../src/internals.js'

 /**
 * @param {t.TestCase} tc
 */
 export const testStructReferences = tc => {
-  t.assert(structRefs.length === 8)
-  t.assert(structRefs[structGCRefNumber] === GCRef)
-  t.assert(structRefs[structBinaryRefNumber] === ItemBinaryRef)
-  t.assert(structRefs[structDeletedRefNumber] === ItemDeletedRef)
-  t.assert(structRefs[structEmbedRefNumber] === ItemEmbedRef)
-  t.assert(structRefs[structFormatRefNumber] === ItemFormatRef)
-  t.assert(structRefs[structJSONRefNumber] === ItemJSONRef)
-  t.assert(structRefs[structStringRefNumber] === ItemStringRef)
-  t.assert(structRefs[structTypeRefNumber] === ItemTypeRef)
+  t.assert(contentRefs.length === 9)
+  t.assert(contentRefs[1] === readContentDeleted)
+  t.assert(contentRefs[2] === readContentJSON) // TODO: deprecate content json?
+  t.assert(contentRefs[3] === readContentBinary)
+  t.assert(contentRefs[4] === readContentString)
+  t.assert(contentRefs[5] === readContentEmbed)
+  t.assert(contentRefs[6] === readContentFormat)
+  t.assert(contentRefs[7] === readContentType)
+  t.assert(contentRefs[8] === readContentAny)
 }
--- a/tests/index.js
+++ b/tests/index.js
@@ -4,6 +4,7 @@ import * as map from './y-map.tests.js'
 import * as text from './y-text.tests.js'
 import * as xml from './y-xml.tests.js'
 import * as encoding from './encoding.tests.js'
+import * as undoredo from './undo-redo.tests.js'

 import { runTests } from 'lib0/testing.js'
 import { isBrowser, isNode } from 'lib0/environment.js'
@@ -13,7 +14,7 @@ if (isBrowser) {
  log.createVConsole(document.body)
 }
 runTests({
-  map, array, text, xml, encoding
+  map, array, text, xml, encoding, undoredo
 }).then(success => {
  /* istanbul ignore next */
  if (isNode) {
--- a/tests/testHelper.js
+++ b/tests/testHelper.js
@@ -2,36 +2,21 @@ import * as Y from '../src/index.js'

 import {
  createDeleteSetFromStructStore,
-  getStates,
-  AbstractItem,
-  DeleteSet, StructStore // eslint-disable-line
+  getStateVector,
+  Item,
+  DeleteItem, DeleteSet, StructStore, Doc // eslint-disable-line
 } from '../src/internals.js'

 import * as t from 'lib0/testing.js'
 import * as prng from 'lib0/prng.js'
-import { createMutex } from 'lib0/mutex.js'
 import * as encoding from 'lib0/encoding.js'
 import * as decoding from 'lib0/decoding.js'
 import * as syncProtocol from 'y-protocols/sync.js'
-
-/**
- * @param {TestYInstance} y
- * @param {Y.Transaction} transaction
- */
-const afterTransaction = (y, transaction) => {
-  y.mMux(() => {
-    const m = transaction.updateMessage
-    if (m !== null) {
-      const encoder = encoding.createEncoder()
-      syncProtocol.writeUpdate(encoder, m)
-      broadcastMessage(y, encoding.toBuffer(encoder))
-    }
-  })
-}
+export * from '../src/internals.js'

 /**
 * @param {TestYInstance} y // publish message created by `y` to all other online clients
- * @param {ArrayBuffer} m
+ * @param {Uint8Array} m
 */
 const broadcastMessage = (y, m) => {
  if (y.tc.onlineConns.has(y)) {
@@ -43,7 +28,7 @@ const broadcastMessage = (y, m) => {
  }
 }

-export class TestYInstance extends Y.Y {
+export class TestYInstance extends Doc {
  /**
   * @param {TestConnector} testConnector
   * @param {number} clientID
@@ -56,17 +41,18 @@ export class TestYInstance extends Y.Y {
     */
    this.tc = testConnector
    /**
-     * @type {Map<TestYInstance, Array<ArrayBuffer>>}
+     * @type {Map<TestYInstance, Array<Uint8Array>>}
     */
    this.receiving = new Map()
-    /**
-     * Message mutex
-     * @type {Function}
-     */
-    this.mMux = createMutex()
    testConnector.allConns.add(this)
    // set up observe on local model
-    this.on('afterTransactionCleanup', afterTransaction)
+    this.on('update', /** @param {Uint8Array} update @param {any} origin */ (update, origin) => {
+      if (origin !== testConnector) {
+        const encoder = encoding.createEncoder()
+        syncProtocol.writeUpdate(encoder, update)
+        broadcastMessage(this, encoding.toUint8Array(encoder))
+      }
+    })
    this.connect()
  }
  /**
@@ -84,15 +70,15 @@ export class TestYInstance extends Y.Y {
    if (!this.tc.onlineConns.has(this)) {
      this.tc.onlineConns.add(this)
      const encoder = encoding.createEncoder()
-      syncProtocol.writeSyncStep1(encoder, this.store)
+      syncProtocol.writeSyncStep1(encoder, this)
      // publish SyncStep1
-      broadcastMessage(this, encoding.toBuffer(encoder))
+      broadcastMessage(this, encoding.toUint8Array(encoder))
      this.tc.onlineConns.forEach(remoteYInstance => {
        if (remoteYInstance !== this) {
          // remote instance sends instance to this instance
          const encoder = encoding.createEncoder()
-          syncProtocol.writeSyncStep1(encoder, remoteYInstance.store)
-          this._receive(encoding.toBuffer(encoder), remoteYInstance)
+          syncProtocol.writeSyncStep1(encoder, remoteYInstance)
+          this._receive(encoding.toUint8Array(encoder), remoteYInstance)
        }
      })
    }
@@ -101,7 +87,7 @@ export class TestYInstance extends Y.Y {
   * Receive a message from another client. This message is only appended to the list of receiving messages.
   * TestConnector decides when this client actually reads this message.
   *
-   * @param {ArrayBuffer} message
+   * @param {Uint8Array} message
   * @param {TestYInstance} remoteClient
   */
  _receive (message, remoteClient) {
@@ -165,14 +151,12 @@ export class TestConnector {
        return this.flushRandomMessage()
      }
      const encoder = encoding.createEncoder()
-      receiver.mMux(() => {
-        // console.log('receive (' + sender.userID + '->' + receiver.userID + '):\n', syncProtocol.stringifySyncMessage(decoding.createDecoder(m), receiver))
-        // do not publish data created when this function is executed (could be ss2 or update message)
-        syncProtocol.readSyncMessage(decoding.createDecoder(m), encoder, receiver)
-      })
+      // console.log('receive (' + sender.userID + '->' + receiver.userID + '):\n', syncProtocol.stringifySyncMessage(decoding.createDecoder(m), receiver))
+      // do not publish data created when this function is executed (could be ss2 or update message)
+      syncProtocol.readSyncMessage(decoding.createDecoder(m), encoder, receiver, receiver.tc)
      if (encoding.length(encoder) > 0) {
        // send reply message
-        sender._receive(encoding.toBuffer(encoder), receiver)
+        sender._receive(encoding.toUint8Array(encoder), receiver)
      }
      return true
    }
@@ -230,11 +214,13 @@ export class TestConnector {
 }

 /**
+ * @template T
 * @param {t.TestCase} tc
 * @param {{users?:number}} conf
- * @return {{testConnector:TestConnector,users:Array<TestYInstance>,array0:Y.Array<any>,array1:Y.Array<any>,array2:Y.Array<any>,map0:Y.Map<any>,map1:Y.Map<any>,map2:Y.Map<any>,map3:Y.Map<any>,text0:Y.Text,text1:Y.Text,text2:Y.Text,xml0:Y.XmlElement,xml1:Y.XmlElement,xml2:Y.XmlElement}}
+ * @param {InitTestObjectCallback<T>} [initTestObject]
+ * @return {{testObjects:Array<any>,testConnector:TestConnector,users:Array<TestYInstance>,array0:Y.Array<any>,array1:Y.Array<any>,array2:Y.Array<any>,map0:Y.Map<any>,map1:Y.Map<any>,map2:Y.Map<any>,map3:Y.Map<any>,text0:Y.Text,text1:Y.Text,text2:Y.Text,xml0:Y.XmlElement,xml1:Y.XmlElement,xml2:Y.XmlElement}}
 */
-export const init = (tc, { users = 5 } = {}) => {
+export const init = (tc, { users = 5 } = {}, initTestObject) => {
  /**
   * @type {Object<string,any>}
   */
@@ -254,8 +240,8 @@ export const init = (tc, { users = 5 } = {}) => {
    result['text' + i] = y.get('text', Y.Text)
  }
  testConnector.syncAll()
-  // @ts-ignore
-  return result
+  result.testObjects = result.users.map(initTestObject || (() => null))
+  return /** @type {any} */ (result)
 }

 /**
@@ -270,7 +256,7 @@ export const init = (tc, { users = 5 } = {}) => {
 export const compare = users => {
  users.forEach(u => u.connect())
  while (users[0].tc.flushAllMessages()) {}
-  const userArrayValues = users.map(u => u.getArray('array').toJSON().map(val => JSON.stringify(val)))
+  const userArrayValues = users.map(u => u.getArray('array').toJSON())
  const userMapValues = users.map(u => u.getMap('map').toJSON())
  const userXmlValues = users.map(u => u.get('xml', Y.XmlElement).toString())
  const userTextValues = users.map(u => u.getText('text').toDelta())
@@ -279,15 +265,29 @@ export const compare = users => {
    t.assert(u.store.pendingStack.length === 0)
    t.assert(u.store.pendingClientsStructRefs.size === 0)
  }
+  // Test Array iterator
+  t.compare(users[0].getArray('array').toArray(), Array.from(users[0].getArray('array')))
+  // Test Map iterator
+  const ymapkeys = Array.from(users[0].getMap('map').keys())
+  t.assert(ymapkeys.length === Object.keys(userMapValues[0]).length)
+  ymapkeys.forEach(key => t.assert(userMapValues[0].hasOwnProperty(key)))
+  /**
+   * @type {Object<string,any>}
+   */
+  const mapRes = {}
+  for (let [k, v] of users[0].getMap('map')) {
+    mapRes[k] = v instanceof Y.AbstractType ? v.toJSON() : v
+  }
+  t.compare(userMapValues[0], mapRes)
+  // Compare all users
  for (let i = 0; i < users.length - 1; i++) {
    t.compare(userArrayValues[i].length, users[i].getArray('array').length)
    t.compare(userArrayValues[i], userArrayValues[i + 1])
    t.compare(userMapValues[i], userMapValues[i + 1])
    t.compare(userXmlValues[i], userXmlValues[i + 1])
-    // @ts-ignore
-    t.compare(userTextValues[i].map(a => a.insert).join('').length, users[i].getText('text').length)
+    t.compare(userTextValues[i].map(/** @param {any} a */ a => typeof a.insert === 'string' ? a.insert : ' ').join('').length, users[i].getText('text').length)
    t.compare(userTextValues[i], userTextValues[i + 1])
-    t.compare(getStates(users[i].store), getStates(users[i + 1].store))
+    t.compare(getStateVector(users[i].store), getStateVector(users[i + 1].store))
    compareDS(createDeleteSetFromStructStore(users[i].store), createDeleteSetFromStructStore(users[i + 1].store))
    compareStructStores(users[i].store, users[i + 1].store)
  }
@@ -295,8 +295,8 @@ export const compare = users => {
 }

 /**
- * @param {AbstractItem?} a
- * @param {AbstractItem?} b
+ * @param {Item?} a
+ * @param {Item?} b
 * @return {boolean}
 */
 export const compareItemIDs = (a, b) => a === b || (a !== null && b != null && Y.compareIDs(a.id, b.id))
@@ -308,11 +308,10 @@ export const compareItemIDs = (a, b) => a === b || (a !== null && b != null && Y
 export const compareStructStores = (ss1, ss2) => {
  t.assert(ss1.clients.size === ss2.clients.size)
  for (const [client, structs1] of ss1.clients) {
-    const structs2 = ss2.clients.get(client)
+    const structs2 = /** @type {Array<Y.AbstractStruct>} */ (ss2.clients.get(client))
    t.assert(structs2 !== undefined && structs1.length === structs2.length)
    for (let i = 0; i < structs1.length; i++) {
      const s1 = structs1[i]
-      // @ts-ignore
      const s2 = structs2[i]
      // checks for abstract struct
      if (
@@ -323,9 +322,9 @@ export const compareStructStores = (ss1, ss2) => {
      ) {
        t.fail('Structs dont match')
      }
-      if (s1 instanceof AbstractItem) {
+      if (s1 instanceof Item) {
        if (
-          !(s2 instanceof AbstractItem) ||
+          !(s2 instanceof Item) ||
          !((s1.left === null && s2.left === null) || (s1.left !== null && s2.left !== null && Y.compareIDs(s1.left.lastId, s2.left.lastId))) ||
          !compareItemIDs(s1.right, s2.right) ||
          !Y.compareIDs(s1.origin, s2.origin) ||
@@ -351,11 +350,10 @@ export const compareStructStores = (ss1, ss2) => {
 export const compareDS = (ds1, ds2) => {
  t.assert(ds1.clients.size === ds2.clients.size)
  for (const [client, deleteItems1] of ds1.clients) {
-    const deleteItems2 = ds2.clients.get(client)
+    const deleteItems2 = /** @type {Array<DeleteItem>} */ (ds2.clients.get(client))
    t.assert(deleteItems2 !== undefined && deleteItems1.length === deleteItems2.length)
    for (let i = 0; i < deleteItems1.length; i++) {
      const di1 = deleteItems1[i]
-      // @ts-ignore
      const di2 = deleteItems2[i]
      if (di1.clock !== di2.clock || di1.len !== di2.len) {
        t.fail('DeleteSets dont match')
@@ -365,15 +363,24 @@ export const compareDS = (ds1, ds2) => {
 }

 /**
- * @param {t.TestCase} tc
- * @param {Array<function(TestYInstance,prng.PRNG):void>} mods
- * @param {number} iterations
+ * @template T
+ * @callback InitTestObjectCallback
+ * @param {TestYInstance} y
+ * @return {T}
 */
-export const applyRandomTests = (tc, mods, iterations) => {
+
+/**
+ * @template T
+ * @param {t.TestCase} tc
+ * @param {Array<function(Y.Doc,prng.PRNG,T):void>} mods
+ * @param {number} iterations
+ * @param {InitTestObjectCallback<T>} [initTestObject]
+ */
+export const applyRandomTests = (tc, mods, iterations, initTestObject) => {
  const gen = tc.prng
-  const result = init(tc, { users: 5 })
+  const result = init(tc, { users: 5 }, initTestObject || (() => null))
  const { testConnector, users } = result
-  for (var i = 0; i < iterations; i++) {
+  for (let i = 0; i < iterations; i++) {
    if (prng.int31(gen, 0, 100) <= 2) {
      // 2% chance to disconnect/reconnect a random user
      if (prng.bool(gen)) {
@@ -388,9 +395,9 @@ export const applyRandomTests = (tc, mods, iterations) => {
      // 50% chance to flush a random message
      testConnector.flushRandomMessage()
    }
-    let user = prng.oneOf(gen, users)
-    var test = prng.oneOf(gen, mods)
-    test(user, gen)
+    const user = prng.int31(gen, 0, users.length - 1)
+    const test = prng.oneOf(gen, mods)
+    test(users[user], gen, result.testObjects[user])
  }
  compare(users)
  return result
--- a/tests/undo-redo.tests.js
+++ b/tests/undo-redo.tests.js
@@ -0,0 +1,222 @@
+import { init, compare, applyRandomTests, Doc } from './testHelper.js' // eslint-disable-line
+
+import {
+  UndoManager
+} from '../src/internals.js'
+
+import * as Y from '../src/index.js'
+import * as t from 'lib0/testing.js'
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testUndoText = tc => {
+  const { testConnector, text0, text1 } = init(tc, { users: 3 })
+  const undoManager = new UndoManager(text0)
+  text0.insert(0, 'abc')
+  text1.insert(0, 'xyz')
+  testConnector.syncAll()
+  undoManager.undo()
+  t.assert(text0.toString() === 'xyz')
+  undoManager.redo()
+  t.assert(text0.toString() === 'abcxyz')
+  testConnector.syncAll()
+  text1.delete(0, 1)
+  testConnector.syncAll()
+  undoManager.undo()
+  t.assert(text0.toString() === 'xyz')
+  undoManager.redo()
+  t.assert(text0.toString() === 'bcxyz')
+  // test marks
+  text0.format(1, 3, { bold: true })
+  t.compare(text0.toDelta(), [{ insert: 'b' }, { insert: 'cxy', attributes: { bold: true } }, { insert: 'z' }])
+  undoManager.undo()
+  t.compare(text0.toDelta(), [{ insert: 'bcxyz' }])
+  undoManager.redo()
+  t.compare(text0.toDelta(), [{ insert: 'b' }, { insert: 'cxy', attributes: { bold: true } }, { insert: 'z' }])
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testUndoMap = tc => {
+  const { testConnector, map0, map1 } = init(tc, { users: 2 })
+  map0.set('a', 0)
+  const undoManager = new UndoManager(map0)
+  map0.set('a', 1)
+  undoManager.undo()
+  t.assert(map0.get('a') === 0)
+  undoManager.redo()
+  t.assert(map0.get('a') === 1)
+  // testing sub-types and if it can restore a whole type
+  const subType = new Y.Map()
+  map0.set('a', subType)
+  subType.set('x', 42)
+  t.compare(map0.toJSON(), /** @type {any} */ ({ 'a': { x: 42 } }))
+  undoManager.undo()
+  t.assert(map0.get('a') === 1)
+  undoManager.redo()
+  t.compare(map0.toJSON(), /** @type {any} */ ({ 'a': { x: 42 } }))
+  testConnector.syncAll()
+  // if content is overwritten by another user, undo operations should be skipped
+  map1.set('a', 44)
+  testConnector.syncAll()
+  undoManager.undo()
+  t.assert(map0.get('a') === 44)
+  undoManager.redo()
+  t.assert(map0.get('a') === 44)
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testUndoArray = tc => {
+  const { testConnector, array0, array1 } = init(tc, { users: 3 })
+  const undoManager = new UndoManager(array0)
+  array0.insert(0, [1, 2, 3])
+  array1.insert(0, [4, 5, 6])
+  testConnector.syncAll()
+  t.compare(array0.toArray(), [1, 2, 3, 4, 5, 6])
+  undoManager.undo()
+  t.compare(array0.toArray(), [4, 5, 6])
+  undoManager.redo()
+  t.compare(array0.toArray(), [1, 2, 3, 4, 5, 6])
+  testConnector.syncAll()
+  array1.delete(0, 1) // user1 deletes [1]
+  testConnector.syncAll()
+  undoManager.undo()
+  t.compare(array0.toArray(), [4, 5, 6])
+  undoManager.redo()
+  t.compare(array0.toArray(), [2, 3, 4, 5, 6])
+  array0.delete(0, 5)
+  // test nested structure
+  const ymap = new Y.Map()
+  array0.insert(0, [ymap])
+  t.compare(array0.toJSON(), [{}])
+  undoManager.stopCapturing()
+  ymap.set('a', 1)
+  t.compare(array0.toJSON(), [{ a: 1 }])
+  undoManager.undo()
+  t.compare(array0.toJSON(), [{}])
+  undoManager.undo()
+  t.compare(array0.toJSON(), [2, 3, 4, 5, 6])
+  undoManager.redo()
+  t.compare(array0.toJSON(), [{}])
+  undoManager.redo()
+  t.compare(array0.toJSON(), [{ a: 1 }])
+  testConnector.syncAll()
+  array1.get(0).set('b', 2)
+  testConnector.syncAll()
+  t.compare(array0.toJSON(), [{ a: 1, b: 2 }])
+  undoManager.undo()
+  t.compare(array0.toJSON(), [{ b: 2 }])
+  undoManager.undo()
+  t.compare(array0.toJSON(), [2, 3, 4, 5, 6])
+  undoManager.redo()
+  t.compare(array0.toJSON(), [{ b: 2 }])
+  undoManager.redo()
+  t.compare(array0.toJSON(), [{ a: 1, b: 2 }])
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testUndoXml = tc => {
+  const { xml0 } = init(tc, { users: 3 })
+  const undoManager = new UndoManager(xml0)
+  const child = new Y.XmlElement('p')
+  xml0.insert(0, [child])
+  const textchild = new Y.XmlText('content')
+  child.insert(0, [textchild])
+  t.assert(xml0.toString() === '<undefined><p>content</p></undefined>')
+  // format textchild and revert that change
+  undoManager.stopCapturing()
+  textchild.format(3, 4, { bold: {} })
+  t.assert(xml0.toString() === '<undefined><p>con<bold>tent</bold></p></undefined>')
+  undoManager.undo()
+  t.assert(xml0.toString() === '<undefined><p>content</p></undefined>')
+  undoManager.redo()
+  t.assert(xml0.toString() === '<undefined><p>con<bold>tent</bold></p></undefined>')
+  xml0.delete(0, 1)
+  t.assert(xml0.toString() === '<undefined></undefined>')
+  undoManager.undo()
+  t.assert(xml0.toString() === '<undefined><p>con<bold>tent</bold></p></undefined>')
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testUndoEvents = tc => {
+  const { text0 } = init(tc, { users: 3 })
+  const undoManager = new UndoManager(text0)
+  let counter = 0
+  let receivedMetadata = -1
+  undoManager.on('stack-item-added', /** @param {any} event */ event => {
+    t.assert(event.type != null)
+    event.stackItem.meta.set('test', counter++)
+  })
+  undoManager.on('stack-item-popped', /** @param {any} event */ event => {
+    t.assert(event.type != null)
+    receivedMetadata = event.stackItem.meta.get('test')
+  })
+  text0.insert(0, 'abc')
+  undoManager.undo()
+  t.assert(receivedMetadata === 0)
+  undoManager.redo()
+  t.assert(receivedMetadata === 1)
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testTrackClass = tc => {
+  const { users, text0 } = init(tc, { users: 3 })
+  // only track origins that are numbers
+  const undoManager = new UndoManager(text0, { trackedOrigins: new Set([Number]) })
+  users[0].transact(() => {
+    text0.insert(0, 'abc')
+  }, 42)
+  t.assert(text0.toString() === 'abc')
+  undoManager.undo()
+  t.assert(text0.toString() === '')
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testTypeScope = tc => {
+  const { array0 } = init(tc, { users: 3 })
+  // only track origins that are numbers
+  const text0 = new Y.Text()
+  const text1 = new Y.Text()
+  array0.insert(0, [text0, text1])
+  const undoManager = new UndoManager(text0)
+  const undoManagerBoth = new UndoManager([text0, text1])
+  text1.insert(0, 'abc')
+  t.assert(undoManager.undoStack.length === 0)
+  t.assert(undoManagerBoth.undoStack.length === 1)
+  t.assert(text1.toString() === 'abc')
+  undoManager.undo()
+  t.assert(text1.toString() === 'abc')
+  undoManagerBoth.undo()
+  t.assert(text1.toString() === '')
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testUndoDeleteFilter = tc => {
+  /**
+   * @type {Array<Y.Map<any>>}
+   */
+  const array0 = /** @type {any} */ (init(tc, { users: 3 }).array0)
+  const undoManager = new UndoManager(array0, { deleteFilter: item => !(item instanceof Y.Item) || (item.content instanceof Y.ContentType && item.content.type._map.size === 0) })
+  const map0 = new Y.Map()
+  map0.set('hi', 1)
+  const map1 = new Y.Map()
+  array0.insert(0, [map0, map1])
+  undoManager.undo()
+  t.assert(array0.length === 1)
+  array0.get(0)
+  t.assert(Array.from(array0.get(0).keys()).length === 1)
+}
--- a/tests/y-array.tests.js
+++ b/tests/y-array.tests.js
@@ -1,4 +1,4 @@
-import { init, compare, applyRandomTests, TestYInstance } from './testHelper.js' // eslint-disable-line
+import { init, compare, applyRandomTests, Doc } from './testHelper.js' // eslint-disable-line

 import * as Y from '../src/index.js'
 import * as t from 'lib0/testing.js'
@@ -25,10 +25,10 @@ export const testDeleteInsert = tc => {
 */
 export const testInsertThreeElementsTryRegetProperty = tc => {
  const { testConnector, users, array0, array1 } = init(tc, { users: 2 })
-  array0.insert(0, [1, 2, 3])
-  t.compare(array0.toJSON(), [1, 2, 3], '.toJSON() works')
+  array0.insert(0, [1, true, false])
+  t.compare(array0.toJSON(), [1, true, false], '.toJSON() works')
  testConnector.flushAllMessages()
-  t.compare(array1.toJSON(), [1, 2, 3], '.toJSON() works after sync')
+  t.compare(array1.toJSON(), [1, true, false], '.toJSON() works after sync')
  compare(users)
 }

@@ -144,6 +144,32 @@ export const testInsertAndDeleteEvents = tc => {
  compare(users)
 }

+/**
+ * @param {t.TestCase} tc
+ */
+export const testNestedObserverEvents = tc => {
+  const { array0, users } = init(tc, { users: 2 })
+  /**
+   * @type {Array<number>}
+   */
+  const vals = []
+  array0.observe(e => {
+    if (array0.length === 1) {
+      // inserting, will call this observer again
+      // we expect that this observer is called after this event handler finishedn
+      array0.insert(1, [1])
+      vals.push(0)
+    } else {
+      // this should be called the second time an element is inserted (above case)
+      vals.push(1)
+    }
+  })
+  array0.insert(0, [0])
+  t.compareArrays(vals, [0, 1])
+  t.compareArrays(array0.toArray(), [0, 1])
+  compare(users)
+}
+
 /**
 * @param {t.TestCase} tc
 */
@@ -184,6 +210,24 @@ export const testInsertAndDeleteEventsForTypes2 = tc => {
  compare(users)
 }

+/**
+ * This issue has been reported here https://github.com/y-js/yjs/issues/155
+ * @param {t.TestCase} tc
+ */
+export const testNewChildDoesNotEmitEventInTransaction = tc => {
+  const { array0, users } = init(tc, { users: 2 })
+  let fired = false
+  users[0].transact(() => {
+    const newMap = new Y.Map()
+    newMap.observe(() => {
+      fired = true
+    })
+    array0.insert(0, [newMap])
+    newMap.set('tst', 42)
+  })
+  t.assert(!fired, 'Event does not trigger')
+}
+
 /**
 * @param {t.TestCase} tc
 */
@@ -237,7 +281,7 @@ export const testEventTargetIsSetCorrectlyOnRemote = tc => {
 * @param {t.TestCase} tc
 */
 export const testIteratingArrayContainingTypes = tc => {
-  const y = new Y.Y()
+  const y = new Y.Doc()
  const arr = y.getArray('arr')
  const numItems = 10
  for (let i = 0; i < numItems; i++) {
@@ -256,7 +300,7 @@ let _uniqueNumber = 0
 const getUniqueNumber = () => _uniqueNumber++

 /**
- * @type {Array<function(TestYInstance,prng.PRNG):void>}
+ * @type {Array<function(Doc,prng.PRNG,any):void>}
 */
 const arrayTransactions = [
  function insert (user, gen) {
@@ -309,8 +353,8 @@ const arrayTransactions = [
 /**
 * @param {t.TestCase} tc
 */
-export const testRepeatGeneratingYarrayTests20 = tc => {
-  applyRandomTests(tc, arrayTransactions, 3)
+export const testRepeatGeneratingYarrayTests4 = tc => {
+  applyRandomTests(tc, arrayTransactions, 4)
 }

 /**
--- a/tests/y-map.tests.js
+++ b/tests/y-map.tests.js
@@ -1,4 +1,4 @@
-import { init, compare, applyRandomTests, TestYInstance } from './testHelper.js' // eslint-disable-line
+import { init, compare, applyRandomTests, Doc } from './testHelper.js' // eslint-disable-line

 import {
  compareIDs
@@ -19,6 +19,8 @@ export const testBasicMapTests = tc => {
  map0.set('string', 'hello Y')
  map0.set('object', { key: { key2: 'value' } })
  map0.set('y-map', new Y.Map())
+  map0.set('boolean1', true)
+  map0.set('boolean0', false)
  const map = map0.get('y-map')
  map.set('y-array', new Y.Array())
  const array = map.get('y-array')
@@ -27,6 +29,8 @@ export const testBasicMapTests = tc => {

  t.assert(map0.get('number') === 1, 'client 0 computed the change (number)')
  t.assert(map0.get('string') === 'hello Y', 'client 0 computed the change (string)')
+  t.assert(map0.get('boolean0') === false, 'client 0 computed the change (boolean)')
+  t.assert(map0.get('boolean1') === true, 'client 0 computed the change (boolean)')
  t.compare(map0.get('object'), { key: { key2: 'value' } }, 'client 0 computed the change (object)')
  t.assert(map0.get('y-map').get('y-array').get(0) === -1, 'client 0 computed the change (type)')

@@ -35,12 +39,16 @@ export const testBasicMapTests = tc => {

  t.assert(map1.get('number') === 1, 'client 1 received the update (number)')
  t.assert(map1.get('string') === 'hello Y', 'client 1 received the update (string)')
+  t.assert(map1.get('boolean0') === false, 'client 1 computed the change (boolean)')
+  t.assert(map1.get('boolean1') === true, 'client 1 computed the change (boolean)')
  t.compare(map1.get('object'), { key: { key2: 'value' } }, 'client 1 received the update (object)')
  t.assert(map1.get('y-map').get('y-array').get(0) === -1, 'client 1 received the update (type)')

  // compare disconnected user
  t.assert(map2.get('number') === 1, 'client 2 received the update (number) - was disconnected')
  t.assert(map2.get('string') === 'hello Y', 'client 2 received the update (string) - was disconnected')
+  t.assert(map2.get('boolean0') === false, 'client 2 computed the change (boolean)')
+  t.assert(map2.get('boolean1') === true, 'client 2 computed the change (boolean)')
  t.compare(map2.get('object'), { key: { key2: 'value' } }, 'client 2 received the update (object) - was disconnected')
  t.assert(map2.get('y-map').get('y-array').get(0) === -1, 'client 2 received the update (type) - was disconnected')
  compare(users)
@@ -320,7 +328,7 @@ export const testYmapEventHasCorrectValueWhenSettingAPrimitiveFromOtherUser = tc
 }

 /**
- * @type {Array<function(TestYInstance,prng.PRNG):void>}
+ * @type {Array<function(Doc,prng.PRNG):void>}
 */
 const mapTransactions = [
  function set (user, gen) {
--- a/tests/y-text.tests.js
+++ b/tests/y-text.tests.js
@@ -27,6 +27,13 @@ export const testBasicInsertAndDelete = tc => {
  text0.delete(1, 1)
  t.assert(text0.toString() === 'b', 'Basic delete works (position 1)')
  t.compare(delta, [{ retain: 1 }, { delete: 1 }])
+
+  users[0].transact(() => {
+    text0.insert(0, '1')
+    text0.delete(0, 1)
+  })
+  t.compare(delta, [])
+
  compare(users)
 }

@@ -56,7 +63,7 @@ export const testBasicFormat = tc => {
  t.compare(text0.toDelta(), [{ insert: 'zb', attributes: { bold: true } }])
  t.compare(delta, [{ insert: 'z', attributes: { bold: true } }])
  // @ts-ignore
-  t.assert(text0._start.right.right.right.string === 'b', 'Does not insert duplicate attribute marker')
+  t.assert(text0._start.right.right.right.content.str === 'b', 'Does not insert duplicate attribute marker')
  text0.insert(0, 'y')
  t.assert(text0.toString() === 'yzb')
  t.compare(text0.toDelta(), [{ insert: 'y' }, { insert: 'zb', attributes: { bold: true } }])
@@ -67,3 +74,16 @@ export const testBasicFormat = tc => {
  t.compare(delta, [{ retain: 1 }, { retain: 1, attributes: { bold: null } }])
  compare(users)
 }
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testGetDeltaWithEmbeds = tc => {
+  const { text0 } = init(tc, { users: 1 })
+  text0.applyDelta([{
+    insert: {linebreak: 's'}
+  }])
+  t.compare(text0.toDelta(), [{
+    insert: {linebreak: 's'}
+  }])
+}
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -36,8 +36,10 @@

    /* Module Resolution Options */
    "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
-    // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
-    // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
+    "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
+    "paths": {
+      "yjs": ["./src/index.js"]
+    },                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
    // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
    // "typeRoots": [],                       /* List of folders to include type definitions from. */
    // "types": [],                           /* Type declaration files to be included in compilation. */
@@ -58,5 +60,5 @@
    // "types": ["./src/utils/typedefs.js"]
  },
  "include": ["./src/**/*", "./tests/**/*"],
-  "exclude": ["../lib0/**/*", "node_modules"]
+  "exclude": ["../lib0/**/*", "node_modules/**/*", "dist", "dist/**/*.js"]
 }
Author	SHA1	Message	Date
Kevin Jahns	fc4d6165b4	13.0.0-96	2019-08-20 22:29:56 +02:00
Kevin Jahns	251c8aaefc	UndoManager configuration to filter deletes	2019-08-20 22:28:49 +02:00
Kevin Jahns	1337d38ada	13.0.0-95	2019-08-09 01:18:15 +02:00
Kevin Jahns	f5c66e41cb	audit	2019-08-09 01:16:40 +02:00
Kevin Jahns	0e7da017fe	Use lib0/any-encoding instead of JSON	2019-08-09 01:15:46 +02:00
Kevin Jahns	36203af88e	should not rely on all deconstructing features because not all parsers support it	2019-06-29 14:47:34 +02:00
Kevin Jahns	dd2b8bc6c7	13.0.0-94	2019-06-25 11:57:50 +02:00
Kevin Jahns	463065ac21	UndoManager: keep item before item is deleted (fixes some edge cases of followRedo)	2019-06-25 11:56:41 +02:00
Kevin Jahns	d064e6e96e	UndoManager accepts an array of types as scope. Implements #156	2019-06-25 02:26:18 +02:00
Kevin Jahns	b1ed2df208	proper TOC links	2019-06-25 00:10:12 +02:00
Kevin Jahns	1fe4ef135c	13.0.0-93	2019-06-24 23:06:11 +02:00
Kevin Jahns	e376b5d472	UndoManager fixes	2019-06-24 23:04:53 +02:00
Kevin Jahns	952a9b2c41	13.0.0-92	2019-06-23 13:05:30 +02:00
Kevin Jahns	03458dc641	Port Undo/Redo approach with a clean API	2019-06-23 13:04:14 +02:00
Kevin Jahns	14df5b72af	fix consistency bug - ref.toStruct does not correctly create GC when offset is specified	2019-06-18 18:46:19 +02:00
Kevin Jahns	338968031b	13.0.0-91	2019-06-18 18:05:39 +02:00
Kevin Jahns	1aac245b93	New types dont fire events - fixes #155	2019-06-18 17:41:19 +02:00
Kevin Jahns	1faff323c1	13.0.0-90	2019-06-14 16:00:02 +02:00
Kevin Jahns	e7280c7ae2	allow case sensitive yxml nodes	2019-06-14 15:59:00 +02:00
Kevin Jahns	4c38619b5d	13.0.0-89	2019-06-13 10:33:35 +02:00
Kevin Jahns	b4e5c5cc1f	Correctly insert embed when using YText.applyDelta	2019-06-13 10:30:39 +02:00
Kevin Jahns	b0dbd84f7f	lint markdown	2019-06-13 10:28:30 +02:00
Kevin Jahns	4a990963d9	13.0.0-88	2019-06-05 18:37:21 +02:00
Kevin Jahns	7e7c9d5b11	add relevant type information	2019-06-05 14:53:00 +02:00
Kevin Jahns	775f6eed1d	fix websocket example	2019-06-02 15:16:14 +02:00
Kevin Jahns	1e83b9418c	13.0.0-87	2019-05-28 14:20:44 +02:00
Kevin Jahns	ac3f672c80	Merge branch 'master' of github.com:y-js/yjs	2019-05-28 14:19:11 +02:00
Kevin Jahns	2192aa5821	Use generic Item with typed content to reduce cache misses	2019-05-28 14:18:20 +02:00
Kevin Jahns	70bb523005	Merge branch 'master' of github.com:y-js/yjs	2019-05-27 12:50:21 +02:00
Kevin Jahns	10ce6de57a	import statement fix	2019-05-27 12:50:12 +02:00
Kevin Jahns	3fba4f25a5	Merge pull request #153 from calibr/124-text-embeds process embeds in YText.toDelta	2019-05-25 13:04:10 +02:00
Kevin Jahns	66c35d8499	testing: do not stringify array values before comparing	2019-05-25 12:54:30 +02:00
Kevin Jahns	4c14157dcf	13.0.0-86	2019-05-25 12:50:05 +02:00
Kevin Jahns	ef6c382e20	fix array iterator on merged content. fixes #152	2019-05-25 12:49:08 +02:00
calibr	ee45b4fdd6	process embeds in YText.toDelta	2019-05-25 13:48:57 +03:00
Kevin Jahns	668e9e8a9b	13.0.0-85	2019-05-25 03:13:54 +02:00
Kevin Jahns	37a6d68543	implement support for boolean values. fixes #151	2019-05-25 03:12:56 +02:00
Kevin Jahns	f893198769	remove examples. fixes #149	2019-05-22 17:32:51 +02:00
Kevin Jahns	d3ee1a0ec2	Add editor support to v13 readme	2019-05-22 01:26:13 +02:00
Kevin Jahns	d6593412a2	13.0.0-84	2019-05-19 21:49:36 +02:00
Kevin Jahns	d31bf36531	use generated esm module by default	2019-05-19 21:48:09 +02:00
Kevin Jahns	a485f550db	13.0.0-83	2019-05-19 20:59:56 +02:00
Kevin Jahns	0610b16227	bump lib0 for webpack compatibility	2019-05-19 20:43:18 +02:00
Kevin Jahns	72e470c5f0	Fix ytext event.delta - items that are synced and deleted When items are added and deleted in the same transaction, event.delta would recognize them as added (though they are actually deleted). Now it just ignores them.	2019-05-19 20:42:53 +02:00
Kevin Jahns	4d12a02e2f	fix offset in state vector	2019-05-16 12:31:53 +02:00
Kevin Jahns	4a7d6f0a2d	fix sorting bug that only affects older node versions (probably because old sorting algorithms are not stable)	2019-05-14 15:21:34 +02:00
Kevin Jahns	c80f446b5f	README: update provider tutorial	2019-05-12 11:18:43 +02:00
Kevin Jahns	81a529d8dc	update getting started yjs version	2019-05-07 15:43:09 +02:00
Kevin Jahns	4f0ab78914	13.0.0-82	2019-05-07 13:54:00 +02:00
Kevin Jahns	8c36f67f0b	rework and document api	2019-05-07 13:44:23 +02:00
Kevin Jahns	77687d94e6	13.0.0-81	2019-04-28 17:32:05 +02:00
Kevin Jahns	4644511303	bump y-protocols dependency	2019-04-28 17:30:52 +02:00
Kevin Jahns	20005eecdb	Merge deleted items more efficiently. Previously deleted items were simply added to transaction._mergeStructs. But this inherently inefficient as it will splice the struct store for every item. Now Yjs iterates over transaction.ds and tries to merge structs. It iterates from right to left so merging should be more efficient that before. But more work needs to be done. For example we could set structs[i] = null and filter the structs after merging is done.	2019-04-28 17:20:35 +02:00
Kevin Jahns	c9dda245bf	v13 api docs	2019-04-28 02:53:25 +02:00
Kevin Jahns	1417470156	update demos link	2019-04-27 03:44:48 +02:00
Kevin Jahns	584e5dfd40	Link to v13 docs from README	2019-04-27 03:35:44 +02:00
Kevin Jahns	805acbb9f5	13.0.0-80	2019-04-26 19:55:14 +02:00
Kevin Jahns	32c4c09072	update parent._map when splitting an item	2019-04-26 19:54:00 +02:00
Kevin Jahns	8c5a06bbf8	fix gc when item is deleted in observer call	2019-04-26 18:37:38 +02:00
Kevin Jahns	a336cc167c	order observer and transaction cleanups after one another	2019-04-26 13:31:00 +02:00
Kevin Jahns	21d86cd2be	Delete all children of ItemType when it is deleted	2019-04-26 12:29:28 +02:00
Kevin Jahns	1d0f9faa91	AbstractItem.mergeWith helper outsourced into separate function	2019-04-24 18:10:33 +02:00
Kevin Jahns	45237571b7	gc more efficiently	2019-04-23 20:51:32 +02:00
Kevin Jahns	bb6f6cd141	13.0.0-79	2019-04-20 00:03:30 +02:00
Kevin Jahns	729c1f16b8	fix test provider	2019-04-20 00:02:40 +02:00
Kevin Jahns	b6059704aa	update dependencies	2019-04-20 00:00:09 +02:00