.babelrc

@@ -0,0 +1,12 @@
+{
+  "presets": [
+    ["latest", {
+      "es2015": {
+        "modules": false
+      }
+    }]
+  ],
+  "plugins": [
+    "external-helpers"
+  ]
+}

.esdoc.json

@@ -0,0 +1,10 @@
+{
+  "source": "./src",
+  "destination": "./docs",
+  "plugins": [{
+    "name": "esdoc-standard-plugin",
+    "option": {
+      "accessor": {"access": ["public"], "autoPrivate": true}
+    }
+  }]
+}

.flowconfig

@@ -0,0 +1,14 @@
+[ignore]
+.*/node_modules/.*
+.*/dist/.*
+.*/build/.*
+
+[include]
+./src/
+./tests-lib/
+./test/
+
+[libs]
+./declarations/
+
+[options]

.github/workflows/node.js.yml

@@ -1,31 +0,0 @@
-# This workflow will do a clean install of node dependencies, build the source code and run tests across different versions of node
-# For more information see: https://help.github.com/actions/language-and-framework-guides/using-nodejs-with-github-actions
-
-name: Node.js CI
-
-on:
-  push:
-    branches: [ main ]
-  pull_request:
-    branches: [ main ]
-
-jobs:
-  build:
-
-    runs-on: ubuntu-latest
-
-    strategy:
-      matrix:
-        node-version: [16.x, 20.x]
-
-    steps:
-    - uses: actions/checkout@v4
-    - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v3
-      with:
-        node-version: ${{ matrix.node-version }}
-    - run: npm ci
-    - run: npm run lint
-    - run: npm run test
-      env:
-        CI: true

.gitignore

@@ -1,4 +1,7 @@
 node_modules
-dist
-.vscode
+bower_components
 docs
+/y.*
+/examples/yjs-dist.js*
+.vscode
+.yjsPersisted

.jsdoc.json

@@ -1,52 +0,0 @@
-{
-  "sourceType": "module",
-  "tags": {
-    "allowUnknownTags": true,
-    "dictionaries": ["jsdoc"]
-  },
-  "source": {
-    "include": ["./src"],
-    "includePattern": ".js$"
-  },
-  "plugins": [
-    "plugins/markdown"
-  ],
-  "templates": {
-    "referenceTitle": "Yjs",
-    "disableSort": false,
-    "useCollapsibles": true,
-    "collapse": true,
-    "resources": {
-      "yjs.dev": "Website",
-      "docs.yjs.dev": "Docs",
-      "discuss.yjs.dev": "Forum",
-      "https://gitter.im/Yjs/community": "Chat"
-    },
-    "logo": {
-      "url": "https://yjs.dev/images/logo/yjs-512x512.png",
-      "width": "162px",
-      "height": "162px",
-      "link": "/"
-    },
-    "tabNames": {
-      "api": "API",
-      "tutorials": "Examples"
-    },
-    "footerText": "Shared Editing",
-    "css": [
-      "./style.css"
-    ],
-    "default": {
-      "staticFiles": {
-          "include": []
-      }
-    }
-  },
-  "opts": {
-    "destination": "./docs/",
-    "encoding": "utf8",
-    "private": false,
-    "recurse": true,
-    "template": "./node_modules/tui-jsdoc-template"
-  }
-}

.markdownlint.json

@@ -1,4 +0,0 @@
-{
-  "default": true,
-  "no-inline-html": false
-}

INTERNALS.md

@@ -1,179 +0,0 @@
-# Yjs Internals
-
-This document roughly explains how Yjs works internally. There is a complete
-walkthrough of the Yjs codebase available as a recording:
-https://youtu.be/0l5XgnQ6rB4
-
-The Yjs CRDT algorithm is described in the [YATA
-paper](https://www.researchgate.net/publication/310212186_Near_Real-Time_Peer-to-Peer_Shared_Editing_on_Extensible_Data_Types)
-from 2016. For an algorithmic view of how it works, the paper is a reasonable
-place to start. There are a handful of small improvements implemented in Yjs
-which aren't described in the paper. The most notable is that items have an
-`originRight` as well as an `origin` property, which improves performance when
-many concurrent inserts happen after the same character.
-
-At its heart, Yjs is a list CRDT. Everything is squeezed into a list in order to
-reuse the CRDT resolution algorithm:
-
-- Arrays are easy - they're lists of arbitrary items.
-- Text is a list of characters, optionally punctuated by formatting markers and
-  embeds for rich text support. Several characters can be wrapped in a single
-linked list `Item` (this is also known as the compound representation of
-CRDTs). More information about this in [this blog
-article](https://blog.kevinjahns.de/are-crdts-suitable-for-shared-editing/).
-- Maps are lists of entries. The last inserted entry for each key is used, and
-  all other duplicates for each key are flagged as deleted.
-
-Each client is assigned a unique *clientID* property on first insert. This is a
-random 53-bit integer (53 bits because that fits in the javascript safe integer
-range \[JavaScript uses IEEE 754 floats\]).
-
-## List items
-
-Each item in a Yjs list is made up of two objects:
-
-- An `Item` (*src/structs/Item.js*). This is used to relate the item to other
-  adjacent items.
-- An object in the `AbstractType` hierarchy (subclasses of
-  *src/types/AbstractType.js* - eg `YText`). This stores the actual content in
-the Yjs document.
-
-The item and type object pair have a 1-1 mapping. The item's `content` field
-references the AbstractType object and the AbstractType object's `_item` field
-references the item.
-
-Everything inserted in a Yjs document is given a unique ID, formed from a
-*ID(clientID, clock)* pair (also known as a [Lamport
-Timestamp](https://en.wikipedia.org/wiki/Lamport_timestamp)). The clock counts
-up from 0 with the first inserted character or item a client makes. This is
-similar to automerge's operation IDs, but note that the clock is only
-incremented by inserts. Deletes are handled in a very different way (see
-below).
-
-If a run of characters is inserted into a document (eg `"abc"`), the clock will
-be incremented for each character (eg 3 times here). But Yjs will only add a
-single `Item` into the list. This has no effect on the core CRDT algorithm, but
-the optimization dramatically decreases the number of javascript objects
-created during normal text editing. This optimization only applies if the
-characters share the same clientID, they're inserted in order, and all
-characters have either been deleted or all characters are not deleted. The item
-will be split if the run is interrupted for any reason (eg a character in the
-middle of the run is deleted).
-
-When an item is created, it stores a reference to the IDs of the preceding and
-succeeding item. These are stored in the item's `origin` and `originRight`
-fields, respectively. These are used when peers concurrently insert at the same
-location in a document. Though quite rare in practice, Yjs needs to make sure
-the list items always resolve to the same order on all peers. The actual logic
-is relatively simple - its only a couple dozen lines of code and it lives in
-the `Item#integrate()` method. The YATA paper has much more detail on this
-algorithm.
-
-### Item Storage
-
-The items themselves are stored in two data structures and a cache:
-
-- The items are stored in a tree of doubly-linked lists in *document order*.
-  Each item has `left` and `right` properties linking to its siblings in the
-document. Items also have a `parent` property to reference their parent in the
-document tree (null at the root). (And you can access an item's children, if
-any, through `item.content`).
-- All items are referenced in *insertion order* inside the struct store
-  (*src/utils/StructStore.js*). This references the list of items inserted by
-for each client, in chronological order. This is used to find an item in the
-tree with a given ID (using a binary search). It is also used to efficiently
-gather the operations a peer is missing during sync (more on this below).
-
-When a local insert happens, Yjs needs to map the insert position in the
-document (eg position 1000) to an ID. With just the linked list, this would
-require a slow O(n) linear scan of the list. But when editing a document, most
-inserts are either at the same position as the last insert, or nearby. To
-improve performance, Yjs stores a cache of the 80 most recently looked up
-insert positions in the document. This is consulted and updated when a position
-is looked up to improve performance in the average case. The cache is updated
-using a heuristic that is still changing (currently, it is updated when a new
-position significantly diverges from existing markers in the cache). Internally
-this is referred to as the skip list / fast search marker.
-
-### Deletions
-
-Deletions in Yjs are treated very differently from insertions. Insertions are
-implemented as a sequential operation based CRDT, but deletions are treated as
-a simpler state based CRDT.
-
-When an item has been deleted by any peer, at any point in history, it is
-flagged as deleted on the item. (Internally Yjs uses the `info` bitfield.) Yjs
-does not record metadata about a deletion:
-
-- No data is kept on *when* an item was deleted, or which user deleted it.
-- The struct store does not contain deletion records
-- The clientID's clock is not incremented
-
-If garbage collection is enabled in Yjs, when an object is deleted its content
-is discarded. If a deleted object contains children (eg a field is deleted in
-an object), the content is replaced with a `GC` object (*src/structs/GC.js*).
-This is a very lightweight structure - it only stores the length of the removed
-content.
-
-Yjs has some special logic to share which content in a document has been
-deleted:
-
-- When a delete happens, as well as marking the item, the deleted IDs are
-  listed locally within the transaction. (See below for more information about
-transactions.) When a transaction has been committed locally, the set of
-deleted items is appended to a transaction's update message.
-- A snapshot (a marked point in time in the Yjs history) is specified using
-  both the set of (clientID, clock) pairs *and* the set of all deleted item
-IDs. The deleted set is O(n), but because deletions usually happen in runs,
-this data set is usually tiny in practice. (The real world editing trace from
-the B4 benchmark document contains 182k inserts and 77k deleted characters. The
-deleted set size in a snapshot is only 4.5Kb).
-
-## Transactions
-
-All updates in Yjs happen within a *transaction*. (Defined in
-*src/utils/Transaction.js*.)
-
-The transaction collects a set of updates to the Yjs document to be applied on
-remote peers atomically. Once a transaction has been committed locally, it
-generates a compressed *update message* which is broadcast to synchronized
-remote peers to notify them of the local change. The update message contains:
-
-- The set of newly inserted items
-- The set of items deleted within the transaction.
-
-## Network protocol
-
-The network protocol is not really a part of Yjs. There are a few relevant
-concepts that can be used to create a custom network protocol:
-
-* `update`: The Yjs document can be encoded to an *update* object that can be
-  parsed to reconstruct the document. Also every change on the document fires
-an incremental document update that allows clients to sync with each other.
-The update object is a Uint8Array that efficiently encodes `Item` objects and
-the delete set.
-* `state vector`: A state vector defines the known state of each user (a set of
-  tuples `(client, clock)`). This object is also efficiently encoded as a
-Uint8Array.
-
-The client can ask a remote client for missing document updates by sending
-their state vector (often referred to as *sync step 1*). The remote peer can
-compute the missing `Item` objects using the `clocks` of the respective clients
-and compute a minimal update message that reflects all missing updates (sync
-step 2).
-
-An implementation of the syncing process is in
-[y-protocols](https://github.com/yjs/y-protocols).
-
-## Snapshots
-
-A snapshot can be used to restore an old document state. It is a `state vector`
-\+ `delete set`. A client can restore an old document state by iterating through
-the sequence CRDT and ignoring all Items that have an `id.clock >
-stateVector[id.client].clock`. Instead of using `item.deleted` the client will
-use the delete set to find out if an item was deleted or not.
-
-It is not recommended to restore an old document state using snapshots,
-although that would certainly be possible. Instead, the old state should be
-computed by iterating through the newest state and using the additional
-information from the state vector.

LICENSE

@@ -1,7 +1,7 @@
 The MIT License (MIT)
 
-Copyright (c) 2023
-  - Kevin Jahns <kevin.jahns@protonmail.com>.
+Copyright (c) 2014
+  - Kevin Jahns <kevin.jahns@rwth-aachen.de>.
   - Chair of Computer Science 5 (Databases & Information Systems), RWTH Aachen University, Germany
 
 Permission is hereby granted, free of charge, to any person obtaining a copy

examples/ace/index.html

@@ -0,0 +1,33 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <style type="text/css" media="screen">
+    #aceContainer {
+        position: absolute;
+        top: 0;
+        right: 0;
+        bottom: 0;
+        left: 0;
+    }
+    .inserted {
+      position:absolute;
+      z-index:20;
+      background-color: #FFC107;
+    }
+    .deleted {
+      position:absolute;
+      z-index:20;
+      background-color: #FFC107;
+    }
+    </style>
+  </head>
+  <body>
+
+    <div id="aceContainer"></div>
+    <script src="../../y.js"></script>
+    <script src='../../../y-websockets-client/y-websockets-client.js'></script>
+    <script src="../bower_components/ace-builds/src/ace.js"></script>
+
+    <script src="./index.js"></script>
+  </body>
+</html>

examples/ace/index.js

@@ -0,0 +1,17 @@
+/* global Y, ace */
+
+let y = new Y('ace-example', {
+  connector: {
+    name: 'websockets-client',
+    url: 'http://127.0.0.1:1234'
+  }
+})
+
+window.yAce = y
+
+// bind the textarea to a shared text element
+var editor = ace.edit('aceContainer')
+editor.setTheme('ace/theme/chrome')
+editor.getSession().setMode('ace/mode/javascript')
+
+y.define('ace', Y.Text).bindAce(editor)

examples/bower.json

@@ -0,0 +1,19 @@
+{
+  "name": "yjs-examples",
+  "version": "0.0.0",
+  "homepage": "y-js.org",
+  "authors": [
+    "Kevin Jahns <kevin.jahns@rwth-aachen.de>"
+  ],
+  "description": "Examples for Yjs",
+  "license": "MIT",
+  "ignore": [],
+  "dependencies": {
+    "quill": "^1.0.0-rc.2",
+    "ace": "~1.2.3",
+    "ace-builds": "~1.2.3",
+    "jquery": "~2.2.2",
+    "d3": "^3.5.16",
+    "codemirror": "^5.25.0"
+  }
+}

examples/chat/index.html

@@ -0,0 +1,19 @@
+<!DOCTYPE html>
+<html>
+  <body>
+    <style>
+      #chat p span {
+        color: blue;
+      }
+    </style>
+    <div id="chat"></div>
+    <form id="chatform">
+      <input name="username" type="text" style="width:15%;">
+      <input name="message" type="text" style="width:60%;">
+      <input type="submit" value="Send">
+    </form>
+    <script src="../../y.js"></script>
+    <script src='../../../y-websockets-client/y-websockets-client.js'></script>
+    <script src="./index.js"></script>
+  </body>
+</html>

examples/chat/index.js

@@ -0,0 +1,65 @@
+/* global Y */
+
+let y = new Y('chat-example', {
+  connector: {
+    name: 'websockets-client',
+    url: 'http://127.0.0.1:1234'
+  }
+})
+
+window.yChat = y
+
+let chatprotocol = y.define('chatprotocol', Y.Array)
+
+let chatcontainer = document.querySelector('#chat')
+
+// This functions inserts a message at the specified position in the DOM
+function appendMessage (message, position) {
+  var p = document.createElement('p')
+  var uname = document.createElement('span')
+  uname.appendChild(document.createTextNode(message.username + ': '))
+  p.appendChild(uname)
+  p.appendChild(document.createTextNode(message.message))
+  chatcontainer.insertBefore(p, chatcontainer.children[position] || null)
+}
+
+// This function makes sure that only 7 messages exist in the chat history.
+// The rest is deleted
+function cleanupChat () {
+  if (chatprotocol.length > 7) {
+    chatprotocol.delete(0, chatprotocol.length - 7)
+  }
+}
+cleanupChat()
+
+// Insert the initial content
+chatprotocol.toArray().forEach(appendMessage)
+
+// whenever content changes, make sure to reflect the changes in the DOM
+chatprotocol.observe(function (event) {
+  // concurrent insertions may result in a history > 7, so cleanup here
+  cleanupChat()
+  chatcontainer.innerHTML = ''
+  chatprotocol.toArray().forEach(appendMessage)
+})
+document.querySelector('#chatform').onsubmit = function (event) {
+  // the form is submitted
+  var message = {
+    username: this.querySelector('[name=username]').value,
+    message: this.querySelector('[name=message]').value
+  }
+  if (message.username.length > 0 && message.message.length > 0) {
+    if (chatprotocol.length > 6) {
+      // If we are goint to insert the 8th element, make sure to delete first.
+      chatprotocol.delete(0)
+    }
+    // Here we insert a message in the shared chat type.
+    // This will call the observe function (see line 40)
+    // and reflect the change in the DOM
+    chatprotocol.push([message])
+    this.querySelector('[name=message]').value = ''
+  }
+  // Do not send this form!
+  event.preventDefault()
+  return false
+}

examples/codemirror/index.html

@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html>
+  <head>
+  </head>
+  <body>
+    <div id="codeMirrorContainer"></div>
+
+    <script src="../../y.js"></script>
+    <script src='../../../y-websockets-client/y-websockets-client.js'></script>
+    <script src="../bower_components/codemirror/lib/codemirror.js"></script>
+    <script src="../bower_components/codemirror/mode/javascript/javascript.js"></script>
+    <link rel="stylesheet" href="../bower_components/codemirror/lib/codemirror.css">
+    <style>
+      .CodeMirror {
+        position: fixed;
+        top: 0;
+        left: 0;
+        height: 100%;
+        width: 100%;
+      }
+    </style>
+    <script src="./index.js"></script>
+  </body>
+</html>

examples/codemirror/index.js

@@ -0,0 +1,16 @@
+/* global Y, CodeMirror */
+
+let y = new Y('codemirror-example', {
+  connector: {
+    name: 'websockets-client',
+    url: 'http://127.0.0.1:1234'
+  }
+})
+
+window.yCodeMirror = y
+
+var editor = CodeMirror(document.querySelector('#codeMirrorContainer'), {
+  mode: 'javascript',
+  lineNumbers: true
+})
+y.define('codemirror', Y.Text).bindCodeMirror(editor)

examples/drawing/index.html

@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<html>
+<body>
+  <style>
+    path {
+      fill: none;
+      stroke: blue;
+      stroke-width: 1px;
+      stroke-linejoin: round;
+      stroke-linecap: round;
+    }
+  </style>
+  <button type="button" id="clearDrawingCanvas">Clear Drawing</button>
+  <svg id="drawingCanvas" viewbox="0 0 100 100" width="100%"></svg>
+  <script src="../../y.js"></script>
+  <script src='../../../y-websockets-client/y-websockets-client.js'></script>
+  <script src="../bower_components/d3/d3.min.js"></script>
+  <script src="./index.js"></script>
+</body>
+</html>

examples/drawing/index.js

@@ -0,0 +1,74 @@
+/* globals Y, d3 */
+
+let y = new Y('drawing-example', {
+  connector: {
+    name: 'websockets-client',
+    url: 'http://127.0.0.1:1234'
+  }
+})
+
+window.yDrawing = y
+var drawing = y.define('drawing', Y.Array)
+var renderPath = d3.svg.line()
+  .x(function (d) { return d[0] })
+  .y(function (d) { return d[1] })
+  .interpolate('basic')
+
+var svg = d3.select('#drawingCanvas')
+  .call(d3.behavior.drag()
+    .on('dragstart', dragstart)
+    .on('drag', drag)
+    .on('dragend', dragend))
+
+// create line from a shared array object and update the line when the array changes
+function drawLine (yarray) {
+  var line = svg.append('path').datum(yarray.toArray())
+  line.attr('d', renderPath)
+  yarray.observe(function (event) {
+    line.remove()
+    line = svg.append('path').datum(yarray.toArray())
+    line.attr('d', renderPath)
+  })
+}
+// call drawLine every time an array is appended
+drawing.observe(function (event) {
+  event.removedElements.forEach(function () {
+    // if one is deleted, all will be deleted!!
+    svg.selectAll('path').remove()
+  })
+  event.addedElements.forEach(function (path) {
+    drawLine(path)
+  })
+})
+// draw all existing content
+for (var i = 0; i < drawing.length; i++) {
+  drawLine(drawing.get(i))
+}
+
+// clear canvas on request
+document.querySelector('#clearDrawingCanvas').onclick = function () {
+  drawing.delete(0, drawing.length)
+}
+
+var sharedLine = null
+function dragstart () {
+  drawing.insert(drawing.length, [Y.Array])
+  sharedLine = drawing.get(drawing.length - 1)
+}
+
+// After one dragged event is recognized, we ignore them for 33ms.
+var ignoreDrag = null
+function drag () {
+  if (sharedLine != null && ignoreDrag == null) {
+    ignoreDrag = window.setTimeout(function () {
+      ignoreDrag = null
+    }, 10)
+    sharedLine.push([d3.mouse(this)])
+  }
+}
+
+function dragend () {
+  sharedLine = null
+  window.clearTimeout(ignoreDrag)
+  ignoreDrag = null
+}

examples/html-editor-drawing-hook/index.html

@@ -0,0 +1,36 @@
+<!DOCTYPE html>
+<html>
+</head>
+  <script src="../../y.js"></script>
+  <script src='../../../y-websockets-client/y-websockets-client.js'></script>
+  <script src="../bower_components/d3/d3.min.js"></script>
+  <script src="./index.js"></script>
+  <style>
+    magic-drawing .drawingCanvas path {
+      fill: none;
+      stroke: blue;
+      stroke-width: 2px;
+      stroke-linejoin: round;
+      stroke-linecap: round;
+    }
+    magic-drawing .drawingCanvas {
+      width: 500px;
+      height: 500px;
+      cursor: default;
+      padding:1px;
+      border:1px solid #021a40;
+    }
+    magic-drawing .clearDrawingButton {
+      position: absolute;
+      top: 0;
+      left: 0;
+    }
+    magic-drawing {
+      position: relative;
+      display: block;
+    }
+  </style>
+</head>
+<body contenteditable="true">
+</body>
+</html>

examples/html-editor-drawing-hook/index.js

@@ -0,0 +1,134 @@
+/* global Y, d3 */
+
+const hooks = {
+  'magic-drawing': {
+    fillType: function (dom, type) {
+      initDrawingBindings(type, dom)
+    },
+    createDom: function (type) {
+      const dom = document.createElement('magic-drawing')
+      initDrawingBindings(type, dom)
+      return dom
+    }
+  }
+}
+
+window.onload = function () {
+  window.domBinding = new Y.DomBinding(window.yXmlType, document.body, { hooks })
+}
+
+window.addMagicDrawing = function addMagicDrawing () {
+  let mt = document.createElement('magic-drawing')
+  mt.setAttribute('data-yjs-hook', 'magic-drawing')
+  document.body.append(mt)
+}
+
+var renderPath = d3.svg.line()
+  .x(function (d) { return d[0] })
+  .y(function (d) { return d[1] })
+  .interpolate('basic')
+
+function initDrawingBindings (type, dom) {
+  dom.contentEditable = 'false'
+  dom.setAttribute('data-yjs-hook', 'magic-drawing')
+  var drawing = type.get('drawing')
+  if (drawing === undefined) {
+    drawing = type.set('drawing', new Y.Array())
+  }
+  var canvas = dom.querySelector('.drawingCanvas')
+  if (canvas == null) {
+    canvas = document.createElementNS('http://www.w3.org/2000/svg', 'svg')
+    canvas.setAttribute('class', 'drawingCanvas')
+    canvas.setAttribute('viewbox', '0 0 100 100')
+    dom.insertBefore(canvas, null)
+  }
+  var clearDrawingButton = dom.querySelector('.clearDrawingButton')
+  if (clearDrawingButton == null) {
+    clearDrawingButton = document.createElement('button')
+    clearDrawingButton.setAttribute('type', 'button')
+    clearDrawingButton.setAttribute('class', 'clearDrawingButton')
+    clearDrawingButton.innerText = 'Clear Drawing'
+    dom.insertBefore(clearDrawingButton, null)
+  }
+  var svg = d3.select(canvas)
+    .call(d3.behavior.drag()
+      .on('dragstart', dragstart)
+      .on('drag', drag)
+      .on('dragend', dragend))
+  // create line from a shared array object and update the line when the array changes
+  function drawLine (yarray, svg) {
+    var line = svg.append('path').datum(yarray.toArray())
+    line.attr('d', renderPath)
+    yarray.observe(function (event) {
+      line.remove()
+      line = svg.append('path').datum(yarray.toArray())
+      line.attr('d', renderPath)
+    })
+  }
+  // call drawLine every time an array is appended
+  drawing.observe(function (event) {
+    event.removedElements.forEach(function () {
+      // if one is deleted, all will be deleted!!
+      svg.selectAll('path').remove()
+    })
+    event.addedElements.forEach(function (path) {
+      drawLine(path, svg)
+    })
+  })
+  // draw all existing content
+  for (var i = 0; i < drawing.length; i++) {
+    drawLine(drawing.get(i), svg)
+  }
+
+  // clear canvas on request
+  clearDrawingButton.onclick = function () {
+    drawing.delete(0, drawing.length)
+  }
+
+  var sharedLine = null
+  function dragstart () {
+    drawing.insert(drawing.length, [Y.Array])
+    sharedLine = drawing.get(drawing.length - 1)
+  }
+
+  // After one dragged event is recognized, we ignore them for 33ms.
+  var ignoreDrag = null
+  function drag () {
+    if (sharedLine != null && ignoreDrag == null) {
+      ignoreDrag = window.setTimeout(function () {
+        ignoreDrag = null
+      }, 10)
+      sharedLine.push([d3.mouse(this)])
+    }
+  }
+
+  function dragend () {
+    sharedLine = null
+    window.clearTimeout(ignoreDrag)
+    ignoreDrag = null
+  }
+}
+
+let y = new Y('html-editor-drawing-hook-example', {
+  connector: {
+    name: 'websockets-client',
+    url: 'http://127.0.0.1:1234'
+  }
+})
+
+window.yXml = y
+window.yXmlType = y.define('xml', Y.XmlFragment)
+window.undoManager = new Y.utils.UndoManager(window.yXmlType, {
+  captureTimeout: 500
+})
+
+document.onkeydown = function interceptUndoRedo (e) {
+  if (e.keyCode === 90 && e.metaKey) {
+    if (!e.shiftKey) {
+      window.undoManager.undo()
+    } else {
+      window.undoManager.redo()
+    }
+    e.preventDefault()
+  }
+}

examples/html-editor/index.html

@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html>
+</head>
+  <script src="./index.mjs" type="module"></script>
+</head>
+<body>
+    <label for="room">Room: </label>
+    <input type="text" id="room" name="room">
+    <div id="content" contenteditable style="position:absolute;top:35px;left:0;right:0;bottom:0;outline: 0px solid transparent;"></div>
+</body>
+</html>

examples/html-editor/index.mjs

@@ -0,0 +1,77 @@
+
+import YWebsocketsConnector from '../../src/Connectors/WebsocketsConnector/WebsocketsConnector.mjs'
+import Y from '../../src/Y.mjs'
+import DomBinding from '../../src/Bindings/DomBinding/DomBinding.mjs'
+import UndoManager from '../../src/Util/UndoManager.mjs'
+import YXmlFragment from '../../src/Types/YXml/YXmlFragment.mjs'
+import YXmlText from '../../src/Types/YXml/YXmlText.mjs'
+import YXmlElement from '../../src/Types/YXml/YXmlElement.mjs'
+import YIndexdDBPersistence from '../../src/Persistences/IndexedDBPersistence.mjs'
+
+const connector = new YWebsocketsConnector()
+const persistence = new YIndexdDBPersistence()
+
+const roomInput = document.querySelector('#room')
+
+let currentRoomName = null
+let y = null
+let domBinding = null
+
+function setRoomName (roomName) {
+  if (currentRoomName !== roomName) {
+    console.log(`change room: "${roomName}"`)
+    roomInput.value = roomName
+    currentRoomName = roomName
+    location.hash = '#' + roomName
+    if (y !== null) {
+      domBinding.destroy()
+    }
+
+    const room = connector._rooms.get(roomName)
+    if (room !== undefined) {
+      y = room.y
+    } else {
+      y = new Y(roomName, null, null, { gc: true })
+      persistence.connectY(roomName, y).then(() => {
+        // connect after persisted content was applied to y
+        // If we don't wait for persistence, the other peer will send all data, waisting
+        // network bandwidth..
+        connector.connectY(roomName, y)
+      })
+      window.y = y
+    }
+
+    window.y = y
+    window.yXmlType = y.define('xml', YXmlFragment)
+
+    domBinding = new DomBinding(window.yXmlType, document.querySelector('#content'), { scrollingElement: document.scrollingElement })
+  }
+}
+window.setRoomName = setRoomName
+
+window.createRooms = function (i = 0) {
+  setInterval(function () {
+    setRoomName(i + '')
+    i++
+    const nodes = []
+    for (let j = 0; j < 100; j++) {
+      const node = new YXmlElement('p')
+      node.insert(0, [new YXmlText(`This is the ${i}th paragraph of room ${i}`)])
+      nodes.push(node)
+    }
+    y.share.xml.insert(0, nodes)
+  }, 100)
+}
+
+connector.syncPersistence(persistence)
+
+window.connector = connector
+window.persistence = persistence
+
+window.onload = function () {
+  setRoomName((location.hash || '#default').slice(1))
+  roomInput.addEventListener('input', e => {
+    const roomName = e.target.value
+    setRoomName(roomName)
+  })
+}

examples/indexeddb/index.html

@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html>
+  <head>
+  </head>
+  <body>
+    <div id="codeMirrorContainer"></div>
+    <script src="../bower_components/codemirror/lib/codemirror.js"></script>
+    <script src="../bower_components/codemirror/mode/javascript/javascript.js"></script>
+    <link rel="stylesheet" href="../bower_components/codemirror/lib/codemirror.css">
+    <style>
+      .CodeMirror {
+        position: fixed;
+        top: 0;
+        left: 0;
+        height: 100%;
+        width: 100%;
+      }
+    </style>
+    <script src="../../y.js"></script>
+    <script src='../../../y-websockets-client/y-websockets-client.js'></script>
+    <script src='../../../y-indexeddb/y-indexeddb.js'></script>
+    <script src="./index.js"></script>
+  </body>
+</html>

examples/indexeddb/index.js

@@ -0,0 +1,19 @@
+/* global Y, CodeMirror */
+
+const persistence = new Y.IndexedDB()
+const connector = {
+  connector: {
+    name: 'websockets-client',
+    room: 'codemirror-example'
+  }
+}
+
+const y = new Y('codemirror-example', connector, persistence)
+window.yCodeMirror = y
+
+var editor = CodeMirror(document.querySelector('#codeMirrorContainer'), {
+  mode: 'javascript',
+  lineNumbers: true
+})
+
+y.define('codemirror', Y.Text).bindCodeMirror(editor)

examples/infiniteyjs/index.html

@@ -0,0 +1,55 @@
+<!DOCTYPE html>
+<html>
+<body>
+  <style>
+    .wrapper {
+      display: grid;
+      grid-template-columns: repeat(3, 1fr);
+      grid-gap: 7px;
+    }
+    .one {
+      grid-column: 1 ;
+    }
+    .two {
+      grid-column: 2;
+    }
+    .three {
+      grid-column: 3;
+    }
+    textarea {
+      width: calc(100% - 10px)
+    }
+    .editor-container {
+      background-color: #4caf50;
+      padding: 4px 5px 10px 5px;
+      border-radius: 11px;
+    }
+    .editor-container[disconnected] {
+      background-color: red;
+    }
+    .disconnected-info {
+      display: none;
+    }
+    .editor-container[disconnected] .disconnected-info {
+      display: inline;
+    }
+  </style>
+  <div class="wrapper">
+    <div id="container1" class="one editor-container">
+      <h1>Server 1 <span class="disconnected-info">(disconnected)</span></h1>
+      <textarea id="textarea1" rows=40 autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false"></textarea>
+    </div>
+    <div id="container2" class="two editor-container">
+      <h1>Server 2 <span class="disconnected-info">(disconnected)</span></h1>
+      <textarea id="textarea2" rows=40 autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false"></textarea>
+    </div>
+    <div id="container3" class="three editor-container">
+      <h1>Server 3 <span class="disconnected-info">(disconnected)</span></h1>
+      <textarea id="textarea3" rows=40 autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false"></textarea>
+    </div>
+  </div>
+  <script src="../../y.js"></script>
+  <script src='../../../y-websockets-client/y-websockets-client.js'></script>
+  <script src="./index.js"></script>
+</body>
+</html>

examples/infiniteyjs/index.js

@@ -0,0 +1,38 @@
+/* global Y */
+
+function bindYjsInstance (y, suffix) {
+  y.define('textarea', Y.Text).bind(document.getElementById('textarea' + suffix))
+  y.connector.socket.on('connection', function () {
+    document.getElementById('container' + suffix).removeAttribute('disconnected')
+  })
+  y.connector.socket.on('disconnect', function () {
+    document.getElementById('container' + suffix).setAttribute('disconnected', true)
+  })
+}
+
+let y1 = new Y('infinite-example', {
+  connector: {
+    name: 'websockets-client',
+    url: 'http://127.0.0.1:1234'
+  }
+})
+window.y1 = y1
+bindYjsInstance(y1, '1')
+
+let y2 = new Y('infinite-example', {
+  connector: {
+    name: 'websockets-client',
+    url: 'http://127.0.0.1:1234'
+  }
+})
+window.y2 = y2
+bindYjsInstance(y2, '2')
+
+let y3 = new Y('infinite-example', {
+  connector: {
+    name: 'websockets-client',
+    url: 'http://127.0.0.1:1234'
+  }
+})
+window.y3 = y3
+bindYjsInstance(y1, '3')

examples/jigsaw/index.html

@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <style type="text/css">
+    .draggable {
+      cursor: move;
+    }
+  </style>
+</head>
+<body>
+  <svg id="puzzle-example" width="100%" viewBox="0 0 800 800">
+    <g>
+      <path d="M 311.76636,154.23389 C 312.14136,171.85693 318.14087,184.97998 336.13843,184.23047 C 354.13647,183.48047 351.88647,180.48096 354.88599,178.98096 C 357.8855,177.48096 368.38452,170.35693 380.00806,169.98193 C 424.61841,168.54297 419.78296,223.6001 382.25757,223.6001 C 377.75806,223.6001 363.51001,219.10107 356.38599,211.97656 C 349.26196,204.85254 310.64185,207.10254 314.76636,236.34863 C 316.34888,247.5708 324.08374,267.90723 324.84595,286.23486 C 325.29321,296.99414 323.17603,307.00635 321.58911,315.6377 C 360.11353,305.4585 367.73462,304.30518 404.00513,312.83936 C 410.37915,314.33887 436.62573,310.21436 421.25269,290.3418 C 405.87964,270.46924 406.25464,248.34717 417.12817,240.84814 C 428.00171,233.34912 446.74976,228.84961 457.99829,234.09912 C 469.24683,239.34814 484.61987,255.84619 475.24585,271.59424 C 465.87231,287.34229 452.74878,290.7168 456.49829,303.84033 C 460.2478,316.96387 479.74536,320.33838 500.74292,321.83789 C 509.70142,322.47803 527.97192,323.28467 542.10864,320.12939 C 549.91821,318.38672 556.92212,315.89502 562.46753,313.56396 C 561.40796,277.80664 560.84888,245.71729 560.3606,241.97314 C 558.85278,230.41455 542.49536,217.28564 525.86499,223.2251 C 520.61548,225.1001 519.86548,231.84912 505.24243,232.59912 C 444.92798,235.69238 462.06958,143.26709 525.86499,180.48096 C 539.52759,188.45068 575.19409,190.7583 570.10913,156.85889 C 567.85962,141.86035 553.98608,102.86523 553.98608,102.86523 C 553.98608,102.86523 477.23755,111.82227 451.99878,91.991699 C 441.50024,83.74292 444.87476,69.494629 449.37427,61.245605 C 453.87378,52.996582 465.12231,46.622559 464.74731,36.123779 C 463.02563,-12.086426 392.96704,-10.902832 396.5061,36.873535 C 397.25562,46.997314 406.62964,52.621582 410.75415,60.495605 C 420.00757,78.161377 405.50024,96.073486 384.50757,99.490723 C 377.36206,100.65381 349.17505,102.65332 320.39429,102.23486 C 319.677,102.22461 318.95923,102.21143 318.24194,102.19775 C 315.08423,120.9751 311.55688,144.39697 311.76636,154.23389 z " style="fill:#f2c569;stroke:#000000" id="path2502"/>
+      <path d="M 500.74292,321.83789 C 479.74536,320.33838 460.2478,316.96387 456.49829,303.84033 C 452.74878,290.7168 465.87231,287.34229 475.24585,271.59424 C 484.61987,255.84619 469.24683,239.34814 457.99829,234.09912 C 446.74976,228.84961 428.00171,233.34912 417.12817,240.84814 C 406.25464,248.34717 405.87964,270.46924 421.25269,290.3418 C 436.62573,310.21436 410.37915,314.33887 404.00513,312.83936 C 367.73462,304.30518 360.11353,305.4585 321.58911,315.6377 C 320.56372,321.21484 319.75854,326.2207 320.01538,330.46191 C 320.76538,342.83545 329.3894,385.95508 327.8894,392.7041 C 326.3894,399.45312 313.64136,418.20117 297.89331,407.32715 C 282.14526,396.45361 276.52075,393.4541 265.27222,394.5791 C 254.02368,395.70361 239.77563,402.07812 239.77563,419.32568 C 239.77563,436.57373 250.27417,449.69727 268.64673,447.82227 C 287.36353,445.9126 317.92163,423.11035 325.63989,452.69678 C 330.1394,469.94434 330.51392,487.19238 330.1394,498.44092 C 329.95825,503.87646 326.09985,518.06592 322.16089,531.28125 C 353.2854,532.73682 386.47095,531.26611 394.2561,529.93701 C 430.30933,523.78174 429.31909,496.09766 412.62866,477.44385 C 406.25464,470.31934 401.75513,455.32129 405.87964,444.82275 C 414.07056,423.97314 458.8064,422.17773 473.37134,438.82324 C 483.86987,450.82178 475.99585,477.44385 468.49683,482.69287 C 453.52222,493.17529 457.22485,516.83008 473.37134,528.06201 C 504.79126,549.91943 572.35913,535.56152 572.35913,535.56152 C 572.35913,535.56152 567.85962,498.06592 567.48462,471.81934 C 567.10962,445.57275 589.60669,450.07227 593.3562,450.07227 C 597.10571,450.07227 604.22974,455.32129 609.47925,459.4458 C 614.72876,463.57031 618.85327,469.94434 630.85181,470.69434 C 677.43726,473.60596 674.58813,420.7373 631.97632,413.32666 C 623.35229,411.82666 614.72876,416.32617 603.10522,424.57519 C 591.48169,432.82422 577.23315,425.32519 570.10913,417.45117 C 566.07788,412.99561 563.8479,360.16406 562.46753,313.56396 C 556.92212,315.89502 549.91821,318.38672 542.10864,320.12939 C 527.97192,323.28467 509.70142,322.47803 500.74292,321.83789 z " style="fill:#f3f3d6;stroke:#000000" id="path2504"/>
+      <path d="M 240.52563,141.86035 C 257.60327,159.6499 243.94507,188.68799 214.65356,190.22949 C 185.09448,191.78516 164.66675,157.17822 190.28589,136.61621 C 200.49585,128.42139 198.05786,114.12158 179.78296,106.98975 C 154.4187,97.091553 90.54419,107.73975 90.54419,107.73975 C 90.54419,107.73975 100.88794,135.11328 101.41772,168.48242 C 101.79272,192.104 68.796875,189.47949 63.172607,186.85498 C 57.54834,184.23047 45.924805,173.73145 37.675781,173.73145 C -14.411865,173.73145 -10.013184,245.84375 39.925537,232.22412 C 48.174316,229.97461 56.42334,220.97559 68.796875,222.47559 C 81.17041,223.9751 87.544434,232.59912 87.544434,246.09766 C 87.544434,252.51709 87.0354,281.24268 86.340576,312.87012 C 119.15894,313.67676 160.60962,314.46582 170.03442,313.58887 C 186.15698,312.08936 195.90601,301.59033 188.40698,293.3418 C 180.90796,285.09277 156.16089,256.59619 179.03296,239.34814 C 201.90503,222.10059 235.65112,231.84912 239.77563,247.22217 C 243.90015,262.59521 240.52563,273.46924 234.90112,279.09326 C 229.27661,284.71777 210.52905,298.96582 221.40259,308.71484 C 232.27661,318.46338 263.77222,330.83691 302.39282,320.71338 C 309.58862,318.82715 315.92114,317.13525 321.58911,315.6377 C 323.17603,307.00635 325.29321,296.99414 324.84595,286.23486 C 324.08374,267.90723 316.34888,247.5708 314.76636,236.34863 C 310.64185,207.10254 349.26196,204.85254 356.38599,211.97656 C 363.51001,219.10107 377.75806,223.6001 382.25757,223.6001 C 419.78296,223.6001 424.61841,168.54297 380.00806,169.98193 C 368.38452,170.35693 357.8855,177.48096 354.88599,178.98096 C 351.88647,180.48096 354.13647,183.48047 336.13843,184.23047 C 318.14087,184.97998 312.14136,171.85693 311.76636,154.23389 C 311.55688,144.39697 315.08423,120.9751 318.24194,102.19775 C 290.37524,101.67725 262.46069,98.968262 254.39868,97.991211 C 233.38013,95.443359 217.17456,117.53662 240.52563,141.86035 z " style="fill:#bebcdb;stroke:#000000" id="path2506"/>
+      <path d="M 325.63989,452.69678 C 317.92163,423.11035 287.36353,445.9126 268.64673,447.82227 C 250.27417,449.69727 239.77563,436.57373 239.77563,419.32568 C 239.77563,402.07812 254.02368,395.70361 265.27222,394.5791 C 276.52075,393.4541 282.14526,396.45361 297.89331,407.32715 C 313.64136,418.20117 326.3894,399.45313 327.8894,392.7041 C 329.3894,385.95508 320.76538,342.83545 320.01538,330.46191 C 319.75855,326.2207 320.56372,321.21484 321.58911,315.6377 C 315.92114,317.13525 309.58862,318.82715 302.39282,320.71338 C 263.77222,330.83691 232.27661,318.46338 221.40259,308.71484 C 210.52905,298.96582 229.27661,284.71777 234.90112,279.09326 C 240.52563,273.46924 243.90015,262.59521 239.77563,247.22217 C 235.65112,231.84912 201.90503,222.10059 179.03296,239.34814 C 156.16089,256.59619 180.90796,285.09277 188.40698,293.3418 C 195.90601,301.59033 186.15698,312.08936 170.03442,313.58887 C 160.60962,314.46582 119.15894,313.67676 86.340576,312.87012 C 85.573975,347.74561 84.581299,386.15088 83.794922,402.07812 C 82.295166,432.44922 109.29175,422.32568 115.66577,420.82568 C 122.04028,419.32568 126.16479,409.57715 143.03735,408.45215 C 185.9231,405.59326 186.09985,466.69629 144.16235,467.69482 C 128.41431,468.06982 113.79126,451.19678 108.16675,447.44727 C 102.54272,443.69775 87.919433,442.94775 83.794922,457.9458 C 82.01709,464.41113 78.118652,481.65137 78.098144,496.18994 C 78.071045,515.38037 82.295166,531.81201 82.295166,531.81201 C 82.295166,531.81201 105.54224,526.5625 149.41187,526.5625 C 193.28149,526.5625 199.65552,547.93506 194.78101,558.80859 C 189.90649,569.68213 181.28296,568.93213 179.40796,583.18066 C 172.7063,634.11133 253.34106,631.08203 249.14917,584.68018 C 247.96948,571.62354 237.16528,571.66699 232.27661,557.68359 C 222.17944,528.80273 244.64966,523.56299 257.39819,524.68799 C 263.59351,525.23437 290.95679,529.73389 320.75757,531.21582 C 321.22437,531.23877 321.69312,531.25928 322.16089,531.28125 C 326.09985,518.06592 329.95825,503.87646 330.1394,498.44092 C 330.51392,487.19238 330.1394,469.94434 325.63989,452.69678 z " style="fill:#d3ea9d;stroke:#000000" id="path2508"/>
+		</g>
+  </svg>
+  <script src="../../y.js"></script>
+  <script src='../../../y-websockets-client/y-websockets-client.js'></script>
+  <script src="../bower_components/d3/d3.js"></script>
+  <script src="./index.js"></script>
+</body>
+</html>

examples/jigsaw/index.js

@@ -0,0 +1,67 @@
+/* global Y, d3 */
+
+let y = new Y('jigsaw-example', {
+  connector: {
+    name: 'websockets-client',
+    url: 'http://127.0.0.1:1234'
+  }
+})
+
+let jigsaw = y.define('jigsaw', Y.Map)
+window.yJigsaw = y
+
+var origin // mouse start position - translation of piece
+var drag = d3.behavior.drag()
+  .on('dragstart', function (params) {
+    // get the translation of the element
+    var translation = d3
+      .select(this)
+      .attr('transform')
+      .slice(10, -1)
+      .split(',')
+      .map(Number)
+    // mouse coordinates
+    var mouse = d3.mouse(this.parentNode)
+    origin = {
+      x: mouse[0] - translation[0],
+      y: mouse[1] - translation[1]
+    }
+  })
+  .on('drag', function () {
+    var mouse = d3.mouse(this.parentNode)
+    var x = mouse[0] - origin.x // =^= mouse - mouse at dragstart + translation at dragstart
+    var y = mouse[1] - origin.y
+    d3.select(this).attr('transform', 'translate(' + x + ',' + y + ')')
+  })
+  .on('dragend', function (piece, i) {
+    // save the current translation of the puzzle piece
+    var mouse = d3.mouse(this.parentNode)
+    var x = mouse[0] - origin.x
+    var y = mouse[1] - origin.y
+    jigsaw.set(piece, {x: x, y: y})
+  })
+
+var data = ['piece1', 'piece2', 'piece3', 'piece4']
+var pieces = d3.select(document.querySelector('#puzzle-example')).selectAll('path').data(data)
+
+pieces
+  .classed('draggable', true)
+  .attr('transform', function (piece) {
+    var translation = piece.get('translation') || {x: 0, y: 0}
+    return 'translate(' + translation.x + ',' + translation.y + ')'
+  }).call(drag)
+
+data.forEach(function (piece) {
+  jigsaw.observe(function () {
+    // whenever a property of a piece changes, update the translation of the pieces
+    pieces
+      .transition()
+      .attr('transform', function (piece) {
+        var translation = piece.get(piece)
+        if (translation == null || typeof translation.x !== 'number' || typeof translation.y !== 'number') {
+          translation = { x: 0, y: 0 }
+        }
+        return 'translate(' + translation.x + ',' + translation.y + ')'
+      })
+  })
+})

examples/monaco/index.html

@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<html>
+  <head>
+  </head>
+  <body>
+    <div id="monacoContainer"></div>
+    <style>
+      #monacoContainer {
+        position: fixed;
+        top: 0;
+        left: 0;
+        height: 100%;
+        width: 100%;
+      }
+    </style>
+    <script src="../../y.js"></script>
+    <script src='../../../y-websockets-client/y-websockets-client.js'></script>
+    <script src="../node_modules/monaco-editor/min/vs/loader.js"></script>
+    <script src="./index.js"></script>
+  </body>
+</html>

examples/monaco/index.js

@@ -0,0 +1,22 @@
+/* global Y, monaco */
+
+require.config({ paths: { 'vs': '../node_modules/monaco-editor/min/vs' } })
+
+let y = new Y('monaco-example', {
+  connector: {
+    name: 'websockets-client',
+    url: 'http://127.0.0.1:1234'
+  }
+})
+
+require(['vs/editor/editor.main'], function () {
+  window.yMonaco = y
+
+  // Create Monaco editor
+  var editor = monaco.editor.create(document.getElementById('monacoContainer'), {
+    language: 'javascript'
+  })
+
+  // Bind to y.share.monaco
+  y.define('monaco', Y.Text).bindMonaco(editor)
+})

examples/notes/index.html

@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<html>
+</head>
+  <script src="./index.mjs" type="module"></script>
+</head>
+<body contenteditable="true">
+</body>
+</html>

examples/notes/index.mjs

@@ -0,0 +1,48 @@
+
+import IndexedDBPersistence from '../../src/Persistences/IndexeddbPersistence.mjs'
+import YWebsocketsConnector from '../../src/Connectors/WebsocketsConnector/WebsocketsConnector.mjs'
+import Y from '../../src/Y.mjs'
+import YXmlFragment from '../../src/Types/YXml/YXmlFragment.mjs'
+
+const yCollection = new YCollection(new YWebsocketsConnector(), new IndexedDBPersistence())
+
+const y = yCollection.getDocument('my-notes')
+
+
+
+
+
+persistence.addConnector(persistence)
+
+const y = new Y()
+await persistence.persistY(y)
+
+
+connector.connectY('html-editor', y)
+persistence.connectY('html-editor', y)
+
+
+
+
+window.connector = connector
+
+window.onload = function () {
+  window.domBinding = new DomBinding(window.yXmlType, document.body, { scrollingElement: document.scrollingElement })
+}
+
+window.y = y
+window.yXmlType = y.define('xml', YXmlFragment)
+window.undoManager = new UndoManager(window.yXmlType, {
+  captureTimeout: 500
+})
+
+document.onkeydown = function interceptUndoRedo (e) {
+  if (e.keyCode === 90 && (e.metaKey || e.ctrlKey)) {
+    if (!e.shiftKey) {
+      window.undoManager.undo()
+    } else {
+      window.undoManager.redo()
+    }
+    e.preventDefault()
+  }
+}

examples/package.json

@@ -0,0 +1,23 @@
+{
+  "name": "examples",
+  "version": "0.0.0",
+  "description": "",
+  "scripts": {
+    "dist": "rollup -c",
+    "watch": "rollup -cw"
+  },
+  "author": "Kevin Jahns",
+  "license": "MIT",
+  "dependencies": {
+    "monaco-editor": "^0.8.3",
+    "rollup": "^0.52.3"
+  },
+  "devDependencies": {
+    "standard": "^10.0.2"
+  },
+  "standard": {
+    "ignore": [
+      "bower_components"
+    ]
+  }
+}

examples/quill-cursors/index.html

@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <!-- Main quill library -->
+  <script src="../../node_modules/quill/dist/quill.min.js"></script>
+  <link href="../../node_modules/quill/dist/quill.snow.css" rel="stylesheet">
+  <!-- Quill cursors module -->
+  <script src="../../node_modules/quill-cursors/dist/quill-cursors.min.js"></script>
+  <link href="../../node_modules/quill-cursors/dist/quill-cursors.css" rel="stylesheet">
+  <!-- Yjs Library and connector -->
+  <script src="../../y.js"></script>
+  <script src='../../../y-websockets-client/y-websockets-client.js'></script>
+</head>
+<body>
+  <div id="quill-container">
+    <div id="quill">
+    </div>
+  </div>
+  <script src="./index.js"></script>
+</body>
+</html>

examples/quill-cursors/index.js

@@ -0,0 +1,78 @@
+/* global Y, Quill, QuillCursors */
+
+Quill.register('modules/cursors', QuillCursors)
+
+let y = new Y('quill-0', {
+  connector: {
+    name: 'websockets-client',
+    url: 'http://127.0.0.1:1234'
+  }
+})
+let users = y.define('users', Y.Array)
+let myUserInfo = new Y.Map()
+myUserInfo.set('name', 'dada')
+myUserInfo.set('color', 'red')
+users.push([myUserInfo])
+
+let 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' }]
+    ],
+    cursors: {
+      hideDelay: 500
+    }
+  },
+  placeholder: 'Compose an epic...',
+  theme: 'snow'  // or 'bubble'
+})
+
+let cursors = quill.getModule('cursors')
+
+function drawCursors () {
+  cursors.clearCursors()
+  users.map((user, userId) => {
+    if (user !== myUserInfo) {
+      let relativeRange = user.get('range')
+      let lastUpdated = new Date(user.get('last updated'))
+      if (lastUpdated != null && new Date() - lastUpdated < 20000 && relativeRange != null) {
+        let start = Y.utils.fromRelativePosition(y, relativeRange.start).offset
+        let end = Y.utils.fromRelativePosition(y, relativeRange.end).offset
+        let range = { index: start, length: end - start }
+        cursors.setCursor(userId + '', range, user.get('name'), user.get('color'))
+      }
+    }
+  })
+}
+
+users.observeDeep(drawCursors)
+drawCursors()
+
+quill.on('selection-change', function (range) {
+  if (range != null) {
+    myUserInfo.set('range', {
+      start: Y.utils.getRelativePosition(yText, range.index),
+      end: Y.utils.getRelativePosition(yText, range.index + range.length)
+    })
+  } else {
+    myUserInfo.delete('range')
+  }
+  myUserInfo.set('last updated', new Date().toString())
+})
+
+let yText = y.define('quill', Y.Text)
+let quillBinding = new Y.QuillBinding(yText, quill)
+
+window.quillBinding = quillBinding
+window.yText = yText
+window.y = y
+window.quill = quill
+window.users = users
+window.cursors = cursors

examples/quill/index.html

@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <!-- Main Quill library -->
+  <script src="../../node_modules/quill/dist/quill.min.js"></script>
+  <link href="../../node_modules/quill/dist/quill.snow.css" rel="stylesheet">
+  <!-- Yjs Library and connector -->
+  <script src="../../y.js"></script>
+  <script src='../../../y-websockets-client/y-websockets-client.js'></script>
+</head>
+<body>
+  <div id="quill-container">
+    <div id="quill">
+    </div>
+  </div>
+  <script src="./index.js"></script>
+</body>
+</html>

examples/quill/index.js

@@ -0,0 +1,33 @@
+/* global Y, Quill */
+
+let y = new Y('quill-cursors-0', {
+  connector: {
+    name: 'websockets-client',
+    url: 'http://127.0.0.1:1234'
+  }
+})
+
+let 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'
+})
+
+let yText = y.define('quill', Y.Text)
+
+let quillBinding = new Y.QuillBinding(yText, quill)
+window.quillBinding = quillBinding
+window.yText = yText
+window.y = y
+window.quill = quill

examples/rollup.config.js

@@ -0,0 +1,29 @@
+import nodeResolve from 'rollup-plugin-node-resolve'
+import commonjs from 'rollup-plugin-commonjs'
+
+var pkg = require('./package.json')
+
+export default {
+  input: 'yjs-dist.mjs',
+  name: 'Y',
+  output: {
+    file: 'yjs-dist.js',
+    format: 'umd'
+  },
+  plugins: [
+    nodeResolve({
+      main: true,
+      module: true,
+      browser: true
+    }),
+    commonjs()
+  ],
+  sourcemap: true,
+  banner: `
+/**
+ * ${pkg.name} - ${pkg.description}
+ * @version v${pkg.version}
+ * @license ${pkg.license}
+ */
+`
+}

examples/serviceworker/index.html

@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <!-- quill does not include dist files! We are using the hosted version instead -->
+  <!--link rel="stylesheet" href="../bower_components/quill/dist/quill.snow.css" /-->
+  <link href="https://cdn.quilljs.com/1.0.4/quill.snow.css" rel="stylesheet">
+  <link href="//cdnjs.cloudflare.com/ajax/libs/KaTeX/0.5.1/katex.min.css" rel="stylesheet">
+  <link href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.2.0/styles/monokai-sublime.min.css" rel="stylesheet">
+  <style>
+    #quill-container {
+      border: 1px solid gray;
+      box-shadow: 0px 0px 10px gray;
+    }
+  </style>
+</head>
+<body>
+  <div id="quill-container">
+    <div id="quill">
+    </div>
+  </div>
+
+  <script src="//cdnjs.cloudflare.com/ajax/libs/KaTeX/0.5.1/katex.min.js" type="text/javascript"></script>
+  <script src="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.2.0/highlight.min.js" type="text/javascript"></script>
+  <script src="https://cdn.quilljs.com/1.0.4/quill.js"></script>
+  <!-- quill does not include dist files! We are using the hosted version instead (see above)
+  <script src="../bower_components/quill/dist/quill.js"></script>
+  -->
+  <script src="../bower_components/yjs/y.js"></script>
+  <script src="./index.js"></script>
+</body>
+</html>

examples/serviceworker/index.js

@@ -0,0 +1,49 @@
+/* global Y, Quill */
+
+// register yjs service worker
+if ('serviceWorker' in navigator) {
+  // Register service worker
+  // it is important to copy yjs-sw-template to the root directory!
+  navigator.serviceWorker.register('./yjs-sw-template.js').then(function (reg) {
+    console.log('Yjs service worker registration succeeded. Scope is ' + reg.scope)
+  }).catch(function (err) {
+    console.error('Yjs service worker registration failed with error ' + err)
+  })
+}
+
+// initialize a shared object. This function call returns a promise!
+Y({
+  db: {
+    name: 'memory'
+  },
+  connector: {
+    name: 'serviceworker',
+    room: 'ServiceWorkerExample2'
+  },
+  sourceDir: '/bower_components',
+  share: {
+    richtext: 'Richtext' // y.share.richtext is of type Y.Richtext
+  }
+}).then(function (y) {
+  window.yServiceWorker = y
+
+  // create quill element
+  window.quill = new Quill('#quill', {
+    modules: {
+      formula: true,
+      syntax: true,
+      toolbar: [
+        [{ size: ['small', false, 'large', 'huge'] }],
+        ['bold', 'italic', 'underline'],
+        [{ color: [] }, { background: [] }],    // Snow theme fills in values
+        [{ script: 'sub' }, { script: 'super' }],
+        ['link', 'image'],
+        ['link', 'code-block'],
+        [{ list: 'ordered' }]
+      ]
+    },
+    theme: 'snow'
+  })
+  // bind quill to richtext type
+  y.share.richtext.bind(window.quill)
+})

examples/serviceworker/yjs-sw-template.js

@@ -0,0 +1,22 @@
+/* eslint-env worker */
+
+// copy and modify this file
+
+self.DBConfig = {
+  name: 'indexeddb'
+}
+self.ConnectorConfig = {
+  name: 'websockets-client',
+  // url: '..',
+  options: {
+    jsonp: false
+  }
+}
+
+importScripts(
+  '/bower_components/yjs/y.js',
+  '/bower_components/y-memory/y-memory.js',
+  '/bower_components/y-indexeddb/y-indexeddb.js',
+  '/bower_components/y-websockets-client/y-websockets-client.js',
+  '/bower_components/y-serviceworker/yjs-sw-include.js'
+)

examples/textarea/index.html

@@ -0,0 +1,9 @@
+<!DOCTYPE html>
+<html>
+<body>
+  <textarea style="width:80%;" rows=40 autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false"></textarea>
+  <script src="../../y.js"></script>
+  <script src='../../../y-websockets-client/y-websockets-client.js'></script>
+  <script src="./index.js"></script>
+</body>
+</html>

examples/textarea/index.js

@@ -0,0 +1,15 @@
+/* global Y */
+
+let y = new Y('textarea-example', {
+  connector: {
+    name: 'websockets-client',
+    url: 'http://127.0.0.1:1234'
+  }
+})
+
+window.yTextarea = y
+
+// bind the textarea to a shared text element
+let type = y.define('textarea', Y.Text)
+let textarea = document.querySelector('textarea')
+window.binding = new Y.TextareaBinding(type, textarea)

examples/xml/index.html

@@ -0,0 +1,43 @@
+<!DOCTYPE html>
+<html>
+</head>
+  <!-- jquery is not required for YXml. It is just here for convenience, and to test batch operations. -->
+  <script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
+  <script src="../../y.js"></script>
+  <script src='../../../y-websockets-client/y-websockets-client.js'></script>
+  <script src="./index.js"></script>
+</head>
+<body>
+  <h1> Shared DOM Example </h1>
+  <p> Use native DOM function or jQuery to manipulate the shared DOM (window.sharedDom). </p>
+  <div class="command">
+    <button type="button">Execute</button>
+    <input type="text" value='$(sharedDom).append("<h3>Appended headline</h3>")' size="40"/>
+  </div>
+  <div class="command">
+    <button type="button">Execute</button>
+    <input type="text" value='$(sharedDom).attr("align","right")' size="40"/>
+  </div>
+  <div class="command">
+    <button type="button">Execute</button>
+    <input type="text" value='$(sharedDom).attr("style","color:blue;")' size="40"/>
+  </div>
+
+  <script>
+    /* global $ */
+    var commands = document.querySelectorAll('.command')
+    Array.prototype.forEach.call(commands, function (command) {
+      var execute = function () {
+        // eslint-disable-next-line no-eval
+        eval(command.querySelector('input').value)
+      }
+      command.querySelector('button').onclick = execute
+      $(command.querySelector('input')).keyup(function (e) {
+        if (e.keyCode === 13) {
+          execute()
+        }
+      })
+    })
+  </script>
+</body>
+</html>

examples/xml/index.js

@@ -0,0 +1,13 @@
+/* global Y */
+
+let y = new Y('xml-example', {
+  connector: {
+    name: 'websockets-client',
+    url: 'http://127.0.0.1:1234'
+  }
+})
+
+window.yXml = y
+// bind xml type to a dom, and put it in body
+window.sharedDom = y.define('xml', Y.XmlElement).toDom()
+document.body.appendChild(window.sharedDom)

funding.json

@@ -1,142 +0,0 @@
-{
-  "version": "v1.0.0",
-  "entity": {
-    "type": "group",
-    "role": "steward",
-    "name": "Kevin Jahns",
-    "email": "kevin.jahns@protonmail.com",
-    "phone": "",
-    "description": "OSS Developer",
-    "webpageUrl": {
-      "url": "https://github.com/yjs"
-    }
-  },
-  "projects": [
-    {
-      "guid": "yjs",
-      "name": "Yjs",
-      "description": "A library for building collaborative applications. #p2p #local-first #CRDT Funding this project will also enable me to maintain the other Yjs-related technologies.",
-      "webpageUrl": {
-        "url": "https://github.com/yjs/yjs"
-      },
-      "repositoryUrl": {
-        "url": "https://github.com/yjs/yjs"
-      },
-      "licenses": [
-        "spdx:MIT"
-      ],
-      "tags": [
-        "collaboration",
-        "p2p",
-        "CRDT",
-        "rich-text",
-        "real-time"
-      ]
-    },
-    {
-      "guid": "Titanic",
-      "name": "Y/Titanic",
-      "description": "A provider for syncing millions of docs efficiently with other peers. This will become the foundation for building real local-first apps with Yjs.",
-      "webpageUrl": {
-        "url": "https://github.com/yjs/titanic",
-        "wellKnown": "https://github.com/yjs/titanic/blob/main/.well-known/funding-manifest-urls"
-      },
-      "repositoryUrl": {
-        "url": "https://github.com/yjs/titanic",
-        "wellKnown": "https://github.com/yjs/titanic/blob/main/.well-known/funding-manifest-urls"
-      },
-      "licenses": [
-        "spdx:MIT"
-      ],
-      "tags": [
-        "privacy",
-        "collaboration",
-        "p2p",
-        "CRDT",
-        "rich-text",
-        "real-time",
-        "web-development"
-      ]
-    }
-  ],
-  "funding": {
-    "channels": [
-      {
-        "guid": "github-sponsors",
-        "type": "payment-provider",
-        "address": "",
-        "description": "For funding of the Yjs project"
-      },
-      {
-        "guid": "y-collective",
-        "type": "payment-provider",
-        "address": "https://opencollective.com/y-collective",
-        "description": "For funding the Y-CRDT - the Rust implementation of Yjs and other listed projects."
-      }
-    ],
-    "plans": [
-      {
-        "guid": "supporter",
-        "status": "active",
-        "name": "Supporter",
-        "description": "",
-        "amount": 0,
-        "currency": "USD",
-        "frequency": "monthly",
-        "channels": [
-          "github-sponsors",
-          "y-collective"
-        ]
-      },
-      {
-        "guid": "titanic-funding",
-        "status": "active",
-        "name": "Titanic Funding",
-        "description": "Fund the next generation of local-first providers.",
-        "amount": 30000,
-        "currency": "USD",
-        "frequency": "one-time",
-        "channels": [
-          "github-sponsors"
-        ]
-      },
-      {
-        "guid": "bronze-sponsor",
-        "status": "active",
-        "name": "Bronze Sponsor",
-        "description": "This is the recommended plan for companies that use Yjs.",
-        "amount": 500,
-        "currency": "USD",
-        "frequency": "monthly",
-        "channels": [
-          "github-sponsors"
-        ]
-      },
-      {
-        "guid": "silver-sponsor",
-        "status": "active",
-        "name": "Silver Sponsor",
-        "description": "This is the recommended plan for large/successfull companies that use Yjs.",
-        "amount": 1000,
-        "currency": "USD",
-        "frequency": "monthly",
-        "channels": [
-          "github-sponsors"
-        ]
-      },
-      {
-        "guid": "gold-sponsor",
-        "status": "active",
-        "name": "Gold Sponsor",
-        "description": "This is the recommended plan for successful companies that build their entire product around Yjs-related technologies.",
-        "amount": 3000,
-        "currency": "USD",
-        "frequency": "monthly",
-        "channels": [
-          "github-sponsors"
-        ]
-      }
-    ],
-    "history": null
-  }
-}

package.json

@@ -1,99 +1,87 @@
 {
   "name": "yjs",
-  "version": "13.6.24",
-  "description": "Shared Editing Library",
-  "main": "./dist/yjs.cjs",
-  "module": "./dist/yjs.mjs",
-  "types": "./dist/src/index.d.ts",
-  "type": "module",
-  "sideEffects": false,
-  "funding": {
-    "type": "GitHub Sponsors ❤",
-    "url": "https://github.com/sponsors/dmonad"
-  },
+  "version": "13.0.0-60",
+  "description": "A framework for real-time p2p shared editing on any data",
+  "main": "./y.node.js",
+  "browser": "./y.js",
+  "module": "./src/y.js",
   "scripts": {
-    "clean": "rm -rf dist docs",
-    "test": "npm run dist && NODE_ENV=development node ./dist/tests.cjs --repetition-time 50",
-    "test-extensive": "npm run lint && npm run dist && node ./dist/tests.cjs --production --repetition-time 10000",
-    "dist": "npm run clean && rollup -c && tsc",
-    "watch": "rollup -wc",
-    "lint": "markdownlint README.md && standard && tsc",
-    "docs": "rm -rf docs; jsdoc --configure ./.jsdoc.json --verbose --readme ./README.md --package ./package.json || true",
-    "serve-docs": "npm run docs && http-server ./docs/",
-    "preversion": "npm run lint && PRODUCTION=1 npm run dist && npm run docs && node ./dist/tests.cjs --repetition-time 1000 && test -e dist/src/index.d.ts && test -e dist/yjs.cjs && test -e dist/yjs.cjs",
-    "debug": "concurrently 'http-server -o test.html' 'npm run watch'",
-    "trace-deopt": "clear && rollup -c  && node --trace-deopt dist/test.cjs",
-    "trace-opt": "clear && rollup -c  && node --trace-opt dist/test.cjs"
+    "start": "node --experimental-modules src/Connectors/WebsocketsConnector/server.mjs",
+    "test": "npm run lint",
+    "debug": "concurrently 'rollup -wc rollup.test.js' 'cutest-serve y.test.js -o'",
+    "lint": "standard src/**/*.mjs test/**/*.mjs tests-lib/**/*.mjs",
+    "docs": "esdoc",
+    "serve-docs": "npm run docs && serve ./docs/",
+    "dist": "rollup -c rollup.browser.js; rollup -c rollup.node.js",
+    "watch": "concurrently 'rollup -wc rollup.browser.js' 'rollup -wc rollup.node.js'",
+    "postversion": "npm run dist",
+    "postpublish": "tag-dist-files --overwrite-existing-tag",
+    "demos": "concurrently 'node --experimental-modules src/Connectors/WebsocketsConnector/server.mjs' 'http-server'"
   },
-  "exports": {
-    ".": {
-      "types": "./dist/src/index.d.ts",
-      "module": "./dist/yjs.mjs",
-      "import": "./dist/yjs.mjs",
-      "require": "./dist/yjs.cjs"
-    },
-    "./src/index.js": "./src/index.js",
-    "./tests/testHelper.js": "./tests/testHelper.js",
-    "./testHelper": "./dist/testHelper.mjs",
-    "./package.json": "./package.json"
+  "now": {
+    "engines": {
+      "node": "10.x.x"
+    }
   },
   "files": [
-    "dist/yjs.*",
-    "dist/src",
-    "src",
-    "tests/testHelper.js",
-    "dist/testHelper.mjs",
-    "sponsor-y.js"
+    "y.*",
+    "src/*",
+    ".esdoc.json",
+    "docs/*"
   ],
-  "dictionaries": {
-    "test": "tests"
-  },
   "standard": {
     "ignore": [
-      "/dist",
-      "/node_modules",
-      "/docs"
+      "/y.js",
+      "/y.js.map"
     ]
   },
   "repository": {
     "type": "git",
-    "url": "https://github.com/yjs/yjs.git"
+    "url": "https://github.com/y-js/yjs.git"
   },
   "keywords": [
     "Yjs",
-    "CRDT",
-    "offline",
-    "offline-first",
-    "shared-editing",
-    "concurrency",
-    "collaboration"
+    "OT",
+    "Collaboration",
+    "Synchronization",
+    "ShareJS",
+    "Coweb",
+    "Concurrency"
   ],
   "author": "Kevin Jahns",
-  "email": "kevin.jahns@protonmail.com",
+  "email": "kevin.jahns@rwth-aachen.de",
   "license": "MIT",
   "bugs": {
-    "url": "https://github.com/yjs/yjs/issues"
-  },
-  "homepage": "https://docs.yjs.dev",
-  "dependencies": {
-    "lib0": "^0.2.99"
+    "url": "https://github.com/y-js/yjs/issues"
   },
+  "homepage": "http://y-js.org",
   "devDependencies": {
-    "@rollup/plugin-commonjs": "^24.0.1",
-    "@rollup/plugin-node-resolve": "^15.0.1",
-    "@types/node": "^18.15.5",
-    "concurrently": "^3.6.1",
-    "http-server": "^0.12.3",
-    "jsdoc": "^3.6.7",
-    "markdownlint-cli": "^0.41.0",
-    "rollup": "^3.20.0",
-    "standard": "^16.0.4",
-    "tui-jsdoc-template": "^1.2.2",
-    "typescript": "^4.9.5",
-    "y-protocols": "^1.0.5"
+    "babel-cli": "^6.24.1",
+    "babel-plugin-external-helpers": "^6.22.0",
+    "babel-plugin-transform-regenerator": "^6.24.1",
+    "babel-plugin-transform-runtime": "^6.23.0",
+    "babel-preset-latest": "^6.24.1",
+    "chance": "^1.0.9",
+    "codemirror": "^5.37.0",
+    "concurrently": "^3.4.0",
+    "cutest": "^0.1.9",
+    "esdoc": "^1.0.4",
+    "esdoc-standard-plugin": "^1.0.0",
+    "quill": "^1.3.5",
+    "quill-cursors": "^1.0.2",
+    "rollup": "^0.58.2",
+    "rollup-plugin-babel": "^2.7.1",
+    "rollup-plugin-commonjs": "^8.0.2",
+    "rollup-plugin-inject": "^2.0.0",
+    "rollup-plugin-multi-entry": "^2.0.1",
+    "rollup-plugin-node-resolve": "^3.0.0",
+    "rollup-plugin-uglify": "^1.0.2",
+    "rollup-regenerator-runtime": "^6.23.1",
+    "rollup-watch": "^3.2.2",
+    "standard": "^11.0.1",
+    "tag-dist-files": "^0.1.6"
   },
-  "engines": {
-    "npm": ">=8.0.0",
-    "node": ">=16.0.0"
+  "dependencies": {
+    "uws": "^10.148.0"
   }
 }

rollup.browser.js

@@ -0,0 +1,46 @@
+import babel from 'rollup-plugin-babel'
+import uglify from 'rollup-plugin-uglify'
+import nodeResolve from 'rollup-plugin-node-resolve'
+import commonjs from 'rollup-plugin-commonjs'
+var pkg = require('./package.json')
+
+export default {
+  input: 'src/Y.dist.mjs',
+  name: 'Y',
+  sourcemap: true,
+  output: {
+    file: 'y.js',
+    format: 'umd'
+  },
+  plugins: [
+    nodeResolve({
+      main: true,
+      module: true,
+      browser: true
+    }),
+    commonjs(),
+    babel(),
+    uglify({
+      mangle: {
+        except: ['YMap', 'Y', 'YArray', 'YText', 'YXmlHook', 'YXmlFragment', 'YXmlElement', 'YXmlEvent', 'YXmlText', 'YEvent', 'YArrayEvent', 'YMapEvent', 'Type', 'Delete', 'ItemJSON', 'ItemString', 'Item']
+      },
+      output: {
+        comments: function (node, comment) {
+          var text = comment.value
+          var type = comment.type
+          if (type === 'comment2') {
+            // multiline comment
+            return /@license/i.test(text)
+          }
+        }
+      }
+    })
+  ],
+  banner: `
+/**
+ * ${pkg.name} - ${pkg.description}
+ * @version v${pkg.version}
+ * @license ${pkg.license}
+ */
+`
+}

rollup.config.js

@@ -1,106 +0,0 @@
-import nodeResolve from '@rollup/plugin-node-resolve'
-import commonjs from '@rollup/plugin-commonjs'
-
-const localImports = process.env.LOCALIMPORTS
-
-const customModules = new Set([
-  'y-websocket',
-  'y-codemirror',
-  'y-ace',
-  'y-textarea',
-  'y-quill',
-  'y-dom',
-  'y-prosemirror'
-])
-/**
- * @type {Set<any>}
- */
-const customLibModules = new Set([
-  'lib0',
-  'y-protocols'
-])
-const debugResolve = {
-  resolveId (importee) {
-    if (importee === 'yjs') {
-      return `${process.cwd()}/src/index.js`
-    }
-    if (localImports) {
-      if (customModules.has(importee.split('/')[0])) {
-        return `${process.cwd()}/../${importee}/src/${importee}.js`
-      }
-      if (customLibModules.has(importee.split('/')[0])) {
-        return `${process.cwd()}/../${importee}`
-      }
-    }
-    return null
-  }
-}
-
-export default [{
-  input: './src/index.js',
-  output: {
-    name: 'Y',
-    file: 'dist/yjs.cjs',
-    format: 'cjs',
-    sourcemap: true
-  },
-  external: id => /^lib0\//.test(id)
-}, {
-  input: './src/index.js',
-  output: {
-    name: 'Y',
-    file: 'dist/yjs.mjs',
-    format: 'esm',
-    sourcemap: true
-  },
-  external: id => /^lib0\//.test(id)
-}, {
-  input: './tests/testHelper.js',
-  output: {
-    name: 'Y',
-    file: 'dist/testHelper.mjs',
-    format: 'esm',
-    sourcemap: true
-  },
-  external: id => /^lib0\//.test(id) || id === 'yjs',
-  plugins: [{
-    resolveId (importee) {
-      if (importee === '../src/index.js') {
-        return 'yjs'
-      }
-      return null
-    }
-  }]
-}, {
-  input: './tests/index.js',
-  output: {
-    name: 'test',
-    file: 'dist/tests.js',
-    format: 'iife',
-    sourcemap: true
-  },
-  plugins: [
-    debugResolve,
-    nodeResolve({
-      mainFields: ['browser', 'module', 'main']
-    }),
-    commonjs()
-  ]
-}, {
-  input: './tests/index.js',
-  output: {
-    name: 'test',
-    file: 'dist/tests.cjs',
-    format: 'cjs',
-    sourcemap: true
-  },
-  plugins: [
-    debugResolve,
-    nodeResolve({
-      mainFields: ['node', 'module', 'main'],
-      exportConditions: ['node', 'module', 'import', 'default']
-    }),
-    commonjs()
-  ],
-  external: id => /^lib0\//.test(id)
-}]

rollup.node.js

@@ -0,0 +1,28 @@
+import nodeResolve from 'rollup-plugin-node-resolve'
+import commonjs from 'rollup-plugin-commonjs'
+var pkg = require('./package.json')
+
+export default {
+  input: 'src/Y.dist.mjs',
+  nameame: 'Y',
+  sourcemap: true,
+  output: {
+    file: 'y.node.js',
+    format: 'cjs'
+  },
+  plugins: [
+    nodeResolve({
+      main: true,
+      module: true,
+      browser: true
+    }),
+    commonjs()
+  ],
+  banner: `
+/**
+ * ${pkg.name} - ${pkg.description}
+ * @version v${pkg.version}
+ * @license ${pkg.license}
+ */
+`
+}

rollup.test.js

@@ -0,0 +1,22 @@
+import nodeResolve from 'rollup-plugin-node-resolve'
+import commonjs from 'rollup-plugin-commonjs'
+import multiEntry from 'rollup-plugin-multi-entry'
+
+export default {
+  input: 'test/index.mjs',
+  name: 'y-tests',
+  sourcemap: true,
+  output: {
+    file: 'y.test.js',
+    format: 'umd'
+  },
+  plugins: [
+    multiEntry(),
+    nodeResolve({
+      main: true,
+      module: true,
+      browser: true
+    }),
+    commonjs()
+  ]
+}

src/Bindings/Binding.mjs

@@ -0,0 +1,47 @@
+
+import { createMutualExclude } from '../Util/mutualExclude.mjs'
+
+/**
+ * Abstract class for bindings.
+ *
+ * A binding handles data binding from a Yjs type to a data object. For example,
+ * you can bind a Quill editor instance to a YText instance with the `QuillBinding` class.
+ *
+ * It is expected that a concrete implementation accepts two parameters
+ * (type and binding target).
+ *
+ * @example
+ *   const quill = new Quill(document.createElement('div'))
+ *   const type = y.define('quill', Y.Text)
+ *   const binding = new Y.QuillBinding(quill, type)
+ *
+ */
+export default class Binding {
+  /**
+   * @param {YType} type Yjs type.
+   * @param {any} target Binding Target.
+   */
+  constructor (type, target) {
+    /**
+     * The Yjs type that is bound to `target`
+     * @type {YType}
+     */
+    this.type = type
+    /**
+     * The target that `type` is bound to.
+     * @type {*}
+     */
+    this.target = target
+    /**
+     * @private
+     */
+    this._mutualExclude = createMutualExclude()
+  }
+  /**
+   * Remove all data observers (both from the type and the target).
+   */
+  destroy () {
+    this.type = null
+    this.target = null
+  }
+}

src/Bindings/CodeMirrorBinding/CodeMirrorBinding.mjs

@@ -0,0 +1,56 @@
+
+import Binding from '../Binding.mjs'
+import simpleDiff from '../../Util/simpleDiff.mjs'
+import { getRelativePosition, fromRelativePosition } from '../../Util/relativePosition.mjs'
+
+function typeObserver () {
+  this._mutualExclude(() => {
+    const textarea = this.target
+    const textType = this.type
+    const relativeStart = getRelativePosition(textType, textarea.selectionStart)
+    const relativeEnd = getRelativePosition(textType, textarea.selectionEnd)
+    textarea.value = textType.toString()
+    const start = fromRelativePosition(textType._y, relativeStart)
+    const end = fromRelativePosition(textType._y, relativeEnd)
+    textarea.setSelectionRange(start, end)
+  })
+}
+
+function domObserver () {
+  this._mutualExclude(() => {
+    let diff = simpleDiff(this.type.toString(), this.target.value)
+    this.type.delete(diff.pos, diff.remove)
+    this.type.insert(diff.pos, diff.insert)
+  })
+}
+
+/**
+ * A binding that binds a YText to a dom textarea.
+ *
+ * This binding is automatically destroyed when its parent is deleted.
+ *
+ * @example
+ *   const textare = document.createElement('textarea')
+ *   const type = y.define('textarea', Y.Text)
+ *   const binding = new Y.QuillBinding(type, textarea)
+ *
+ */
+export default class TextareaBinding extends Binding {
+  constructor (textType, domTextarea) {
+    // Binding handles textType as this.type and domTextarea as this.target
+    super(textType, domTextarea)
+    // set initial value
+    domTextarea.value = textType.toString()
+    // Observers are handled by this class
+    this._typeObserver = typeObserver.bind(this)
+    this._domObserver = domObserver.bind(this)
+    textType.observe(this._typeObserver)
+    domTextarea.addEventListener('input', this._domObserver)
+  }
+  destroy () {
+    // Remove everything that is handled by this class
+    this.type.unobserve(this._typeObserver)
+    this.target.unobserve(this._domObserver)
+    super.destroy()
+  }
+}

src/Bindings/DomBinding/DomBinding.mjs

@@ -0,0 +1,140 @@
+/* global MutationObserver */
+
+import Binding from '../Binding.mjs'
+import { createAssociation, removeAssociation } from './util.mjs'
+import { beforeTransactionSelectionFixer, afterTransactionSelectionFixer } from './selection.mjs'
+import { defaultFilter, applyFilterOnType } from './filter.mjs'
+import typeObserver from './typeObserver.mjs'
+import domObserver from './domObserver.mjs'
+
+/**
+ * A binding that binds the children of a YXmlFragment to a DOM element.
+ *
+ * This binding is automatically destroyed when its parent is deleted.
+ *
+ * @example
+ * const div = document.createElement('div')
+ * const type = y.define('xml', Y.XmlFragment)
+ * const binding = new Y.QuillBinding(type, div)
+ *
+ */
+export default class DomBinding extends Binding {
+  /**
+   * @param {YXmlFragment} type The bind source. This is the ultimate source of
+   *                            truth.
+   * @param {Element} target The bind target. Mirrors the target.
+   * @param {Object} [opts] Optional configurations
+
+   * @param {FilterFunction} [opts.filter=defaultFilter] The filter function to use.
+   */
+  constructor (type, target, opts = {}) {
+    // Binding handles textType as this.type and domTextarea as this.target
+    super(type, target)
+    this.opts = opts
+    opts.document = opts.document || document
+    opts.hooks = opts.hooks || {}
+    this.scrollingElement = opts.scrollingElement || null
+    /**
+     * Maps each DOM element to the type that it is associated with.
+     * @type {Map}
+     */
+    this.domToType = new Map()
+    /**
+     * Maps each YXml type to the DOM element that it is associated with.
+     * @type {Map}
+     */
+    this.typeToDom = new Map()
+    /**
+     * Defines which DOM attributes and elements to filter out.
+     * Also filters remote changes.
+     * @type {FilterFunction}
+     */
+    this.filter = opts.filter || defaultFilter
+    // set initial value
+    target.innerHTML = ''
+    type.forEach(child => {
+      target.insertBefore(child.toDom(opts.document, opts.hooks, this), null)
+    })
+    this._typeObserver = typeObserver.bind(this)
+    this._domObserver = (mutations) => {
+      domObserver.call(this, mutations, opts.document)
+    }
+    type.observeDeep(this._typeObserver)
+    this._mutationObserver = new MutationObserver(this._domObserver)
+    this._mutationObserver.observe(target, {
+      childList: true,
+      attributes: true,
+      characterData: true,
+      subtree: true
+    })
+    const y = type._y
+    // Force flush dom changes before Type changes are applied (they might
+    // modify the dom)
+    this._beforeTransactionHandler = (y, transaction, remote) => {
+      this._domObserver(this._mutationObserver.takeRecords())
+      beforeTransactionSelectionFixer(y, this, transaction, remote)
+    }
+    y.on('beforeTransaction', this._beforeTransactionHandler)
+    this._afterTransactionHandler = (y, transaction, remote) => {
+      afterTransactionSelectionFixer(y, this, transaction, remote)
+      // remove associations
+      // TODO: this could be done more efficiently
+      // e.g. Always delete using the following approach, or removeAssociation
+      // in dom/type-observer..
+      transaction.deletedStructs.forEach(type => {
+        const dom = this.typeToDom.get(type)
+        if (dom !== undefined) {
+          removeAssociation(this, dom, type)
+        }
+      })
+    }
+    y.on('afterTransaction', this._afterTransactionHandler)
+    // Before calling observers, apply dom filter to all changed and new types.
+    this._beforeObserverCallsHandler = (y, transaction) => {
+      // Apply dom filter to new and changed types
+      transaction.changedTypes.forEach((subs, type) => {
+        // Only check attributes. New types are filtered below.
+        if ((subs.size > 1 || (subs.size === 1 && subs.has(null) === false))) {
+          applyFilterOnType(y, this, type)
+        }
+      })
+      transaction.newTypes.forEach(type => {
+        applyFilterOnType(y, this, type)
+      })
+    }
+    y.on('beforeObserverCalls', this._beforeObserverCallsHandler)
+    createAssociation(this, target, type)
+  }
+
+  /**
+   * NOTE: currently does not apply filter to existing elements!
+   * @param {FilterFunction} filter The filter function to use from now on.
+   */
+  setFilter (filter) {
+    this.filter = filter
+    // TODO: apply filter to all elements
+  }
+
+  /**
+   * Remove all properties that are handled by this class.
+   */
+  destroy () {
+    this.domToType = null
+    this.typeToDom = null
+    this.type.unobserveDeep(this._typeObserver)
+    this._mutationObserver.disconnect()
+    const y = this.type._y
+    y.off('beforeTransaction', this._beforeTransactionHandler)
+    y.off('beforeObserverCalls', this._beforeObserverCallsHandler)
+    y.off('afterTransaction', this._afterTransactionHandler)
+    super.destroy()
+  }
+}
+
+  /**
+   * A filter defines which elements and attributes to share.
+   * Return null if the node should be filtered. Otherwise return the Map of
+   * accepted attributes.
+   *
+   * @typedef {function(nodeName: String, attrs: Map): Map|null} FilterFunction
+   */

src/Bindings/DomBinding/domObserver.mjs

@@ -0,0 +1,144 @@
+
+import YXmlHook from '../../Types/YXml/YXmlHook.mjs'
+import {
+  iterateUntilUndeleted,
+  removeAssociation,
+  insertNodeHelper } from './util.mjs'
+import diff from '../../Util/simpleDiff.mjs'
+import YXmlFragment from '../../Types/YXml/YXmlFragment.mjs'
+
+/**
+ * 1. Check if any of the nodes was deleted
+ * 2. Iterate over the children.
+ *    2.1 If a node exists that is not yet bound to a type, insert a new node
+ *    2.2 If _contents.length < dom.childNodes.length, fill the
+ *        rest of _content with childNodes
+ *    2.3 If a node was moved, delete it and
+ *       recreate a new yxml element that is bound to that node.
+ *       You can detect that a node was moved because expectedId
+ *       !== actualId in the list
+ * @private
+ */
+function applyChangesFromDom (binding, dom, yxml, _document) {
+  if (yxml == null || yxml === false || yxml.constructor === YXmlHook) {
+    return
+  }
+  const y = yxml._y
+  const knownChildren = new Set()
+  for (let i = dom.childNodes.length - 1; i >= 0; i--) {
+    const type = binding.domToType.get(dom.childNodes[i])
+    if (type !== undefined && type !== false) {
+      knownChildren.add(type)
+    }
+  }
+  // 1. Check if any of the nodes was deleted
+  yxml.forEach(function (childType) {
+    if (knownChildren.has(childType) === false) {
+      childType._delete(y)
+      removeAssociation(binding, binding.typeToDom.get(childType), childType)
+    }
+  })
+  // 2. iterate
+  const childNodes = dom.childNodes
+  const len = childNodes.length
+  let prevExpectedType = null
+  let expectedType = iterateUntilUndeleted(yxml._start)
+  for (let domCnt = 0; domCnt < len; domCnt++) {
+    const childNode = childNodes[domCnt]
+    const childType = binding.domToType.get(childNode)
+    if (childType !== undefined) {
+      if (childType === false) {
+        // should be ignored or is going to be deleted
+        continue
+      }
+      if (expectedType !== null) {
+        if (expectedType !== childType) {
+          // 2.3 Not expected node
+          if (childType._parent !== yxml) {
+            // child was moved from another parent
+            // childType is going to be deleted by its previous parent
+            removeAssociation(binding, childNode, childType)
+          } else {
+            // child was moved to a different position.
+            removeAssociation(binding, childNode, childType)
+            childType._delete(y)
+          }
+          prevExpectedType = insertNodeHelper(yxml, prevExpectedType, childNode, _document, binding)
+        } else {
+          // Found expected node. Continue.
+          prevExpectedType = expectedType
+          expectedType = iterateUntilUndeleted(expectedType._right)
+        }
+      } else {
+        // 2.2 Fill _content with child nodes
+        prevExpectedType = insertNodeHelper(yxml, prevExpectedType, childNode, _document, binding)
+      }
+    } else {
+      // 2.1 A new node was found
+      prevExpectedType = insertNodeHelper(yxml, prevExpectedType, childNode, _document, binding)
+    }
+  }
+}
+
+/**
+ * @private
+ */
+export default function domObserver (mutations, _document) {
+  this._mutualExclude(() => {
+    this.type._y.transact(() => {
+      let diffChildren = new Set()
+      mutations.forEach(mutation => {
+        const dom = mutation.target
+        const yxml = this.domToType.get(dom)
+        if (yxml === undefined) { // In case yxml is undefined, we double check if we forgot to bind the dom
+          let parent = dom
+          let yParent
+          do {
+            parent = parent.parentElement
+            yParent = this.domToType.get(parent)
+          } while (yParent === undefined && parent !== null)
+          if (yParent !== false && yParent !== undefined && yParent.constructor !== YXmlHook) {
+            diffChildren.add(parent)
+          }
+          return
+        } else if (yxml === false || yxml.constructor === YXmlHook) {
+          // dom element is filtered / a dom hook
+          return
+        }
+        switch (mutation.type) {
+          case 'characterData':
+            var change = diff(yxml.toString(), dom.nodeValue)
+            yxml.delete(change.pos, change.remove)
+            yxml.insert(change.pos, change.insert)
+            break
+          case 'attributes':
+            if (yxml.constructor === YXmlFragment) {
+              break
+            }
+            let name = mutation.attributeName
+            let val = dom.getAttribute(name)
+            // check if filter accepts attribute
+            let attributes = new Map()
+            attributes.set(name, val)
+            if (yxml.constructor !== YXmlFragment && this.filter(dom.nodeName, attributes).size > 0) {
+              if (yxml.getAttribute(name) !== val) {
+                if (val == null) {
+                  yxml.removeAttribute(name)
+                } else {
+                  yxml.setAttribute(name, val)
+                }
+              }
+            }
+            break
+          case 'childList':
+            diffChildren.add(mutation.target)
+            break
+        }
+      })
+      for (let dom of diffChildren) {
+        const yxml = this.domToType.get(dom)
+        applyChangesFromDom(this, dom, yxml, _document)
+      }
+    })
+  })
+}

src/Bindings/DomBinding/domToType.mjs

@@ -0,0 +1,61 @@
+
+import YXmlText from '../../Types/YXml/YXmlText.mjs'
+import YXmlHook from '../../Types/YXml/YXmlHook.mjs'
+import YXmlElement from '../../Types/YXml/YXmlElement.mjs'
+import { createAssociation, domsToTypes } from './util.mjs'
+import { filterDomAttributes, defaultFilter } from './filter.mjs'
+
+/**
+ * Creates a Yjs type (YXml) based on the contents of a DOM Element.
+ *
+ * @param {Element|TextNode} element The DOM Element
+ * @param {?Document} _document Optional. Provide the global document object
+ * @param {Hooks} [hooks = {}] Optional. Set of Yjs Hooks
+ * @param {Filter} [filter=defaultFilter] Optional. Dom element filter
+ * @param {?DomBinding} binding Warning: This property is for internal use only!
+ * @return {YXmlElement | YXmlText}
+ */
+export default function domToType (element, _document = document, hooks = {}, filter = defaultFilter, binding) {
+  let type
+  switch (element.nodeType) {
+    case _document.ELEMENT_NODE:
+      let hookName = null
+      let hook
+      // configure `hookName !== undefined` if element is a hook.
+      if (element.hasAttribute('data-yjs-hook')) {
+        hookName = element.getAttribute('data-yjs-hook')
+        hook = hooks[hookName]
+        if (hook === undefined) {
+          console.error(`Unknown hook "${hookName}". Deleting yjsHook dataset property.`)
+          delete element.removeAttribute('data-yjs-hook')
+          hookName = null
+        }
+      }
+      if (hookName === null) {
+        // Not a hook
+        const attrs = filterDomAttributes(element, filter)
+        if (attrs === null) {
+          type = false
+        } else {
+          type = new YXmlElement(element.nodeName)
+          attrs.forEach((val, key) => {
+            type.setAttribute(key, val)
+          })
+          type.insert(0, domsToTypes(element.childNodes, document, hooks, filter, binding))
+        }
+      } else {
+        // Is a hook
+        type = new YXmlHook(hookName)
+        hook.fillType(element, type)
+      }
+      break
+    case _document.TEXT_NODE:
+      type = new YXmlText()
+      type.insert(0, element.nodeValue)
+      break
+    default:
+      throw new Error('Can\'t transform this node type to a YXml type!')
+  }
+  createAssociation(binding, element, type)
+  return type
+}

src/Bindings/DomBinding/filter.mjs

@@ -0,0 +1,60 @@
+import isParentOf from '../../Util/isParentOf.mjs'
+
+/**
+ * Default filter method (does nothing).
+ *
+ * @param {String} nodeName The nodeName of the element
+ * @param {Map} attrs Map of key-value pairs that are attributes of the node.
+ * @return {Map | null} The allowed attributes or null, if the element should be
+ *                      filtered.
+ */
+export function defaultFilter (nodeName, attrs) {
+  // TODO: implement basic filter that filters out dangerous properties!
+  return attrs
+}
+
+/**
+ *
+ */
+export function filterDomAttributes (dom, filter) {
+  const attrs = new Map()
+  for (let i = dom.attributes.length - 1; i >= 0; i--) {
+    const attr = dom.attributes[i]
+    attrs.set(attr.name, attr.value)
+  }
+  return filter(dom.nodeName, attrs)
+}
+
+/**
+ * Applies a filter on a type.
+ *
+ * @param {Y} y The Yjs instance.
+ * @param {DomBinding} binding The DOM binding instance that has the dom filter.
+ * @param {YXmlElement | YXmlFragment } type The type to apply the filter to.
+ *
+ * @private
+ */
+export function applyFilterOnType (y, binding, type) {
+  if (isParentOf(binding.type, type)) {
+    const nodeName = type.nodeName
+    let attributes = new Map()
+    if (type.getAttributes !== undefined) {
+      let attrs = type.getAttributes()
+      for (let key in attrs) {
+        attributes.set(key, attrs[key])
+      }
+    }
+    const filteredAttributes = binding.filter(nodeName, new Map(attributes))
+    if (filteredAttributes === null) {
+      type._delete(y)
+    } else {
+      // iterate original attributes
+      attributes.forEach((value, key) => {
+        // delete all attributes that are not in filteredAttributes
+        if (filteredAttributes.has(key) === false) {
+          type.removeAttribute(key)
+        }
+      })
+    }
+  }
+}

src/Bindings/DomBinding/selection.mjs

@@ -0,0 +1,84 @@
+/* globals getSelection */
+
+import { getRelativePosition, fromRelativePosition } from '../../Util/relativePosition.mjs'
+
+let browserSelection = null
+let relativeSelection = null
+
+/**
+ * @private
+ */
+export let beforeTransactionSelectionFixer
+if (typeof getSelection !== 'undefined') {
+  beforeTransactionSelectionFixer = function _beforeTransactionSelectionFixer (y, domBinding, transaction, remote) {
+    if (!remote) {
+      return
+    }
+    relativeSelection = { from: null, to: null, fromY: null, toY: null }
+    browserSelection = getSelection()
+    const anchorNode = browserSelection.anchorNode
+    const anchorNodeType = domBinding.domToType.get(anchorNode)
+    if (anchorNode !== null && anchorNodeType !== undefined) {
+      relativeSelection.from = getRelativePosition(anchorNodeType, browserSelection.anchorOffset)
+      relativeSelection.fromY = anchorNodeType._y
+    }
+    const focusNode = browserSelection.focusNode
+    const focusNodeType = domBinding.domToType.get(focusNode)
+    if (focusNode !== null && focusNodeType !== undefined) {
+      relativeSelection.to = getRelativePosition(focusNodeType, browserSelection.focusOffset)
+      relativeSelection.toY = focusNodeType._y
+    }
+  }
+} else {
+  beforeTransactionSelectionFixer = function _fakeBeforeTransactionSelectionFixer () {}
+}
+
+/**
+ * @private
+ */
+export function afterTransactionSelectionFixer (y, domBinding, transaction, remote) {
+  if (relativeSelection === null || !remote) {
+    return
+  }
+  const to = relativeSelection.to
+  const from = relativeSelection.from
+  const fromY = relativeSelection.fromY
+  const toY = relativeSelection.toY
+  let shouldUpdate = false
+  let anchorNode = browserSelection.anchorNode
+  let anchorOffset = browserSelection.anchorOffset
+  let focusNode = browserSelection.focusNode
+  let focusOffset = browserSelection.focusOffset
+  if (from !== null) {
+    let sel = fromRelativePosition(fromY, from)
+    if (sel !== null) {
+      let node = domBinding.typeToDom.get(sel.type)
+      let offset = sel.offset
+      if (node !== anchorNode || offset !== anchorOffset) {
+        anchorNode = node
+        anchorOffset = offset
+        shouldUpdate = true
+      }
+    }
+  }
+  if (to !== null) {
+    let sel = fromRelativePosition(toY, to)
+    if (sel !== null) {
+      let node = domBinding.typeToDom.get(sel.type)
+      let offset = sel.offset
+      if (node !== focusNode || offset !== focusOffset) {
+        focusNode = node
+        focusOffset = offset
+        shouldUpdate = true
+      }
+    }
+  }
+  if (shouldUpdate) {
+    browserSelection.setBaseAndExtent(
+      anchorNode,
+      anchorOffset,
+      focusNode,
+      focusOffset
+    )
+  }
+}

src/Bindings/DomBinding/typeObserver.mjs

@@ -0,0 +1,99 @@
+/* global getSelection */
+
+import YXmlText from '../../Types/YXml/YXmlText.mjs'
+import YXmlHook from '../../Types/YXml/YXmlHook.mjs'
+import { removeDomChildrenUntilElementFound } from './util.mjs'
+
+function findScrollReference (scrollingElement) {
+  if (scrollingElement !== null) {
+    let anchor = getSelection().anchorNode
+    if (anchor == null) {
+      let children = scrollingElement.children // only iterate through non-text nodes
+      for (let i = 0; i < children.length; i++) {
+        const elem = children[i]
+        const rect = elem.getBoundingClientRect()
+        if (rect.top >= 0) {
+          return { elem, top: rect.top }
+        }
+      }
+    } else {
+      if (anchor.nodeType === document.TEXT_NODE) {
+        anchor = anchor.parentElement
+      }
+      const top = anchor.getBoundingClientRect().top
+      return { elem: anchor, top: top }
+    }
+  }
+  return null
+}
+
+function fixScroll (scrollingElement, ref) {
+  if (ref !== null) {
+    const { elem, top } = ref
+    const currentTop = elem.getBoundingClientRect().top
+    const newScroll = scrollingElement.scrollTop + currentTop - top
+    if (newScroll >= 0) {
+      scrollingElement.scrollTop = newScroll
+    }
+  }
+}
+
+/**
+ * @private
+ */
+export default function typeObserver (events) {
+  this._mutualExclude(() => {
+    const scrollRef = findScrollReference(this.scrollingElement)
+    events.forEach(event => {
+      const yxml = event.target
+      const dom = this.typeToDom.get(yxml)
+      if (dom !== undefined && dom !== false) {
+        if (yxml.constructor === YXmlText) {
+          dom.nodeValue = yxml.toString()
+        } else if (event.attributesChanged !== undefined) {
+          // update attributes
+          event.attributesChanged.forEach(attributeName => {
+            const value = yxml.getAttribute(attributeName)
+            if (value === undefined) {
+              dom.removeAttribute(attributeName)
+            } else {
+              dom.setAttribute(attributeName, value)
+            }
+          })
+          /*
+           * TODO: instead of hard-checking the types, it would be best to
+           *       specify the type's features. E.g.
+           *         - _yxmlHasAttributes
+           *         - _yxmlHasChildren
+           *       Furthermore, the features shouldn't be encoded in the types,
+           *       only in the attributes (above)
+           */
+          if (event.childListChanged && yxml.constructor !== YXmlHook) {
+            let currentChild = dom.firstChild
+            yxml.forEach(childType => {
+              const childNode = this.typeToDom.get(childType)
+              switch (childNode) {
+                case undefined:
+                  // Does not exist. Create it.
+                  const node = childType.toDom(this.opts.document, this.opts.hooks, this)
+                  dom.insertBefore(node, currentChild)
+                  break
+                case false:
+                  // nop
+                  break
+                default:
+                  // Is already attached to the dom.
+                  // Find it and remove all dom nodes in-between.
+                  removeDomChildrenUntilElementFound(dom, currentChild, childNode)
+                  currentChild = childNode.nextSibling
+                  break
+              }
+            })
+            removeDomChildrenUntilElementFound(dom, currentChild, null)
+          }
+        }
+      }
+    })
+    fixScroll(this.scrollingElement, scrollRef)
+  })
+}

src/Bindings/DomBinding/util.mjs

@@ -0,0 +1,124 @@
+
+import domToType from './domToType.mjs'
+
+/**
+ * Iterates items until an undeleted item is found.
+ *
+ * @private
+ */
+export function iterateUntilUndeleted (item) {
+  while (item !== null && item._deleted) {
+    item = item._right
+  }
+  return item
+}
+
+/**
+ * Removes an association (the information that a DOM element belongs to a
+ * type).
+ *
+ * @param {DomBinding} domBinding The binding object
+ * @param {Element} dom The dom that is to be associated with type
+ * @param {YXmlElement|YXmlHook} type The type that is to be associated with dom
+ *
+ */
+export function removeAssociation (domBinding, dom, type) {
+  domBinding.domToType.delete(dom)
+  domBinding.typeToDom.delete(type)
+}
+
+/**
+ * Creates an association (the information that a DOM element belongs to a
+ * type).
+ *
+ * @param {DomBinding} domBinding The binding object
+ * @param {Element} dom The dom that is to be associated with type
+ * @param {YXmlElement|YXmlHook} type The type that is to be associated with dom
+ *
+ */
+export function createAssociation (domBinding, dom, type) {
+  if (domBinding !== undefined) {
+    domBinding.domToType.set(dom, type)
+    domBinding.typeToDom.set(type, dom)
+  }
+}
+
+/**
+ * If oldDom is associated with a type, associate newDom with the type and
+ * forget about oldDom. If oldDom is not associated with any type, nothing happens.
+ *
+ * @param {DomBinding} domBinding The binding object
+ * @param {Element} oldDom The existing dom
+ * @param {Element} newDom The new dom object
+ */
+export function switchAssociation (domBinding, oldDom, newDom) {
+  if (domBinding !== undefined) {
+    const type = domBinding.domToType.get(oldDom)
+    if (type !== undefined) {
+      removeAssociation(domBinding, oldDom, type)
+      createAssociation(domBinding, newDom, type)
+    }
+  }
+}
+
+/**
+ * Insert Dom Elements after one of the children of this YXmlFragment.
+ * The Dom elements will be bound to a new YXmlElement and inserted at the
+ * specified position.
+ *
+ * @param {YXmlElement} type The type in which to insert DOM elements.
+ * @param {YXmlElement|null} prev The reference node. New YxmlElements are
+ *                           inserted after this node. Set null to insert at
+ *                           the beginning.
+ * @param {Array<Element>} doms The Dom elements to insert.
+ * @param {?Document} _document Optional. Provide the global document object.
+ * @param {DomBinding} binding The dom binding
+ * @return {Array<YXmlElement>} The YxmlElements that are inserted.
+ *
+ * @private
+ */
+export function insertDomElementsAfter (type, prev, doms, _document, binding) {
+  const types = domsToTypes(doms, _document, binding.opts.hooks, binding.filter, binding)
+  return type.insertAfter(prev, types)
+}
+
+export function domsToTypes (doms, _document, hooks, filter, binding) {
+  const types = []
+  for (let dom of doms) {
+    const t = domToType(dom, _document, hooks, filter, binding)
+    if (t !== false) {
+      types.push(t)
+    }
+  }
+  return types
+}
+
+/**
+ * @private
+ */
+export function insertNodeHelper (yxml, prevExpectedNode, child, _document, binding) {
+  let insertedNodes = insertDomElementsAfter(yxml, prevExpectedNode, [child], _document, binding)
+  if (insertedNodes.length > 0) {
+    return insertedNodes[0]
+  } else {
+    return prevExpectedNode
+  }
+}
+
+/**
+ * Remove children until `elem` is found.
+ *
+ * @param {Element} parent The parent of `elem` and `currentChild`.
+ * @param {Element} currentChild Start removing elements with `currentChild`. If
+ *                               `currentChild` is `elem` it won't be removed.
+ * @param {Element|null} elem The elemnt to look for.
+ *
+ * @private
+ */
+export function removeDomChildrenUntilElementFound (parent, currentChild, elem) {
+  while (currentChild !== elem) {
+    const del = currentChild
+    currentChild = currentChild.nextSibling
+    parent.removeChild(del)
+  }
+}

src/Bindings/QuillBinding/QuillBinding.mjs

@@ -0,0 +1,53 @@
+import Binding from '../Binding.mjs'
+
+function typeObserver (event) {
+  const quill = this.target
+  // Force flush Quill changes.
+  quill.update('yjs')
+  this._mutualExclude(function () {
+    // Apply computed delta.
+    quill.updateContents(event.delta, 'yjs')
+    // Force flush Quill changes. Ignore applied changes.
+    quill.update('yjs')
+  })
+}
+
+function quillObserver (delta) {
+  this._mutualExclude(() => {
+    this.type.applyDelta(delta.ops)
+  })
+}
+
+/**
+ * A Binding that binds a YText type to a Quill editor.
+ *
+ * @example
+ * const quill = new Quill(document.createElement('div'))
+ * const type = y.define('quill', Y.Text)
+ * const binding = new Y.QuillBinding(quill, type)
+ * // Now modifications on the DOM will be reflected in the Type, and the other
+ * // way around!
+ */
+export default class QuillBinding extends Binding {
+  /**
+   * @param {YText} textType
+   * @param {Quill} quill
+   */
+  constructor (textType, quill) {
+    // Binding handles textType as this.type and quill as this.target.
+    super(textType, quill)
+    // Set initial value.
+    quill.setContents(textType.toDelta(), 'yjs')
+    // Observers are handled by this class.
+    this._typeObserver = typeObserver.bind(this)
+    this._quillObserver = quillObserver.bind(this)
+    textType.observe(this._typeObserver)
+    quill.on('text-change', this._quillObserver)
+  }
+  destroy () {
+    // Remove everything that is handled by this class.
+    this.type.unobserve(this._typeObserver)
+    this.target.off('text-change', this._quillObserver)
+    super.destroy()
+  }
+}

src/Bindings/TextareaBinding/TextareaBinding.mjs

@@ -0,0 +1,56 @@
+
+import Binding from '../Binding.mjs'
+import simpleDiff from '../../Util/simpleDiff.mjs'
+import { getRelativePosition, fromRelativePosition } from '../../Util/relativePosition.mjs'
+
+function typeObserver () {
+  this._mutualExclude(() => {
+    const textarea = this.target
+    const textType = this.type
+    const relativeStart = getRelativePosition(textType, textarea.selectionStart)
+    const relativeEnd = getRelativePosition(textType, textarea.selectionEnd)
+    textarea.value = textType.toString()
+    const start = fromRelativePosition(textType._y, relativeStart)
+    const end = fromRelativePosition(textType._y, relativeEnd)
+    textarea.setSelectionRange(start, end)
+  })
+}
+
+function domObserver () {
+  this._mutualExclude(() => {
+    let diff = simpleDiff(this.type.toString(), this.target.value)
+    this.type.delete(diff.pos, diff.remove)
+    this.type.insert(diff.pos, diff.insert)
+  })
+}
+
+/**
+ * A binding that binds a YText to a dom textarea.
+ *
+ * This binding is automatically destroyed when its parent is deleted.
+ *
+ * @example
+ *   const textare = document.createElement('textarea')
+ *   const type = y.define('textarea', Y.Text)
+ *   const binding = new Y.QuillBinding(type, textarea)
+ *
+ */
+export default class TextareaBinding extends Binding {
+  constructor (textType, domTextarea) {
+    // Binding handles textType as this.type and domTextarea as this.target
+    super(textType, domTextarea)
+    // set initial value
+    domTextarea.value = textType.toString()
+    // Observers are handled by this class
+    this._typeObserver = typeObserver.bind(this)
+    this._domObserver = domObserver.bind(this)
+    textType.observe(this._typeObserver)
+    domTextarea.addEventListener('input', this._domObserver)
+  }
+  destroy () {
+    // Remove everything that is handled by this class
+    this.type.unobserve(this._typeObserver)
+    this.target.unobserve(this._domObserver)
+    super.destroy()
+  }
+}

src/Connector.mjs

@@ -0,0 +1,297 @@
+import BinaryEncoder from './Util/Binary/Encoder.mjs'
+import BinaryDecoder from './Util/Binary/Decoder.mjs'
+
+import { sendSyncStep1, readSyncStep1 } from './MessageHandler/syncStep1.mjs'
+import { readSyncStep2 } from './MessageHandler/syncStep2.mjs'
+import { integrateRemoteStructs } from './MessageHandler/integrateRemoteStructs.mjs'
+
+import debug from 'debug'
+
+// TODO: rename Connector
+
+export default class AbstractConnector {
+  constructor (y, opts) {
+    this.y = y
+    this.opts = opts
+    if (opts.role == null || opts.role === 'master') {
+      this.role = 'master'
+    } else if (opts.role === 'slave') {
+      this.role = 'slave'
+    } else {
+      throw new Error("Role must be either 'master' or 'slave'!")
+    }
+    this.log = debug('y:connector')
+    this.logMessage = debug('y:connector-message')
+    this._forwardAppliedStructs = opts.forwardAppliedOperations || false // TODO: rename
+    this.role = opts.role
+    this.connections = new Map()
+    this.isSynced = false
+    this.userEventListeners = []
+    this.whenSyncedListeners = []
+    this.currentSyncTarget = null
+    this.debug = opts.debug === true
+    this.broadcastBuffer = new BinaryEncoder()
+    this.broadcastBufferSize = 0
+    this.protocolVersion = 11
+    this.authInfo = opts.auth || null
+    this.checkAuth = opts.checkAuth || function () { return Promise.resolve('write') } // default is everyone has write access
+    if (opts.maxBufferLength == null) {
+      this.maxBufferLength = -1
+    } else {
+      this.maxBufferLength = opts.maxBufferLength
+    }
+  }
+
+  reconnect () {
+    this.log('reconnecting..')
+  }
+
+  disconnect () {
+    this.log('discronnecting..')
+    this.connections = new Map()
+    this.isSynced = false
+    this.currentSyncTarget = null
+    this.whenSyncedListeners = []
+    return Promise.resolve()
+  }
+
+  onUserEvent (f) {
+    this.userEventListeners.push(f)
+  }
+
+  removeUserEventListener (f) {
+    this.userEventListeners = this.userEventListeners.filter(g => f !== g)
+  }
+
+  userLeft (user) {
+    if (this.connections.has(user)) {
+      this.log('%s: User left %s', this.y.userID, user)
+      this.connections.delete(user)
+      // check if isSynced event can be sent now
+      this._setSyncedWith(null)
+      for (var f of this.userEventListeners) {
+        f({
+          action: 'userLeft',
+          user: user
+        })
+      }
+    }
+  }
+
+  userJoined (user, role, auth) {
+    if (role == null) {
+      throw new Error('You must specify the role of the joined user!')
+    }
+    if (this.connections.has(user)) {
+      throw new Error('This user already joined!')
+    }
+    this.log('%s: User joined %s', this.y.userID, user)
+    this.connections.set(user, {
+      uid: user,
+      isSynced: false,
+      role: role,
+      processAfterAuth: [],
+      processAfterSync: [],
+      auth: auth || null,
+      receivedSyncStep2: false
+    })
+    let defer = {}
+    defer.promise = new Promise(function (resolve) { defer.resolve = resolve })
+    this.connections.get(user).syncStep2 = defer
+    for (var f of this.userEventListeners) {
+      f({
+        action: 'userJoined',
+        user: user,
+        role: role
+      })
+    }
+    this._syncWithUser(user)
+  }
+
+  // Execute a function _when_ we are connected.
+  // If not connected, wait until connected
+  whenSynced (f) {
+    if (this.isSynced) {
+      f()
+    } else {
+      this.whenSyncedListeners.push(f)
+    }
+  }
+
+  _syncWithUser (userID) {
+    if (this.role === 'slave') {
+      return // "The current sync has not finished or this is controlled by a master!"
+    }
+    sendSyncStep1(this, userID)
+  }
+
+  _fireIsSyncedListeners () {
+    if (!this.isSynced) {
+      this.isSynced = true
+      // It is safer to remove this!
+      // call whensynced listeners
+      for (var f of this.whenSyncedListeners) {
+        f()
+      }
+      this.whenSyncedListeners = []
+      this.y._setContentReady()
+      this.y.emit('synced')
+    }
+  }
+
+  send (uid, buffer) {
+    const y = this.y
+    if (!(buffer instanceof ArrayBuffer || buffer instanceof Uint8Array)) {
+      throw new Error('Expected Message to be an ArrayBuffer or Uint8Array - don\'t use this method to send custom messages')
+    }
+    this.log('User%s to User%s: Send \'%y\'', y.userID, uid, buffer)
+    this.logMessage('User%s to User%s: Send %Y', y.userID, uid, [y, buffer])
+  }
+
+  broadcast (buffer) {
+    const y = this.y
+    if (!(buffer instanceof ArrayBuffer || buffer instanceof Uint8Array)) {
+      throw new Error('Expected Message to be an ArrayBuffer or Uint8Array - don\'t use this method to send custom messages')
+    }
+    this.log('User%s: Broadcast \'%y\'', y.userID, buffer)
+    this.logMessage('User%s: Broadcast: %Y', y.userID, [y, buffer])
+  }
+
+  /*
+    Buffer operations, and broadcast them when ready.
+  */
+  broadcastStruct (struct) {
+    const firstContent = this.broadcastBuffer.length === 0
+    if (firstContent) {
+      this.broadcastBuffer.writeVarString(this.y.room)
+      this.broadcastBuffer.writeVarString('update')
+      this.broadcastBufferSize = 0
+      this.broadcastBufferSizePos = this.broadcastBuffer.pos
+      this.broadcastBuffer.writeUint32(0)
+    }
+    this.broadcastBufferSize++
+    struct._toBinary(this.broadcastBuffer)
+    if (this.maxBufferLength > 0 && this.broadcastBuffer.length > this.maxBufferLength) {
+      // it is necessary to send the buffer now
+      // cache the buffer and check if server is responsive
+      const buffer = this.broadcastBuffer
+      buffer.setUint32(this.broadcastBufferSizePos, this.broadcastBufferSize)
+      this.broadcastBuffer = new BinaryEncoder()
+      this.whenRemoteResponsive().then(() => {
+        this.broadcast(buffer.createBuffer())
+      })
+    } else if (firstContent) {
+      // send the buffer when all transactions are finished
+      // (or buffer exceeds maxBufferLength)
+      setTimeout(() => {
+        if (this.broadcastBuffer.length > 0) {
+          const buffer = this.broadcastBuffer
+          buffer.setUint32(this.broadcastBufferSizePos, this.broadcastBufferSize)
+          this.broadcast(buffer.createBuffer())
+          this.broadcastBuffer = new BinaryEncoder()
+        }
+      }, 0)
+    }
+  }
+
+  /*
+   * Somehow check the responsiveness of the remote clients/server
+   * Default behavior:
+   *   Wait 100ms before broadcasting the next batch of operations
+   *
+   * Only used when maxBufferLength is set
+   *
+   */
+  whenRemoteResponsive () {
+    return new Promise(function (resolve) {
+      setTimeout(resolve, 100)
+    })
+  }
+
+  /*
+    You received a raw message, and you know that it is intended for Yjs. Then call this function.
+  */
+  receiveMessage (sender, buffer, skipAuth) {
+    const y = this.y
+    const userID = y.userID
+    skipAuth = skipAuth || false
+    if (!(buffer instanceof ArrayBuffer || buffer instanceof Uint8Array)) {
+      return Promise.reject(new Error('Expected Message to be an ArrayBuffer or Uint8Array!'))
+    }
+    if (sender === userID) {
+      return Promise.resolve()
+    }
+    let decoder = new BinaryDecoder(buffer)
+    let encoder = new BinaryEncoder()
+    let roomname = decoder.readVarString() // read room name
+    encoder.writeVarString(roomname)
+    let messageType = decoder.readVarString()
+    let senderConn = this.connections.get(sender)
+    this.log('User%s from User%s: Receive \'%s\'', userID, sender, messageType)
+    this.logMessage('User%s from User%s: Receive %Y', userID, sender, [y, buffer])
+    if (senderConn == null && !skipAuth) {
+      throw new Error('Received message from unknown peer!')
+    }
+    if (messageType === 'sync step 1' || messageType === 'sync step 2') {
+      let auth = decoder.readVarUint()
+      if (senderConn.auth == null) {
+        senderConn.processAfterAuth.push([messageType, senderConn, decoder, encoder, sender])
+        // check auth
+        return this.checkAuth(auth, y, sender).then(authPermissions => {
+          if (senderConn.auth == null) {
+            senderConn.auth = authPermissions
+            y.emit('userAuthenticated', {
+              user: senderConn.uid,
+              auth: authPermissions
+            })
+          }
+          let messages = senderConn.processAfterAuth
+          senderConn.processAfterAuth = []
+
+          messages.forEach(m =>
+            this.computeMessage(m[0], m[1], m[2], m[3], m[4])
+          )
+        })
+      }
+    }
+    if ((skipAuth || senderConn.auth != null) && (messageType !== 'update' || senderConn.isSynced)) {
+      this.computeMessage(messageType, senderConn, decoder, encoder, sender, skipAuth)
+    } else {
+      senderConn.processAfterSync.push([messageType, senderConn, decoder, encoder, sender, false])
+    }
+  }
+
+  computeMessage (messageType, senderConn, decoder, encoder, sender, skipAuth) {
+    if (messageType === 'sync step 1' && (senderConn.auth === 'write' || senderConn.auth === 'read')) {
+      // cannot wait for sync step 1 to finish, because we may wait for sync step 2 in sync step 1 (->lock)
+      readSyncStep1(decoder, encoder, this.y, senderConn, sender)
+    } else {
+      const y = this.y
+      y.transact(function () {
+        if (messageType === 'sync step 2' && senderConn.auth === 'write') {
+          readSyncStep2(decoder, encoder, y, senderConn, sender)
+        } else if (messageType === 'update' && (skipAuth || senderConn.auth === 'write')) {
+          integrateRemoteStructs(y, decoder)
+        } else {
+          throw new Error('Unable to receive message')
+        }
+      }, true)
+    }
+  }
+
+  _setSyncedWith (user) {
+    if (user != null) {
+      const userConn = this.connections.get(user)
+      userConn.isSynced = true
+      const messages = userConn.processAfterSync
+      userConn.processAfterSync = []
+      messages.forEach(m => {
+        this.computeMessage(m[0], m[1], m[2], m[3], m[4])
+      })
+    }
+    const conns = Array.from(this.connections.values())
+    if (conns.length > 0 && conns.every(u => u.isSynced)) {
+      this._fireIsSyncedListeners()
+    }
+  }
+}

src/Connectors/WebsocketsConnector/WebsocketsConnector.mjs

@@ -0,0 +1,140 @@
+import BinaryEncoder from '../../Util/Binary/Encoder.mjs'
+/* global WebSocket */
+import NamedEventHandler from '../../Util/NamedEventHandler.mjs'
+import decodeMessage, { messageSS, messageSubscribe, messageStructs } from './decodeMessage.mjs'
+import { createMutualExclude } from '../../Util/mutualExclude.mjs'
+import { messageCheckUpdateCounter } from './decodeMessage.mjs'
+
+export const STATE_DISCONNECTED = 0 
+export const STATE_CONNECTED = 1
+
+export default class WebsocketsConnector extends NamedEventHandler {
+  constructor (url = 'ws://localhost:1234') {
+    super()
+    this.url = url
+    this._state = STATE_DISCONNECTED
+    this._socket = null
+    this._rooms = new Map()
+    this._connectToServer = true
+    this._reconnectTimeout = 300
+    this._mutualExclude = createMutualExclude()
+    this._persistence = null
+    this.connect()
+  }
+
+  getRoom (roomName) {
+    return this._rooms.get(roomName) || { y: null, roomName, localUpdateCounter: 1 }
+  }
+
+  syncPersistence (persistence) {
+    this._persistence = persistence
+    if (this._state === STATE_CONNECTED) {
+      persistence.getAllDocuments().then(docs => {
+        const encoder = new BinaryEncoder()
+        docs.forEach(doc => {
+          messageCheckUpdateCounter(doc.roomName, encoder, doc.remoteUpdateCounter)
+        });
+        this.send(encoder)
+      })
+    }
+  }
+
+  connectY (roomName, y) {
+    let room = this._rooms.get(roomName)
+    if (room !== undefined) {
+      throw new Error('Room is already taken! There can be only one Yjs instance per roomName!')
+    }
+    this._rooms.set(roomName, {
+      roomName,
+      y,
+      localUpdateCounter: 1
+    })
+    y.on('afterTransaction', (y, transaction) => {
+      this._mutualExclude(() => {
+        if (transaction.encodedStructsLen > 0) {
+          const encoder = new BinaryEncoder()
+          const room = this._rooms.get(roomName)
+          messageStructs(roomName, y, encoder, transaction.encodedStructs, ++room.localUpdateCounter)
+          this.send(encoder)
+        }
+      })
+    })
+    if (this._state === STATE_CONNECTED) {
+      const encoder = new BinaryEncoder()
+      messageSS(roomName, y, encoder)
+      messageSubscribe(roomName, y, encoder)
+      this.send(encoder)
+    }
+  }
+
+  _setState (state) {
+    this._state = state
+    this.emit('stateChanged', {
+      state: this.state
+    })
+  }
+
+  get state () {
+    return this._state === STATE_DISCONNECTED ? 'disconnected' : 'connected'
+  }
+
+  _onOpen () {
+    this._setState(STATE_CONNECTED)
+    if (this._persistence === null) {
+      const encoder = new BinaryEncoder()
+      for (const [roomName, room] of this._rooms) {
+        const y = room.y
+        messageSS(roomName, y, encoder)
+        messageSubscribe(roomName, y, encoder)
+      }
+      this.send(encoder)
+    } else {
+      this.syncPersistence(this._persistence)
+    }
+  }
+
+  send (encoder) {
+    if (encoder.length > 0 && this._socket.readyState === WebSocket.OPEN) {
+      this._socket.send(encoder.createBuffer())
+    }
+  }
+
+  _onClose () {
+    this._setState(STATE_DISCONNECTED)
+    this._socket = null
+    if (this._connectToServer) {
+      setTimeout(() => {
+        if (this._connectToServer) {
+          this.connect()
+        }
+      }, this._reconnectTimeout)
+      this.connect()
+    }
+  }
+
+  _onMessage (message) {
+    if (message.data.byteLength > 0) {
+      const reply = decodeMessage(this, message.data, null, false, this._persistence)
+      this.send(reply)
+    }
+  }
+
+  disconnect (code = 1000, reason = 'Client manually disconnected') {
+    const socket = this._socket
+    this._connectToServer = false
+    socket.close(code, reason)
+  }
+
+  connect () {
+    if (this._socket === null) {
+      const socket = new WebSocket(this.url)
+      socket.binaryType = 'arraybuffer'
+      this._socket = socket
+      this._connectToServer = true
+      // Connection opened
+      socket.addEventListener('open', this._onOpen.bind(this))
+      socket.addEventListener('close', this._onClose.bind(this))
+      socket.addEventListener('message', this._onMessage.bind(this))
+    }
+  }
+}

src/Connectors/WebsocketsConnector/decodeMessage.mjs

@@ -0,0 +1,159 @@
+import BinaryDecoder from '../../Util/Binary/Decoder.mjs'
+import BinaryEncoder from '../../Util/Binary/Encoder.mjs'
+import { readStateSet, writeStateSet } from '../../MessageHandler/stateSet.mjs'
+import { writeStructs } from '../../MessageHandler/syncStep1.mjs'
+import { writeDeleteSet, readDeleteSet } from '../../MessageHandler/deleteSet.mjs'
+import { integrateRemoteStructs } from '../../MessageHandler/integrateRemoteStructs.mjs'
+
+const CONTENT_GET_SS = 4
+export function messageGetSS (roomName, y, encoder) {
+  encoder.writeVarString(roomName)
+  encoder.writeVarUint(CONTENT_GET_SS)
+}
+
+const CONTENT_SUBSCRIBE = 3
+export function messageSubscribe (roomName, y, encoder) {
+  encoder.writeVarString(roomName)
+  encoder.writeVarUint(CONTENT_SUBSCRIBE)
+}
+
+const CONTENT_SS = 0
+export function messageSS (roomName, y, encoder) {
+  encoder.writeVarString(roomName)
+  encoder.writeVarUint(CONTENT_SS)
+  writeStateSet(y, encoder)
+}
+
+const CONTENT_STRUCTS_DSS = 2
+export function messageStructsDSS (roomName, y, encoder, ss, updateCounter) {
+  encoder.writeVarString(roomName)
+  encoder.writeVarUint(CONTENT_STRUCTS_DSS)
+  encoder.writeVarUint(updateCounter)
+  const structsDS = new BinaryEncoder()
+  writeStructs(y, structsDS, ss)
+  writeDeleteSet(y, structsDS)
+  encoder.writeVarUint(structsDS.length)
+  encoder.writeBinaryEncoder(structsDS)
+}
+
+const CONTENT_STRUCTS = 5
+export function messageStructs (roomName, y, encoder, structsBinaryEncoder, updateCounter) {
+  encoder.writeVarString(roomName)
+  encoder.writeVarUint(CONTENT_STRUCTS)
+  encoder.writeVarUint(updateCounter)
+  encoder.writeVarUint(structsBinaryEncoder.length)
+  encoder.writeBinaryEncoder(structsBinaryEncoder)
+}
+
+const CONTENT_CHECK_COUNTER = 6
+export function messageCheckUpdateCounter (roomName, encoder, updateCounter = 0) {
+  encoder.writeVarString(roomName)
+  encoder.writeVarUint(CONTENT_CHECK_COUNTER)
+  encoder.writeVarUint(updateCounter)
+}
+
+/**
+ * Decodes a client-message.
+ *
+ * A client-message consists of multiple message-elements that are concatenated without delimiter.
+ * Each has the following structure:
+ * - roomName
+ * - content_type
+ * - content (additional info that is encoded based on the value of content_type)
+ *
+ * The message is encoded until no more message-elements are available.
+ *
+ * @param {*} connector The connector that handles the connections
+ * @param {*} message The binary encoded message
+ * @param {*} ws The connection object
+ */
+export default function decodeMessage (connector, message, ws, isServer = false, persistence) {
+  const decoder = new BinaryDecoder(message)
+  const encoder = new BinaryEncoder()
+  while (decoder.hasContent()) {
+    const roomName = decoder.readVarString()
+    const contentType = decoder.readVarUint()
+    const room = connector.getRoom(roomName)
+    const y = room.y
+    switch (contentType) {
+      case CONTENT_CHECK_COUNTER:
+        const updateCounter = decoder.readVarUint()
+        if (room.localUpdateCounter !== updateCounter) {
+          messageGetSS(roomName, y, encoder)
+        }
+        connector.subscribe(roomName, ws)
+        break
+      case CONTENT_STRUCTS:
+        console.log(`${roomName}: received update`)
+        connector._mutualExclude(() => {
+          const remoteUpdateCounter = decoder.readVarUint()
+          persistence.setRemoteUpdateCounter(roomName, remoteUpdateCounter)
+          const messageLen = decoder.readVarUint()
+          if (y === null) {
+            persistence._persistStructs(roomName, decoder.readArrayBuffer(messageLen))
+          } else {
+            y.transact(() => {
+              integrateRemoteStructs(y, decoder)
+            }, true)
+          }
+        })
+        break
+      case CONTENT_GET_SS:
+        if (y !== null) {
+          messageSS(roomName, y, encoder)
+        } else {
+          persistence._createYInstance(roomName).then(y => {
+            const encoder = new BinaryEncoder()
+            messageSS(roomName, y, encoder)
+            connector.send(encoder, ws)
+          })
+        }
+        break
+      case CONTENT_SUBSCRIBE:
+        connector.subscribe(roomName, ws)
+        break
+      case CONTENT_SS:
+        // received state set
+        // reply with missing content
+        const ss = readStateSet(decoder)
+        const sendStructsDSS = () => {
+          if (y !== null) { // TODO: how to sync local content?
+            const encoder = new BinaryEncoder()
+            messageStructsDSS(roomName, y, encoder, ss, room.localUpdateCounter) // room.localUpdateHandler in case it changes
+            if (isServer) {
+              messageSS(roomName, y, encoder)
+            }
+            connector.send(encoder, ws)
+          }
+        }
+        if (room.persistenceLoaded !== undefined) {
+          room.persistenceLoaded.then(sendStructsDSS)
+        } else {
+          sendStructsDSS()
+        }
+        break
+      case CONTENT_STRUCTS_DSS:
+        console.log(`${roomName}: synced`)
+        connector._mutualExclude(() => {
+          const remoteUpdateCounter = decoder.readVarUint()
+          persistence.setRemoteUpdateCounter(roomName, remoteUpdateCounter)
+          const messageLen = decoder.readVarUint()
+          if (y === null) {
+            persistence._persistStructsDS(roomName, decoder.readArrayBuffer(messageLen))
+          } else {
+            y.transact(() => {
+              integrateRemoteStructs(y, decoder)
+              readDeleteSet(y, decoder)
+            }, true)
+          }
+        })
+        break
+      default:
+        console.error('Unexpected content type!')
+        if (ws !== null) {
+          ws.close() // TODO: specify reason
+        }
+    }
+  }
+  return encoder
+}

src/Connectors/WebsocketsConnector/server.mjs

@@ -0,0 +1,124 @@
+import Y from '../../Y.mjs'
+import uws from 'uws'
+import BinaryEncoder from '../../Util/Binary/Encoder.mjs'
+import decodeMessage, { messageStructs } from './decodeMessage.mjs'
+import FilePersistence from '../../Persistences/FilePersistence.mjs'
+
+const WebsocketsServer = uws.Server
+const persistence = new FilePersistence('.yjsPersisted')
+/**
+  * Maps from room-name to ..
+  * {
+  *   connections, // Set of ws-clients that listen to the room
+  *   y            // Yjs instance that handles the room
+  * }
+  */
+const rooms = new Map()
+/**
+ * Maps from ws-connection to Set<roomName> - the set of connected roomNames
+ */
+const connections = new Map()
+const port = process.env.PORT || 1234
+const wss = new WebsocketsServer({
+  port,
+  perMessageDeflate: {}
+})
+
+/**
+ * Set of room names that are scheduled to be sweeped (destroyed because they don't have a connection anymore)
+ */
+const scheduledSweeps = new Set()
+/* TODO: enable sweeping
+setInterval(function sweepRoomes () {
+  scheduledSweeps.forEach(roomName => {
+    const room = rooms.get(roomName)
+    if (room !== undefined) {
+      if (room.connections.size === 0) {
+        persistence.saveState(roomName, room.y).then(() => {
+          if (room.connections.size === 0) {
+            room.y.destroy()
+            rooms.delete(roomName)
+          }
+        })
+      }
+    }
+  })
+  scheduledSweeps.clear()
+}, 5000) */ 
+
+const wsConnector = {
+  send: (encoder, ws) => {
+    const message = encoder.createBuffer()
+    ws.send(message, null, null, true)
+  },
+  _mutualExclude: f => { f() },
+  subscribe: function subscribe (roomName, ws) {
+    let roomNames = connections.get(ws)
+    if (roomNames === undefined) {
+      roomNames = new Set()
+      connections.set(ws, roomNames)
+    }
+    roomNames.add(roomName)
+    const room = this.getRoom(roomName)
+    room.connections.add(ws)
+  },
+  getRoom: function getRoom (roomName) {
+    let room = rooms.get(roomName)
+    if (room === undefined) {
+      const y = new Y(roomName, null, null, { gc: true })
+      const persistenceLoaded = persistence.readState(roomName, y)
+      room = {
+        name: roomName,
+        connections: new Set(),
+        y,
+        persistenceLoaded,
+        localUpdateCounter: 1
+      }
+      y.on('afterTransaction', (y, transaction) => {
+        if (transaction.encodedStructsLen > 0) {
+          // save to persistence
+          persistence.saveUpdate(roomName, y, transaction.encodedStructs)
+          // forward update to clients
+          persistence._mutex(() => { // do not broadcast if persistence.readState is called
+            const encoder = new BinaryEncoder()
+            messageStructs(roomName, y, encoder, transaction.encodedStructs, ++room.localUpdateCounter)
+            const message = encoder.createBuffer()
+            // when changed, broakcast update to all connections
+            room.connections.forEach(conn => {
+              conn.send(message, null, null, true)
+            })
+          })
+        }
+      })
+      rooms.set(roomName, room)
+    }
+    return room
+  }
+}
+
+wss.on('connection', (ws) => {
+  ws.on('message', function onWSMessage (message) {
+    if (message.byteLength > 0) {
+      const reply = decodeMessage(wsConnector, message, ws, true, persistence)
+      if (reply.length > 0) {
+        ws.send(reply.createBuffer(), null, null, true)
+      }
+    }
+  })
+  ws.on('close', function onWSClose () {
+    const roomNames = connections.get(ws)
+    if (roomNames !== undefined) {
+      roomNames.forEach(roomName => {
+        const room = rooms.get(roomName)
+        if (room !== undefined) {
+          const connections = room.connections
+          connections.delete(ws)
+          if (connections.size === 0) {
+            scheduledSweeps.add(roomName)
+          }
+        }
+      })
+      connections.delete(ws)
+    }
+  })
+})

src/MessageHandler/binaryEncode.mjs

@@ -0,0 +1,32 @@
+
+import { writeStructs } from './syncStep1.mjs'
+import { integrateRemoteStructs } from './integrateRemoteStructs.mjs'
+import { readDeleteSet, writeDeleteSet } from './deleteSet.mjs'
+import BinaryEncoder from '../Util/Binary/Encoder.mjs'
+
+/**
+ * Read the Decoder and fill the Yjs instance with data in the decoder.
+ *
+ * @param {Y} y The Yjs instance
+ * @param {BinaryDecoder} decoder The BinaryDecoder to read from.
+ */
+export function fromBinary (y, decoder) {
+  y.transact(function () {
+    integrateRemoteStructs(y, decoder)
+    readDeleteSet(y, decoder)
+  })
+}
+
+/**
+ * Encode the Yjs model to binary format.
+ *
+ * @param {Y} y The Yjs instance
+ * @return {BinaryEncoder} The encoder instance that can be transformed
+ *                         to ArrayBuffer or Buffer.
+ */
+export function toBinary (y) {
+  let encoder = new BinaryEncoder()
+  writeStructs(y, encoder, new Map())
+  writeDeleteSet(y, encoder)
+  return encoder
+}

src/MessageHandler/deleteSet.mjs

@@ -0,0 +1,130 @@
+import { deleteItemRange } from '../Struct/Delete.mjs'
+import ID from '../Util/ID/ID.mjs'
+
+export function stringifyDeleteSet (y, decoder, strBuilder) {
+  let dsLength = decoder.readUint32()
+  for (let i = 0; i < dsLength; i++) {
+    let user = decoder.readVarUint()
+    strBuilder.push(' -' + user + ':')
+    let dvLength = decoder.readVarUint()
+    for (let j = 0; j < dvLength; j++) {
+      let from = decoder.readVarUint()
+      let len = decoder.readVarUint()
+      let gc = decoder.readUint8() === 1
+      strBuilder.push(`clock: ${from}, length: ${len}, gc: ${gc}`)
+    }
+  }
+  return strBuilder
+}
+
+export function writeDeleteSet (y, encoder) {
+  let currentUser = null
+  let currentLength
+  let lastLenPos
+
+  let numberOfUsers = 0
+  let laterDSLenPus = encoder.pos
+  encoder.writeUint32(0)
+
+  y.ds.iterate(null, null, function (n) {
+    var user = n._id.user
+    var clock = n._id.clock
+    var len = n.len
+    var gc = n.gc
+    if (currentUser !== user) {
+      numberOfUsers++
+      // a new user was found
+      if (currentUser !== null) { // happens on first iteration
+        encoder.setUint32(lastLenPos, currentLength)
+      }
+      currentUser = user
+      encoder.writeVarUint(user)
+      // pseudo-fill pos
+      lastLenPos = encoder.pos
+      encoder.writeUint32(0)
+      currentLength = 0
+    }
+    encoder.writeVarUint(clock)
+    encoder.writeVarUint(len)
+    encoder.writeUint8(gc ? 1 : 0)
+    currentLength++
+  })
+  if (currentUser !== null) { // happens on first iteration
+    encoder.setUint32(lastLenPos, currentLength)
+  }
+  encoder.setUint32(laterDSLenPus, numberOfUsers)
+}
+
+export function readDeleteSet (y, decoder) {
+  let dsLength = decoder.readUint32()
+  for (let i = 0; i < dsLength; i++) {
+    let user = decoder.readVarUint()
+    let dv = []
+    let dvLength = decoder.readUint32()
+    for (let j = 0; j < dvLength; j++) {
+      let from = decoder.readVarUint()
+      let len = decoder.readVarUint()
+      let gc = decoder.readUint8() === 1
+      dv.push([from, len, gc])
+    }
+    if (dvLength > 0) {
+      let pos = 0
+      let d = dv[pos]
+      let deletions = []
+      y.ds.iterate(new ID(user, 0), new ID(user, Number.MAX_VALUE), function (n) {
+        // cases:
+        // 1. d deletes something to the right of n
+        //  => go to next n (break)
+        // 2. d deletes something to the left of n
+        //  => create deletions
+        //  => reset d accordingly
+        //  *)=> if d doesn't delete anything anymore, go to next d (continue)
+        // 3. not 2) and d deletes something that also n deletes
+        //  => reset d so that it doesn't contain n's deletion
+        //  *)=> if d does not delete anything anymore, go to next d (continue)
+        while (d != null) {
+          var diff = 0 // describe the diff of length in 1) and 2)
+          if (n._id.clock + n.len <= d[0]) {
+            // 1)
+            break
+          } else if (d[0] < n._id.clock) {
+            // 2)
+            // delete maximum the len of d
+            // else delete as much as possible
+            diff = Math.min(n._id.clock - d[0], d[1])
+            // deleteItemRange(y, user, d[0], diff, true)
+            deletions.push([user, d[0], diff])
+          } else {
+            // 3)
+            diff = n._id.clock + n.len - d[0] // never null (see 1)
+            if (d[2] && !n.gc) {
+              // d marks as gc'd but n does not
+              // then delete either way
+              // deleteItemRange(y, user, d[0], Math.min(diff, d[1]), true)
+              deletions.push([user, d[0], Math.min(diff, d[1])])
+            }
+          }
+          if (d[1] <= diff) {
+            // d doesn't delete anything anymore
+            d = dv[++pos]
+          } else {
+            d[0] = d[0] + diff // reset pos
+            d[1] = d[1] - diff // reset length
+          }
+        }
+      })
+      // TODO: It would be more performant to apply the deletes in the above loop
+      // Adapt the Tree implementation to support delete while iterating
+      for (let i = deletions.length - 1; i >= 0; i--) {
+        const del = deletions[i]
+        deleteItemRange(y, del[0], del[1], del[2], true)
+      }
+      // for the rest.. just apply it
+      for (; pos < dv.length; pos++) {
+        d = dv[pos]
+        deleteItemRange(y, user, d[0], d[1], true)
+        // deletions.push([user, d[0], d[1], d[2]])
+      }
+    }
+  }
+}

src/MessageHandler/integrateRemoteStructs.mjs

@@ -0,0 +1,109 @@
+import { getStruct } from '../Util/structReferences.mjs'
+import BinaryDecoder from '../Util/Binary/Decoder.mjs'
+import { logID } from './messageToString.mjs'
+import GC from '../Struct/GC.mjs'
+
+class MissingEntry {
+  constructor (decoder, missing, struct) {
+    this.decoder = decoder
+    this.missing = missing.length
+    this.struct = struct
+  }
+}
+
+/**
+ * @private
+ * Integrate remote struct
+ * When a remote struct is integrated, other structs might be ready to ready to
+ * integrate.
+ */
+function _integrateRemoteStructHelper (y, struct) {
+  const id = struct._id
+  if (id === undefined) {
+    struct._integrate(y)
+  } else {
+    if (y.ss.getState(id.user) > id.clock) {
+      return
+    }
+    if (!y.gcEnabled || struct.constructor === GC || (struct._parent.constructor !== GC && struct._parent._deleted === false)) {
+      // Is either a GC or Item with an undeleted parent
+      // save to integrate
+      struct._integrate(y)
+    } else {
+      // Is an Item. parent was deleted.
+      struct._gc(y)
+    }
+    let msu = y._missingStructs.get(id.user)
+    if (msu != null) {
+      let clock = id.clock
+      const finalClock = clock + struct._length
+      for (;clock < finalClock; clock++) {
+        const missingStructs = msu.get(clock)
+        if (missingStructs !== undefined) {
+          missingStructs.forEach(missingDef => {
+            missingDef.missing--
+            if (missingDef.missing === 0) {
+              const decoder = missingDef.decoder
+              let oldPos = decoder.pos
+              let missing = missingDef.struct._fromBinary(y, decoder)
+              decoder.pos = oldPos
+              if (missing.length === 0) {
+                y._readyToIntegrate.push(missingDef.struct)
+              }
+            }
+          })
+          msu.delete(clock)
+        }
+      }
+    }
+  }
+}
+
+export function stringifyStructs (y, decoder, strBuilder) {
+  const len = decoder.readUint32()
+  for (let i = 0; i < len; i++) {
+    let reference = decoder.readVarUint()
+    let Constr = getStruct(reference)
+    let struct = new Constr()
+    let missing = struct._fromBinary(y, decoder)
+    let logMessage = '  ' + struct._logString()
+    if (missing.length > 0) {
+      logMessage += ' .. missing: ' + missing.map(logID).join(', ')
+    }
+    strBuilder.push(logMessage)
+  }
+}
+
+export function integrateRemoteStructs (y, decoder) {
+  const len = decoder.readUint32()
+  for (let i = 0; i < len; i++) {
+    let reference = decoder.readVarUint()
+    let Constr = getStruct(reference)
+    let struct = new Constr()
+    let decoderPos = decoder.pos
+    let missing = struct._fromBinary(y, decoder)
+    if (missing.length === 0) {
+      while (struct != null) {
+        _integrateRemoteStructHelper(y, struct)
+        struct = y._readyToIntegrate.shift()
+      }
+    } else {
+      let _decoder = new BinaryDecoder(decoder.uint8arr)
+      _decoder.pos = decoderPos
+      let missingEntry = new MissingEntry(_decoder, missing, struct)
+      let missingStructs = y._missingStructs
+      for (let i = missing.length - 1; i >= 0; i--) {
+        let m = missing[i]
+        if (!missingStructs.has(m.user)) {
+          missingStructs.set(m.user, new Map())
+        }
+        let msu = missingStructs.get(m.user)
+        if (!msu.has(m.clock)) {
+          msu.set(m.clock, [])
+        }
+        let mArray = msu = msu.get(m.clock)
+        mArray.push(missingEntry)
+      }
+    }
+  }
+}

src/MessageHandler/messageToString.mjs

@@ -0,0 +1,65 @@
+import BinaryDecoder from '../Util/Binary/Decoder.mjs'
+import { stringifyStructs } from './integrateRemoteStructs.mjs'
+import { stringifySyncStep1 } from './syncStep1.mjs'
+import { stringifySyncStep2 } from './syncStep2.mjs'
+import ID from '../Util/ID/ID.mjs'
+import RootID from '../Util/ID/RootID.mjs'
+import Y from '../Y.mjs'
+
+export function messageToString ([y, buffer]) {
+  let decoder = new BinaryDecoder(buffer)
+  decoder.readVarString() // read roomname
+  let type = decoder.readVarString()
+  let strBuilder = []
+  strBuilder.push('\n === ' + type + ' ===')
+  if (type === 'update') {
+    stringifyStructs(y, decoder, strBuilder)
+  } else if (type === 'sync step 1') {
+    stringifySyncStep1(y, decoder, strBuilder)
+  } else if (type === 'sync step 2') {
+    stringifySyncStep2(y, decoder, strBuilder)
+  } else {
+    strBuilder.push('-- Unknown message type - probably an encoding issue!!!')
+  }
+  return strBuilder.join('\n')
+}
+
+export function messageToRoomname (buffer) {
+  let decoder = new BinaryDecoder(buffer)
+  decoder.readVarString() // roomname
+  return decoder.readVarString() // messageType
+}
+
+export function logID (id) {
+  if (id !== null && id._id != null) {
+    id = id._id
+  }
+  if (id === null) {
+    return '()'
+  } else if (id instanceof ID) {
+    return `(${id.user},${id.clock})`
+  } else if (id instanceof RootID) {
+    return `(${id.name},${id.type})`
+  } else if (id.constructor === Y) {
+    return `y`
+  } else {
+    throw new Error('This is not a valid ID!')
+  }
+}
+
+/**
+ * Helper utility to convert an item to a readable format.
+ *
+ * @param {String} name The name of the item class (YText, ItemString, ..).
+ * @param {Item} item The item instance.
+ * @param {String} [append] Additional information to append to the returned
+ *                          string.
+ * @return {String} A readable string that represents the item object.
+ *
+ * @private
+ */
+export function logItemHelper (name, item, append) {
+  const left = item._left !== null ? item._left._lastId : null
+  const origin = item._origin !== null ? item._origin._lastId : null
+  return `${name}(id:${logID(item._id)},left:${logID(left)},origin:${logID(origin)},right:${logID(item._right)},parent:${logID(item._parent)},parentSub:${item._parentSub}${append !== undefined ? ' - ' + append : ''})`
+}

src/MessageHandler/stateSet.mjs

@@ -0,0 +1,23 @@
+
+export function readStateSet (decoder) {
+  let ss = new Map()
+  let ssLength = decoder.readUint32()
+  for (let i = 0; i < ssLength; i++) {
+    let user = decoder.readVarUint()
+    let clock = decoder.readVarUint()
+    ss.set(user, clock)
+  }
+  return ss
+}
+
+export function writeStateSet (y, encoder) {
+  let lenPosition = encoder.pos
+  let len = 0
+  encoder.writeUint32(0)
+  for (let [user, clock] of y.ss.state) {
+    encoder.writeVarUint(user)
+    encoder.writeVarUint(clock)
+    len++
+  }
+  encoder.setUint32(lenPosition, len)
+}

src/MessageHandler/syncStep1.mjs

@@ -0,0 +1,83 @@
+import BinaryEncoder from '../Util/Binary/Encoder.mjs'
+import { readStateSet, writeStateSet } from './stateSet.mjs'
+import { writeDeleteSet } from './deleteSet.mjs'
+import ID from '../Util/ID/ID.mjs'
+import { RootFakeUserID } from '../Util/ID/RootID.mjs'
+
+export function stringifySyncStep1 (y, decoder, strBuilder) {
+  let auth = decoder.readVarString()
+  let protocolVersion = decoder.readVarUint()
+  strBuilder.push(`  - auth: "${auth}"`)
+  strBuilder.push(`  - protocolVersion: ${protocolVersion}`)
+  // write SS
+  let ssBuilder = []
+  let len = decoder.readUint32()
+  for (let i = 0; i < len; i++) {
+    let user = decoder.readVarUint()
+    let clock = decoder.readVarUint()
+    ssBuilder.push(`(${user}:${clock})`)
+  }
+  strBuilder.push('  == SS: ' + ssBuilder.join(','))
+}
+
+export function sendSyncStep1 (connector, syncUser) {
+  let encoder = new BinaryEncoder()
+  encoder.writeVarString(connector.y.room)
+  encoder.writeVarString('sync step 1')
+  encoder.writeVarString(connector.authInfo || '')
+  encoder.writeVarUint(connector.protocolVersion)
+  writeStateSet(connector.y, encoder)
+  connector.send(syncUser, encoder.createBuffer())
+}
+
+/**
+ * @private
+ * Write all Items that are not not included in ss to
+ * the encoder object.
+ */
+export function writeStructs (y, encoder, ss) {
+  const lenPos = encoder.pos
+  encoder.writeUint32(0)
+  let len = 0
+  for (let user of y.ss.state.keys()) {
+    let clock = ss.get(user) || 0
+    if (user !== RootFakeUserID) {
+      const minBound = new ID(user, clock)
+      const overlappingLeft = y.os.findPrev(minBound)
+      const rightID = overlappingLeft === null ? null : overlappingLeft._id
+      if (rightID !== null && rightID.user === user && rightID.clock + overlappingLeft._length > clock) {
+        const struct = overlappingLeft._clonePartial(clock - rightID.clock)
+        struct._toBinary(encoder)
+        len++
+      }
+      y.os.iterate(minBound, new ID(user, Number.MAX_VALUE), function (struct) {
+        struct._toBinary(encoder)
+        len++
+      })
+    }
+  }
+  encoder.setUint32(lenPos, len)
+}
+
+export function readSyncStep1 (decoder, encoder, y, senderConn, sender) {
+  let protocolVersion = decoder.readVarUint()
+  // check protocol version
+  if (protocolVersion !== y.connector.protocolVersion) {
+    console.warn(
+      `You tried to sync with a Yjs instance that has a different protocol version
+      (You: ${protocolVersion}, Client: ${protocolVersion}).
+      `)
+    y.destroy()
+  }
+  // write sync step 2
+  encoder.writeVarString('sync step 2')
+  encoder.writeVarString(y.connector.authInfo || '')
+  const ss = readStateSet(decoder)
+  writeStructs(y, encoder, ss)
+  writeDeleteSet(y, encoder)
+  y.connector.send(senderConn.uid, encoder.createBuffer())
+  senderConn.receivedSyncStep2 = true
+  if (y.connector.role === 'slave') {
+    sendSyncStep1(y.connector, sender)
+  }
+}

src/MessageHandler/syncStep2.mjs

@@ -0,0 +1,28 @@
+import { stringifyStructs, integrateRemoteStructs } from './integrateRemoteStructs.mjs'
+import { readDeleteSet } from './deleteSet.mjs'
+
+export function stringifySyncStep2 (y, decoder, strBuilder) {
+  strBuilder.push('     - auth: ' + decoder.readVarString())
+  strBuilder.push('  == OS:')
+  stringifyStructs(y, decoder, strBuilder)
+  // write DS to string
+  strBuilder.push('  == DS:')
+  let len = decoder.readUint32()
+  for (let i = 0; i < len; i++) {
+    let user = decoder.readVarUint()
+    strBuilder.push(`    User: ${user}: `)
+    let len2 = decoder.readUint32()
+    for (let j = 0; j < len2; j++) {
+      let from = decoder.readVarUint()
+      let to = decoder.readVarUint()
+      let gc = decoder.readUint8() === 1
+      strBuilder.push(`[${from}, ${to}, ${gc}]`)
+    }
+  }
+}
+
+export function readSyncStep2 (decoder, encoder, y, senderConn, sender) {
+  integrateRemoteStructs(y, decoder)
+  readDeleteSet(y, decoder)
+  y.connector._setSyncedWith(sender)
+}

src/Persistence.mjs

@@ -0,0 +1,122 @@
+import BinaryEncoder from './Util/Binary/Encoder.mjs'
+import BinaryDecoder from './Util/Binary/Decoder.mjs'
+import { toBinary, fromBinary } from './MessageHandler/binaryEncode.mjs'
+import { integrateRemoteStructs } from './MessageHandler/integrateRemoteStructs.mjs'
+import { createMutualExclude } from './Util/mutualExclude.mjs'
+
+function getFreshCnf () {
+  let buffer = new BinaryEncoder()
+  buffer.writeUint32(0)
+  return {
+    len: 0,
+    buffer
+  }
+}
+
+/**
+ * Abstract persistence class.
+ */
+export default class AbstractPersistence {
+  constructor (opts) {
+    this.opts = opts
+    this.ys = new Map()
+  }
+
+  _init (y) {
+    let cnf = this.ys.get(y)
+    if (cnf === undefined) {
+      cnf = getFreshCnf()
+      cnf.mutualExclude = createMutualExclude()
+      this.ys.set(y, cnf)
+      return this.init(y).then(() => {
+        y.on('afterTransaction', (y, transaction) => {
+          let cnf = this.ys.get(y)
+          if (cnf.len > 0) {
+            cnf.buffer.setUint32(0, cnf.len)
+            this.saveUpdate(y, cnf.buffer.createBuffer(), transaction)
+            let _cnf = getFreshCnf()
+            for (let key in _cnf) {
+              cnf[key] = _cnf[key]
+            }
+          }
+        })
+        return this.retrieve(y)
+      }).then(function () {
+        return Promise.resolve(cnf)
+      })
+    } else {
+      return Promise.resolve(cnf)
+    }
+  }
+  deinit (y) {
+    this.ys.delete(y)
+    y.persistence = null
+  }
+
+  destroy () {
+    this.ys = null
+  }
+
+  /**
+   * Remove all persisted data that belongs to a room.
+   * Automatically destroys all Yjs all Yjs instances that persist to
+   * the room. If `destroyYjsInstances = false` the persistence functionality
+   * will be removed from the Yjs instances.
+   *
+   * ** Must be overwritten! **
+   */
+  removePersistedData (room, destroyYjsInstances = true) {
+    this.ys.forEach((cnf, y) => {
+      if (y.room === room) {
+        if (destroyYjsInstances) {
+          y.destroy()
+        } else {
+          this.deinit(y)
+        }
+      }
+    })
+  }
+
+  /* overwrite */
+  saveUpdate (buffer) {
+  }
+
+  /**
+   * Save struct to update buffer.
+   * saveUpdate is called when transaction ends
+   */
+  saveStruct (y, struct) {
+    let cnf = this.ys.get(y)
+    if (cnf !== undefined) {
+      cnf.mutualExclude(function () {
+        struct._toBinary(cnf.buffer)
+        cnf.len++
+      })
+    }
+  }
+
+  /* overwrite */
+  retrieve (y, model, updates) {
+    let cnf = this.ys.get(y)
+    if (cnf !== undefined) {
+      cnf.mutualExclude(function () {
+        y.transact(function () {
+          if (model != null) {
+            fromBinary(y, new BinaryDecoder(new Uint8Array(model)))
+          }
+          if (updates != null) {
+            for (let i = 0; i < updates.length; i++) {
+              integrateRemoteStructs(y, new BinaryDecoder(new Uint8Array(updates[i])))
+            }
+          }
+        })
+        y.emit('persistenceReady')
+      })
+    }
+  }
+
+  /* overwrite */
+  persist (y) {
+    return toBinary(y).createBuffer()
+  }
+}

src/Persistences/AbstractPersistence.mjs

@@ -0,0 +1,2 @@
+
+export default class AbstractPersistence {}

src/Persistences/FilePersistence.mjs

@@ -0,0 +1,72 @@
+import fs from 'fs'
+import path from 'path'
+import BinaryDecoder from '../Util/Binary/Decoder.mjs'
+import BinaryEncoder from '../Util/Binary/Encoder.mjs'
+import { createMutualExclude } from '../Util/mutualExclude.mjs'
+import { encodeUpdate, encodeStructsDS, decodePersisted } from './decodePersisted.mjs'
+
+function createFilePath (persistence, roomName) {
+  // TODO: filename checking!
+  return path.join(persistence.dir, roomName)
+}
+
+export default class FilePersistence {
+  constructor (dir) {
+    this.dir = dir
+    this._mutex = createMutualExclude()
+  }
+  setRemoteUpdateCounter (roomName, remoteUpdateCounter) {
+    // TODO: implement
+    // nop
+  }
+  saveUpdate (room, y, encodedStructs) {
+    return new Promise((resolve, reject) => {
+      this._mutex(() => {
+        const filePath = createFilePath(this, room)
+        const updateMessage = new BinaryEncoder()
+        encodeUpdate(y, encodedStructs, updateMessage)
+        fs.appendFile(filePath, Buffer.from(updateMessage.createBuffer()), (err) => {
+          if (err !== null) {
+            reject(err)
+          } else {
+            resolve()
+          }
+        })
+      }, resolve)
+    })
+  }
+  saveState (roomName, y) {
+    return new Promise((resolve, reject) => {
+      const encoder = new BinaryEncoder()
+      encodeStructsDS(y, encoder)
+      const filePath = createFilePath(this, roomName)
+      fs.writeFile(filePath, Buffer.from(encoder.createBuffer()), (err) => {
+        if (err !== null) {
+          reject(err)
+        } else {
+          resolve()
+        }
+      })
+    })
+  }
+  readState (roomName, y) {
+    // Check if the file exists in the current directory.
+    return new Promise((resolve, reject) => {
+      const filePath = path.join(this.dir, roomName)
+      fs.readFile(filePath, (err, data) => {
+        if (err !== null) {
+          resolve()
+          // reject(err)
+        } else {
+          this._mutex(() => {
+            console.info(`unpacking data (${data.length})`)
+            console.time('unpacking')
+            decodePersisted(y, new BinaryDecoder(data))
+            console.timeEnd('unpacking')
+          })
+          resolve()
+        }
+      })
+    })
+  }
+}

src/Persistences/IndexedDBPersistence.mjs

@@ -0,0 +1,283 @@
+/* global indexedDB, location, BroadcastChannel */
+
+import Y from '../Y.mjs'
+import { createMutualExclude } from '../Util/mutualExclude.mjs'
+import { decodePersisted, encodeStructsDS, encodeUpdate } from './decodePersisted.mjs'
+import BinaryDecoder from '../Util/Binary/Decoder.mjs'
+import BinaryEncoder from '../Util/Binary/Encoder.mjs'
+import { PERSIST_STRUCTS_DS } from './decodePersisted.mjs';
+import { PERSIST_UPDATE } from './decodePersisted.mjs';
+/*
+ * Request to Promise transformer
+ */
+function rtop (request) {
+  return new Promise(function (resolve, reject) {
+    request.onerror = function (event) {
+      reject(new Error(event.target.error))
+    }
+    request.onblocked = function () {
+      location.reload()
+    }
+    request.onsuccess = function (event) {
+      resolve(event.target.result)
+    }
+  })
+}
+
+function openDB (room) {
+  return new Promise(function (resolve, reject) {
+    let request = indexedDB.open(room)
+    request.onupgradeneeded = function (event) {
+      const db = event.target.result
+      if (db.objectStoreNames.contains('updates')) {
+        db.deleteObjectStore('updates')
+      }
+      db.createObjectStore('updates', {autoIncrement: true})
+    }
+    request.onerror = function (event) {
+      reject(new Error(event.target.error))
+    }
+    request.onblocked = function () {
+      location.reload()
+    }
+    request.onsuccess = function (event) {
+      const db = event.target.result
+      db.onversionchange = function () { db.close() }
+      resolve(db)
+    }
+  })
+}
+
+function persist (room) {
+  let t = room.db.transaction(['updates'], 'readwrite')
+  let updatesStore = t.objectStore('updates')
+  return rtop(updatesStore.getAll())
+  .then(updates => {
+    // apply all previous updates before deleting them
+    room.mutex(() => {
+      updates.forEach(update => {
+        decodePersisted(y, new BinaryDecoder(update))
+      })
+    })
+    const encoder = new BinaryEncoder()
+    encodeStructsDS(y, encoder)
+    // delete all pending updates
+    rtop(updatesStore.clear()).then(() => {
+      // write current model
+      updatesStore.put(encoder.createBuffer())
+    })
+  })
+}
+
+function saveUpdate (room, updateBuffer) {
+  const db = room.db
+  if (db !== null) {
+    const t = db.transaction(['updates'], 'readwrite')
+    const updatesStore = t.objectStore('updates')
+    const updatePut = rtop(updatesStore.put(updateBuffer))
+    rtop(updatesStore.count()).then(cnt => {
+      if (cnt >= PREFERRED_TRIM_SIZE) {
+        persist(room)
+      }
+    })
+    return updatePut
+  }
+}
+
+function registerRoomInPersistence (documentsDB, roomName) {
+  return documentsDB.then(
+    db => Promise.all([
+      db,
+      rtop(db.transaction(['documents'], 'readonly').objectStore('documents').get(roomName))
+    ])
+  ).then(
+    ([db, doc]) => {
+      if (doc === undefined) {
+        return rtop(db.transaction(['documents'], 'readwrite').objectStore('documents').add({ roomName, serverUpdateCounter: 0 }))
+      }
+    }
+  )
+}
+
+const PREFERRED_TRIM_SIZE = 400
+
+export default class IndexedDBPersistence {
+  constructor () {
+    this._rooms = new Map()
+    this._documentsDB = new Promise(function (resolve, reject) {
+      let request = indexedDB.open('_yjs_documents')
+      request.onupgradeneeded = function (event) {
+        const db = event.target.result
+        if (db.objectStoreNames.contains('documents')) {
+          db.deleteObjectStore('documents')
+        }
+        db.createObjectStore('documents', { keyPath: "roomName" })
+      }
+      request.onerror = function (event) {
+        reject(new Error(event.target.error))
+      }
+      request.onblocked = function () {
+        location.reload()
+      }
+      request.onsuccess = function (event) {
+        const db = event.target.result
+        db.onversionchange = function () { db.close() }
+        resolve(db)
+      }
+    })
+    addEventListener('unload', () => {
+      // close everything when page unloads
+      this._rooms.forEach(room => {
+        if (room.db !== null) {
+          room.db.close()
+        } else {
+          room.dbPromise.then(db => db.close())
+        }
+      })
+      this._documentsDB.then(db => db.close())
+    })
+  }
+  getAllDocuments () {
+    return this._documentsDB.then(
+      db => rtop(db.transaction(['documents'], 'readonly').objectStore('documents').getAll())
+    )
+  }
+  setRemoteUpdateCounter (roomName, remoteUpdateCounter) {
+    this._documentsDB.then(
+      db => rtop(db.transaction(['documents'], 'readwrite').objectStore('documents').put({ roomName, remoteUpdateCounter }))
+    )
+  }
+
+  _createYInstance (roomName) {
+    const room = this._rooms.get(roomName)
+    if (room !== undefined) {
+      return room.y
+    }
+    const y = new Y()
+    return openDB(roomName).then(
+      db => rtop(db.transaction(['updates'], 'readonly').objectStore('updates').getAll())
+    ).then(
+      updates =>
+        y.transact(() => {
+          updates.forEach(update => {
+            decodePersisted(y, new BinaryDecoder(update))
+          })
+        }, true)
+    ).then(() => Promise.resolve(y))
+  }
+
+  _persistStructsDS (roomName, structsDS) {
+    const encoder = new BinaryEncoder()
+    encoder.writeVarUint(PERSIST_STRUCTS_DS)
+    encoder.writeArrayBuffer(structsDS)
+    return openDB(roomName).then(db => {
+      const t = db.transaction(['updates'], 'readwrite')
+      const updatesStore = t.objectStore('updates')
+      return rtop(updatesStore.put(encoder.createBuffer()))
+    })
+  }
+
+  _persistStructs (roomName, structs) {
+    const encoder = new BinaryEncoder()
+    encoder.writeVarUint(PERSIST_UPDATE)
+    encoder.writeArrayBuffer(structs)
+    return openDB(roomName).then(db => {
+      const t = db.transaction(['updates'], 'readwrite')
+      const updatesStore = t.objectStore('updates')
+      return rtop(updatesStore.put(encoder.createBuffer()))
+    })
+  }
+
+  connectY (roomName, y) {
+    if (this._rooms.has(roomName)) {
+      throw new Error('A Y instance is already bound to this room!')
+    }
+    let room = {
+      db: null,
+      dbPromise: null,
+      channel: null,
+      mutex: createMutualExclude(),
+      y
+    }
+    if (typeof BroadcastChannel !== 'undefined') {
+      room.channel = new BroadcastChannel('__yjs__' + roomName)
+      room.channel.addEventListener('message', e => {
+        room.mutex(function () {
+          decodePersisted(y, new BinaryDecoder(e.data))
+        })
+      })
+    }
+    y.on('destroyed', () => {
+      this.disconnectY(roomName, y)
+    })
+    y.on('afterTransaction', (y, transaction) => {
+      room.mutex(() => {
+        if (transaction.encodedStructsLen > 0) {
+          const encoder = new BinaryEncoder()
+          const update = new BinaryEncoder()
+          encodeUpdate(y, transaction.encodedStructs, update)
+          const updateBuffer = update.createBuffer()
+          if (room.channel !== null) {
+            room.channel.postMessage(updateBuffer)
+          }
+          if (transaction.encodedStructsLen > 0) {
+            if (room.db !== null) {
+              saveUpdate(room, updateBuffer)
+            }
+          }
+        }
+      })
+    })
+    // register document in documentsDB
+    this._documentsDB.then(
+      db => 
+        rtop(db.transaction(['documents'], 'readonly').objectStore('documents').get(roomName))
+          .then(
+            doc => doc === undefined && rtop(db.transaction(['documents'], 'readwrite').objectStore('documents').add({ roomName, serverUpdateCounter: -1 }))
+          )
+    )
+    // open room db and read existing data
+    return room.dbPromise = openDB(roomName)
+      .then(db => {
+        room.db = db
+        const t = room.db.transaction(['updates'], 'readwrite')
+        const updatesStore = t.objectStore('updates')
+        // write current state as update
+        const encoder = new BinaryEncoder()
+        encodeStructsDS(y, encoder)
+        return rtop(updatesStore.put(encoder.createBuffer())).then(() => {
+          // read persisted state
+          return rtop(updatesStore.getAll()).then(updates => {
+            room.mutex(() => {
+              y.transact(() => {
+                updates.forEach(update => {
+                  decodePersisted(y, new BinaryDecoder(update))
+                })
+              }, true)
+            })
+          })
+        })
+      })
+  }
+  disconnectY (roomName) {
+    const {
+      db, channel
+    } = this._rooms.get(roomName)
+    db.close()
+    if (channel !== null) {
+      channel.close()
+    }
+    this._rooms.delete(roomName)
+  }
+
+  /**
+   * Remove all persisted data that belongs to a room.
+   * Automatically destroys all Yjs all Yjs instances that persist to
+   * the room. If `destroyYjsInstances = false` the persistence functionality
+   * will be removed from the Yjs instances.
+   */
+  removePersistedData (roomName, destroyYjsInstances = true) {
+    this.disconnectY(roomName)
+    return rtop(indexedDB.deleteDatabase(roomName))
+  }
+}

src/Persistences/decodePersisted.mjs

@@ -0,0 +1,51 @@
+import { integrateRemoteStructs } from '../MessageHandler/integrateRemoteStructs.mjs'
+import { writeStructs } from '../MessageHandler/syncStep1.mjs'
+import { writeDeleteSet, readDeleteSet } from '../MessageHandler/deleteSet.mjs'
+
+export const PERSIST_UPDATE = 0
+/**
+ * Write an update to an encoder.
+ *
+ * @param {Yjs} y A Yjs instance
+ * @param {BinaryEncoder} updateEncoder I.e. transaction.encodedStructs
+ */
+export function encodeUpdate (y, updateEncoder, encoder) {
+  encoder.writeVarUint(PERSIST_UPDATE)
+  encoder.writeBinaryEncoder(updateEncoder)
+}
+
+export const PERSIST_STRUCTS_DS = 1
+
+/**
+ * Write the current Yjs data model to an encoder.
+ *
+ * @param {Yjs} y A Yjs instance
+ * @param {BinaryEncoder} encoder An encoder to write to
+ */
+export function encodeStructsDS (y, encoder) {
+  encoder.writeVarUint(PERSIST_STRUCTS_DS)
+  writeStructs(y, encoder, new Map())
+  writeDeleteSet(y, encoder)
+}
+
+/**
+ * Feed the Yjs instance with the persisted state
+ * @param {Yjs} y A Yjs instance.
+ * @param {BinaryDecoder} decoder A Decoder instance that holds the file content.
+ */
+export function decodePersisted (y, decoder) {
+  y.transact(() => {
+    while (decoder.hasContent()) {
+      const contentType = decoder.readVarUint()
+      switch (contentType) {
+        case PERSIST_UPDATE:
+          integrateRemoteStructs(y, decoder)
+          break
+        case PERSIST_STRUCTS_DS:
+          integrateRemoteStructs(y, decoder)
+          readDeleteSet(y, decoder)
+          break
+      }
+    }
+  }, true)
+}

src/Store/DeleteStore.mjs

@@ -0,0 +1,90 @@
+
+import Tree from '../Util/Tree.mjs'
+import ID from '../Util/ID/ID.mjs'
+
+class DSNode {
+  constructor (id, len, gc) {
+    this._id = id
+    this.len = len
+    this.gc = gc
+  }
+  clone () {
+    return new DSNode(this._id, this.len, this.gc)
+  }
+}
+
+export default class DeleteStore extends Tree {
+  logTable () {
+    const deletes = []
+    this.iterate(null, null, function (n) {
+      deletes.push({
+        user: n._id.user,
+        clock: n._id.clock,
+        len: n.len,
+        gc: n.gc
+      })
+    })
+    console.table(deletes)
+  }
+  isDeleted (id) {
+    var n = this.findWithUpperBound(id)
+    return n !== null && n._id.user === id.user && id.clock < n._id.clock + n.len
+  }
+  mark (id, length, gc) {
+    if (length === 0) return
+    // Step 1. Unmark range
+    const leftD = this.findWithUpperBound(new ID(id.user, id.clock - 1))
+    // Resize left DSNode if necessary
+    if (leftD !== null && leftD._id.user === id.user) {
+      if (leftD._id.clock < id.clock && id.clock < leftD._id.clock + leftD.len) {
+        // node is overlapping. need to resize
+        if (id.clock + length < leftD._id.clock + leftD.len) {
+          // overlaps new mark range and some more
+          // create another DSNode to the right of new mark
+          this.put(new DSNode(new ID(id.user, id.clock + length), leftD._id.clock + leftD.len - id.clock - length, leftD.gc))
+        }
+        // resize left DSNode
+        leftD.len = id.clock - leftD._id.clock
+      } // Otherwise there is no overlapping
+    }
+    // Resize right DSNode if necessary
+    const upper = new ID(id.user, id.clock + length - 1)
+    const rightD = this.findWithUpperBound(upper)
+    if (rightD !== null && rightD._id.user === id.user) {
+      if (rightD._id.clock < id.clock + length && id.clock <= rightD._id.clock && id.clock + length < rightD._id.clock + rightD.len) { // we only consider the case where we resize the node
+        const d = id.clock + length - rightD._id.clock
+        rightD._id = new ID(rightD._id.user, rightD._id.clock + d)
+        rightD.len -= d
+      }
+    }
+    // Now we only have to delete all inner marks
+    const deleteNodeIds = []
+    this.iterate(id, upper, m => {
+      deleteNodeIds.push(m._id)
+    })
+    for (let i = deleteNodeIds.length - 1; i >= 0; i--) {
+      this.delete(deleteNodeIds[i])
+    }
+    let newMark = new DSNode(id, length, gc)
+    // Step 2. Check if we can extend left or right
+    if (leftD !== null && leftD._id.user === id.user && leftD._id.clock + leftD.len === id.clock && leftD.gc === gc) {
+      // We can extend left
+      leftD.len += length
+      newMark = leftD
+    }
+    const rightNext = this.find(new ID(id.user, id.clock + length))
+    if (rightNext !== null && rightNext._id.user === id.user && id.clock + length === rightNext._id.clock && gc === rightNext.gc) {
+      // We can merge newMark and rightNext
+      newMark.len += rightNext.len
+      this.delete(rightNext._id)
+    }
+    if (leftD !== newMark) {
+      // only put if we didn't extend left
+      this.put(newMark)
+    }
+  }
+  // TODO: exchange markDeleted for mark()
+  markDeleted (id, length) {
+    this.mark(id, length, false)
+  }
+}

src/Store/OperationStore.mjs

@@ -0,0 +1,94 @@
+import Tree from '../Util/Tree.mjs'
+import RootID from '../Util/ID/RootID.mjs'
+import { getStruct } from '../Util/structReferences.mjs'
+import { logID } from '../MessageHandler/messageToString.mjs'
+import GC from '../Struct/GC.mjs'
+
+export default class OperationStore extends Tree {
+  constructor (y) {
+    super()
+    this.y = y
+  }
+  logTable () {
+    const items = []
+    this.iterate(null, null, function (item) {
+      if (item.constructor === GC) {
+        items.push({
+          id: logID(item),
+          content: item._length,
+          deleted: 'GC'
+        })
+      } else {
+        items.push({
+          id: logID(item),
+          origin: logID(item._origin === null ? null : item._origin._lastId),
+          left: logID(item._left === null ? null : item._left._lastId),
+          right: logID(item._right),
+          right_origin: logID(item._right_origin),
+          parent: logID(item._parent),
+          parentSub: item._parentSub,
+          deleted: item._deleted,
+          content: JSON.stringify(item._content)
+        })
+      }
+    })
+    console.table(items)
+  }
+  get (id) {
+    let struct = this.find(id)
+    if (struct === null && id instanceof RootID) {
+      const Constr = getStruct(id.type)
+      const y = this.y
+      struct = new Constr()
+      struct._id = id
+      struct._parent = y
+      y.transact(() => {
+        struct._integrate(y)
+      })
+      this.put(struct)
+    }
+    return struct
+  }
+  // Use getItem for structs with _length > 1
+  getItem (id) {
+    var item = this.findWithUpperBound(id)
+    if (item === null) {
+      return null
+    }
+    const itemID = item._id
+    if (id.user === itemID.user && id.clock < itemID.clock + item._length) {
+      return item
+    } else {
+      return null
+    }
+  }
+  // Return an insertion such that id is the first element of content
+  // This function manipulates an item, if necessary
+  getItemCleanStart (id) {
+    var ins = this.getItem(id)
+    if (ins === null || ins._length === 1) {
+      return ins
+    }
+    const insID = ins._id
+    if (insID.clock === id.clock) {
+      return ins
+    } else {
+      return ins._splitAt(this.y, id.clock - insID.clock)
+    }
+  }
+  // Return an insertion such that id is the last element of content
+  // This function manipulates an operation, if necessary
+  getItemCleanEnd (id) {
+    var ins = this.getItem(id)
+    if (ins === null || ins._length === 1) {
+      return ins
+    }
+    const insID = ins._id
+    if (insID.clock + ins._length - 1 === id.clock) {
+      return ins
+    } else {
+      ins._splitAt(this.y, id.clock - insID.clock + 1)
+      return ins
+    }
+  }
+}

src/Store/StateStore.mjs

@@ -0,0 +1,47 @@
+import ID from '../Util/ID/ID.mjs'
+
+export default class StateStore {
+  constructor (y) {
+    this.y = y
+    this.state = new Map()
+  }
+  logTable () {
+    const entries = []
+    for (let [user, state] of this.state) {
+      entries.push({
+        user, state
+      })
+    }
+    console.table(entries)
+  }
+  getNextID (len) {
+    const user = this.y.userID
+    const state = this.getState(user)
+    this.setState(user, state + len)
+    return new ID(user, state)
+  }
+  updateRemoteState (struct) {
+    let user = struct._id.user
+    let userState = this.state.get(user)
+    while (struct !== null && struct._id.clock === userState) {
+      userState += struct._length
+      struct = this.y.os.get(new ID(user, userState))
+    }
+    this.state.set(user, userState)
+  }
+  getState (user) {
+    let state = this.state.get(user)
+    if (state == null) {
+      return 0
+    }
+    return state
+  }
+  setState (user, state) {
+    // TODO: modify missingi structs here
+    const beforeState = this.y._transaction.beforeState
+    if (!beforeState.has(user)) {
+      beforeState.set(user, this.getState(user))
+    }
+    this.state.set(user, state)
+  }
+}

src/Struct/Delete.mjs

@@ -0,0 +1,124 @@
+import { getStructReference } from '../Util/structReferences.mjs'
+import ID from '../Util/ID/ID.mjs'
+import { logID } from '../MessageHandler/messageToString.mjs'
+import { writeStructToTransaction } from '../Transaction.mjs'
+
+/**
+ * @private
+ * Delete all items in an ID-range
+ * TODO: implement getItemCleanStartNode for better performance (only one lookup)
+ */
+export function deleteItemRange (y, user, clock, range, gcChildren) {
+  const createDelete = y.connector !== null && y.connector._forwardAppliedStructs
+  let item = y.os.getItemCleanStart(new ID(user, clock))
+  if (item !== null) {
+    if (!item._deleted) {
+      item._splitAt(y, range)
+      item._delete(y, createDelete, true)
+    }
+    let itemLen = item._length
+    range -= itemLen
+    clock += itemLen
+    if (range > 0) {
+      let node = y.os.findNode(new ID(user, clock))
+      while (node !== null && node.val !== null && range > 0 && node.val._id.equals(new ID(user, clock))) {
+        const nodeVal = node.val
+        if (!nodeVal._deleted) {
+          nodeVal._splitAt(y, range)
+          nodeVal._delete(y, createDelete, gcChildren)
+        }
+        const nodeLen = nodeVal._length
+        range -= nodeLen
+        clock += nodeLen
+        node = node.next()
+      }
+    }
+  }
+}
+
+/**
+ * @private
+ * A Delete change is not a real Item, but it provides the same interface as an
+ * Item. The only difference is that it will not be saved in the ItemStore
+ * (OperationStore), but instead it is safed in the DeleteStore.
+ */
+export default class Delete {
+  constructor () {
+    this._target = null
+    this._length = null
+  }
+
+  /**
+   * @private
+   * Read the next Item in a Decoder and fill this Item with the read data.
+   *
+   * This is called when data is received from a remote peer.
+   *
+   * @param {Y} y The Yjs instance that this Item belongs to.
+   * @param {BinaryDecoder} decoder The decoder object to read data from.
+   */
+  _fromBinary (y, decoder) {
+    // TODO: set target, and add it to missing if not found
+    // There is an edge case in p2p networks!
+    const targetID = decoder.readID()
+    this._targetID = targetID
+    this._length = decoder.readVarUint()
+    if (y.os.getItem(targetID) === null) {
+      return [targetID]
+    } else {
+      return []
+    }
+  }
+
+  /**
+   * @private
+   * 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.
+   *
+   * @param {BinaryEncoder} encoder The encoder to write data to.
+   */
+  _toBinary (encoder) {
+    encoder.writeUint8(getStructReference(this.constructor))
+    encoder.writeID(this._targetID)
+    encoder.writeVarUint(this._length)
+  }
+
+  /**
+   * @private
+   * Integrates this Item into the shared structure.
+   *
+   * This method actually applies the change to the Yjs instance. In the case of
+   * Delete it marks the delete target as deleted.
+   *
+   * * If created remotely (a remote user deleted something),
+   *   this Delete is applied to all structs in id-range.
+   * * If created lokally (e.g. when y-array deletes a range of elements),
+   *   this struct is broadcasted only (it is already executed)
+   */
+  _integrate (y, locallyCreated = false) {
+    if (!locallyCreated) {
+      // from remote
+      const id = this._targetID
+      deleteItemRange(y, id.user, id.clock, this._length, false)
+    } else if (y.connector !== null) {
+      // from local
+      y.connector.broadcastStruct(this)
+    }
+    if (y.persistence !== null) {
+      y.persistence.saveStruct(y, this)
+    }
+    writeStructToTransaction(y._transaction, this)
+  }
+
+  /**
+   * Transform this YXml Type to a readable format.
+   * Useful for logging as all Items and Delete implement this method.
+   *
+   * @private
+   */
+  _logString () {
+    return `Delete - target: ${logID(this._targetID)}, len: ${this._length}`
+  }
+}

src/Struct/GC.mjs

@@ -0,0 +1,96 @@
+import { getStructReference } from '../Util/structReferences.mjs'
+import { RootFakeUserID } from '../Util/ID/RootID.mjs'
+import ID from '../Util/ID/ID.mjs'
+import { writeStructToTransaction } from '../Transaction.mjs'
+
+// TODO should have the same base class as Item
+export default class GC {
+  constructor () {
+    this._id = null
+    this._length = 0
+  }
+
+  get _deleted () {
+    return true
+  }
+
+  _integrate (y) {
+    const id = this._id
+    const userState = y.ss.getState(id.user)
+    if (id.clock === userState) {
+      y.ss.setState(id.user, id.clock + this._length)
+    }
+    y.ds.mark(this._id, this._length, true)
+    let n = y.os.put(this)
+    const prev = n.prev().val
+    if (prev !== null && prev.constructor === GC && prev._id.user === n.val._id.user && prev._id.clock + prev._length === n.val._id.clock) {
+      // TODO: do merging for all items!
+      prev._length += n.val._length
+      y.os.delete(n.val._id)
+      n = prev
+    }
+    if (n.val) {
+      n = n.val
+    }
+    const next = y.os.findNext(n._id)
+    if (next !== null && next.constructor === GC && next._id.user === n._id.user && next._id.clock === n._id.clock + n._length) {
+      n._length += next._length
+      y.os.delete(next._id)
+    }
+    if (id.user !== RootFakeUserID) {
+      if (y.connector !== null && (y.connector._forwardAppliedStructs || id.user === y.userID)) {
+        y.connector.broadcastStruct(this)
+      }
+      if (y.persistence !== null) {
+        y.persistence.saveStruct(y, this)
+      }
+      writeStructToTransaction(y._transaction, 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.
+   *
+   * @param {BinaryEncoder} encoder The encoder to write data to.
+   * @private
+   */
+  _toBinary (encoder) {
+    encoder.writeUint8(getStructReference(this.constructor))
+    encoder.writeID(this._id)
+    encoder.writeVarUint(this._length)
+  }
+
+  /**
+   * Read the next Item in a Decoder and fill this Item with the read data.
+   *
+   * This is called when data is received from a remote peer.
+   *
+   * @param {Y} y The Yjs instance that this Item belongs to.
+   * @param {BinaryDecoder} decoder The decoder object to read data from.
+   * @private
+   */
+  _fromBinary (y, decoder) {
+    const id = decoder.readID()
+    this._id = id
+    this._length = decoder.readVarUint()
+    const missing = []
+    if (y.ss.getState(id.user) < id.clock) {
+      missing.push(new ID(id.user, id.clock - 1))
+    }
+    return missing
+  }
+
+  _splitAt () {
+    return this
+  }
+
+  _clonePartial (diff) {
+    const gc = new GC()
+    gc._id = new ID(this._id.user, this._id.clock + diff)
+    gc._length = this._length - diff
+    return gc
+  }
+}

src/Struct/Item.mjs

@@ -0,0 +1,528 @@
+import { getStructReference } from '../Util/structReferences.mjs'
+import ID from '../Util/ID/ID.mjs'
+import { default as RootID, RootFakeUserID } from '../Util/ID/RootID.mjs'
+import Delete from './Delete.mjs'
+import { transactionTypeChanged, writeStructToTransaction } from '../Transaction.mjs'
+import GC from './GC.mjs'
+
+/**
+ * @private
+ * Helper utility to split an Item (see {@link Item#_splitAt})
+ * - copies all properties from a to b
+ * - connects a to b
+ * - assigns the correct _id
+ * - saves b to os
+ */
+export function splitHelper (y, a, b, diff) {
+  const aID = a._id
+  b._id = new ID(aID.user, aID.clock + diff)
+  b._origin = a
+  b._left = a
+  b._right = a._right
+  if (b._right !== null) {
+    b._right._left = b
+  }
+  b._right_origin = a._right_origin
+  // do not set a._right_origin, as this will lead to problems when syncing
+  a._right = b
+  b._parent = a._parent
+  b._parentSub = a._parentSub
+  b._deleted = a._deleted
+  // now search all relevant items to the right and update origin
+  // if origin is not it foundOrigins, we don't have to search any longer
+  let foundOrigins = new Set()
+  foundOrigins.add(a)
+  let o = b._right
+  while (o !== null && foundOrigins.has(o._origin)) {
+    if (o._origin === a) {
+      o._origin = b
+    }
+    foundOrigins.add(o)
+    o = o._right
+  }
+  y.os.put(b)
+  if (y._transaction.newTypes.has(a)) {
+    y._transaction.newTypes.add(b)
+  } else if (y._transaction.deletedStructs.has(a)) {
+    y._transaction.deletedStructs.add(b)
+  }
+}
+
+/**
+ * Abstract class that represents any content.
+ */
+export default class Item {
+  constructor () {
+    /**
+     * The uniqe identifier of this type.
+     * @type {ID}
+     */
+    this._id = null
+    /**
+     * The item that was originally to the left of this item.
+     * @type {Item}
+     */
+    this._origin = null
+    /**
+     * The item that is currently to the left of this item.
+     * @type {Item}
+     */
+    this._left = null
+    /**
+     * The item that is currently to the right of this item.
+     * @type {Item}
+     */
+    this._right = null
+    /**
+     * The item that was originally to the right of this item.
+     * @type {Item}
+     */
+    this._right_origin = null
+    /**
+     * The parent type.
+     * @type {Y|YType}
+     */
+    this._parent = null
+    /**
+     * If the parent refers to this item with some kind of key (e.g. YMap, the
+     * key is specified here. The key is then used to refer to the list in which
+     * to insert this item. If `parentSub = null` type._start is the list in
+     * which to insert to. Otherwise it is `parent._start`.
+     * @type {String}
+     */
+    this._parentSub = null
+    /**
+     * Whether this item was deleted or not.
+     * @type {Boolean}
+     */
+    this._deleted = false
+    /**
+     * If this type's effect is reundone this type refers to the type that undid
+     * this operation.
+     * @type {Item}
+     */
+    this._redone = null
+  }
+
+  /**
+   * Creates an Item with the same effect as this Item (without position effect)
+   *
+   * @private
+   */
+  _copy () {
+    return new this.constructor()
+  }
+
+  /**
+   * Redoes the effect of this operation.
+   *
+   * @param {Y} y The Yjs instance.
+   *
+   * @private
+   */
+  _redo (y) {
+    if (this._redone !== null) {
+      return this._redone
+    }
+    let struct = this._copy()
+    let left = this._left
+    let right = this
+    let parent = this._parent
+    // make sure that parent is redone
+    if (parent._deleted === true && parent._redone === null) {
+      parent._redo(y)
+    }
+    if (parent._redone !== null) {
+      parent = parent._redone
+      // find next cloned 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
+      }
+    }
+    struct._origin = left
+    struct._left = left
+    struct._right = right
+    struct._right_origin = right
+    struct._parent = parent
+    struct._parentSub = this._parentSub
+    struct._integrate(y)
+    this._redone = struct
+    return struct
+  }
+
+  /**
+   * Computes the last content address of this Item.
+   *
+   * @private
+   */
+  get _lastId () {
+    return new ID(this._id.user, this._id.clock + this._length - 1)
+  }
+
+  /**
+   * Computes the length of this Item.
+   *
+   * @private
+   */
+  get _length () {
+    return 1
+  }
+
+  /**
+   * 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
+   *
+   * @private
+   */
+  get _countable () {
+    return true
+  }
+
+  /**
+   * Splits this Item so that another Items can be inserted in-between.
+   * This must be overwritten if _length > 1
+   * Returns right part after split
+   * * diff === 0 => this
+   * * diff === length => this._right
+   * * otherwise => split _content and return right part of split
+   * (see {@link ItemJSON}/{@link ItemString} for implementation)
+   *
+   * @private
+   */
+  _splitAt (y, diff) {
+    if (diff === 0) {
+      return this
+    }
+    return this._right
+  }
+
+  /**
+   * Mark this Item as deleted.
+   *
+   * @param {Y} y The Yjs instance
+   * @param {boolean} createDelete Whether to propagate a message that this
+   *                               Type was deleted.
+   *
+   * @private
+   */
+  _delete (y, createDelete = true) {
+    if (!this._deleted) {
+      this._deleted = true
+      y.ds.mark(this._id, this._length, false)
+      let del = new Delete()
+      del._targetID = this._id
+      del._length = this._length
+      if (createDelete) {
+        // broadcast and persists Delete
+        del._integrate(y, true)
+      } else if (y.persistence !== null) {
+        // only persist Delete
+        y.persistence.saveStruct(y, del)
+      }
+      transactionTypeChanged(y, this._parent, this._parentSub)
+      y._transaction.deletedStructs.add(this)
+    }
+  }
+
+  _gcChildren (y) {}
+
+  _gc (y) {
+    const gc = new GC()
+    gc._id = this._id
+    gc._length = this._length
+    y.os.delete(this._id)
+    gc._integrate(y)
+  }
+
+  /**
+   * This is called right before this Item receives any children.
+   * It can be overwritten to apply pending changes before applying remote changes
+   *
+   * @private
+   */
+  _beforeChange () {
+    // nop
+  }
+
+  /**
+   * Integrates this Item into the shared structure.
+   *
+   * This method actually applies the change to the Yjs instance. In case of
+   * Item it connects _left and _right to this Item and calls the
+   * {@link Item#beforeChange} method.
+   *
+   * * Integrate the struct so that other types/structs can see it
+   * * Add this struct to y.os
+   * * Check if this is struct deleted
+   *
+   * @private
+   */
+  _integrate (y) {
+    y._transaction.newTypes.add(this)
+    const parent = this._parent
+    const selfID = this._id
+    const user = selfID === null ? y.userID : selfID.user
+    const userState = y.ss.getState(user)
+    if (selfID === null) {
+      this._id = y.ss.getNextID(this._length)
+    } else if (selfID.user === RootFakeUserID) {
+      // nop
+    } else if (selfID.clock < userState) {
+      // already applied..
+      return []
+    } else if (selfID.clock === userState) {
+      y.ss.setState(selfID.user, userState + this._length)
+    } else {
+      // missing content from user
+      throw new Error('Can not apply yet!')
+    }
+    if (!parent._deleted && !y._transaction.changedTypes.has(parent) && !y._transaction.newTypes.has(parent)) {
+      // this is the first time parent is updated
+      // or this types is new
+      this._parent._beforeChange()
+    }
+
+    /*
+    # $this has to find a unique position between origin and the next known character
+    # case 1: $origin equals $o.origin: the $creator parameter decides if left or right
+    #         let $OL= [o1,o2,o3,o4], whereby $this is to be inserted between o1 and o4
+    #         o2,o3 and o4 origin is 1 (the position of o2)
+    #         there is the case that $this.creator < o2.creator, but o3.creator < $this.creator
+    #         then o2 knows o3. Since on another client $OL could be [o1,o3,o4] the problem is complex
+    #         therefore $this would be always to the right of o3
+    # case 2: $origin < $o.origin
+    #         if current $this insert_position > $o origin: $this ins
+    #         else $insert_position will not change
+    #         (maybe we encounter case 1 later, then this will be to the right of $o)
+    # case 3: $origin > $o.origin
+    #         $this insert_position is to the left of $o (forever!)
+    */
+    // handle conflicts
+    let o
+    // set o to the first conflicting item
+    if (this._left !== null) {
+      o = this._left._right
+    } else if (this._parentSub !== null) {
+      o = this._parent._map.get(this._parentSub) || null
+    } else {
+      o = this._parent._start
+    }
+    let conflictingItems = new Set()
+    let itemsBeforeOrigin = new Set()
+    // Let c in conflictingItems, b in itemsBeforeOrigin
+    // ***{origin}bbbb{this}{c,b}{c,b}{o}***
+    // Note that conflictingItems is a subset of itemsBeforeOrigin
+    while (o !== null && o !== this._right) {
+      itemsBeforeOrigin.add(o)
+      conflictingItems.add(o)
+      if (this._origin === o._origin) {
+        // case 1
+        if (o._id.user < this._id.user) {
+          this._left = o
+          conflictingItems.clear()
+        }
+      } else if (itemsBeforeOrigin.has(o._origin)) {
+        // case 2
+        if (!conflictingItems.has(o._origin)) {
+          this._left = o
+          conflictingItems.clear()
+        }
+      } else {
+        break
+      }
+      // TODO: try to use right_origin instead.
+      // Then you could basically omit conflictingItems!
+      // Note: you probably can't use right_origin in every case.. only when setting _left
+      o = o._right
+    }
+    // reconnect left/right + update parent map/start if necessary
+    const parentSub = this._parentSub
+    if (this._left === null) {
+      let right
+      if (parentSub !== null) {
+        const pmap = parent._map
+        right = pmap.get(parentSub) || null
+        pmap.set(parentSub, this)
+      } else {
+        right = parent._start
+        parent._start = this
+      }
+      this._right = right
+      if (right !== null) {
+        right._left = this
+      }
+    } else {
+      const left = this._left
+      const right = left._right
+      this._right = right
+      left._right = this
+      if (right !== null) {
+        right._left = this
+      }
+    }
+    if (parent._deleted) {
+      this._delete(y, false)
+    }
+    y.os.put(this)
+    transactionTypeChanged(y, parent, parentSub)
+    if (this._id.user !== RootFakeUserID) {
+      if (y.connector !== null && (y.connector._forwardAppliedStructs || this._id.user === y.userID)) {
+        y.connector.broadcastStruct(this)
+      }
+      if (y.persistence !== null) {
+        y.persistence.saveStruct(y, this)
+      }
+      writeStructToTransaction(y._transaction, 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.
+   *
+   * @param {BinaryEncoder} encoder The encoder to write data to.
+   *
+   * @private
+   */
+  _toBinary (encoder) {
+    encoder.writeUint8(getStructReference(this.constructor))
+    let info = 0
+    if (this._origin !== null) {
+      info += 0b1 // origin is defined
+    }
+    // TODO: remove
+    /* no longer send _left
+    if (this._left !== this._origin) {
+      info += 0b10 // do not copy origin to left
+    }
+    */
+    if (this._right_origin !== null) {
+      info += 0b100
+    }
+    if (this._parentSub !== null) {
+      info += 0b1000
+    }
+    encoder.writeUint8(info)
+    encoder.writeID(this._id)
+    if (info & 0b1) {
+      encoder.writeID(this._origin._lastId)
+    }
+    // TODO: remove
+    /* see above
+    if (info & 0b10) {
+      encoder.writeID(this._left._lastId)
+    }
+    */
+    if (info & 0b100) {
+      encoder.writeID(this._right_origin._id)
+    }
+    if ((info & 0b101) === 0) {
+      // neither origin nor right is defined
+      encoder.writeID(this._parent._id)
+    }
+    if (info & 0b1000) {
+      encoder.writeVarString(JSON.stringify(this._parentSub))
+    }
+  }
+
+  /**
+   * Read the next Item in a Decoder and fill this Item with the read data.
+   *
+   * This is called when data is received from a remote peer.
+   *
+   * @param {Y} y The Yjs instance that this Item belongs to.
+   * @param {BinaryDecoder} decoder The decoder object to read data from.
+   *
+   * @private
+   */
+  _fromBinary (y, decoder) {
+    let missing = []
+    const info = decoder.readUint8()
+    const id = decoder.readID()
+    this._id = id
+    // read origin
+    if (info & 0b1) {
+      // origin != null
+      const originID = decoder.readID()
+      // we have to query for left again because it might have been split/merged..
+      const origin = y.os.getItemCleanEnd(originID)
+      if (origin === null) {
+        missing.push(originID)
+      } else {
+        this._origin = origin
+        this._left = this._origin
+      }
+    }
+    // read right
+    if (info & 0b100) {
+      // right != null
+      const rightID = decoder.readID()
+      // we have to query for right again because it might have been split/merged..
+      const right = y.os.getItemCleanStart(rightID)
+      if (right === null) {
+        missing.push(rightID)
+      } else {
+        this._right = right
+        this._right_origin = right
+      }
+    }
+    // read parent
+    if ((info & 0b101) === 0) {
+      // neither origin nor right is defined
+      const parentID = decoder.readID()
+      // parent does not change, so we don't have to search for it again
+      if (this._parent === null) {
+        let parent
+        if (parentID.constructor === RootID) {
+          parent = y.os.get(parentID)
+        } else {
+          parent = y.os.getItem(parentID)
+        }
+        if (parent === null) {
+          missing.push(parentID)
+        } else {
+          this._parent = parent
+        }
+      }
+    } else if (this._parent === null) {
+      if (this._origin !== null) {
+        if (this._origin.constructor === GC) {
+          // if origin is a gc, set parent also gc'd
+          this._parent = this._origin
+        } else {
+          this._parent = this._origin._parent
+        }
+      } else if (this._right_origin !== null) {
+        // if origin is a gc, set parent also gc'd
+        if (this._right_origin.constructor === GC) {
+          this._parent = this._right_origin
+        } else {
+          this._parent = this._right_origin._parent
+        }
+      }
+    }
+    if (info & 0b1000) {
+      // TODO: maybe put this in read parent condition (you can also read parentsub from left/right)
+      this._parentSub = JSON.parse(decoder.readVarString())
+    }
+    if (y.ss.getState(id.user) < id.clock) {
+      missing.push(new ID(id.user, id.clock - 1))
+    }
+    return missing
+  }
+}

src/Struct/ItemEmbed.mjs

@@ -0,0 +1,35 @@
+import Item from './Item.mjs'
+import { logItemHelper } from '../MessageHandler/messageToString.mjs'
+
+export default class ItemEmbed extends Item {
+  constructor () {
+    super()
+    this.embed = null
+  }
+  _copy (undeleteChildren, copyPosition) {
+    let struct = super._copy(undeleteChildren, copyPosition)
+    struct.embed = this.embed
+    return struct
+  }
+  get _length () {
+    return 1
+  }
+  _fromBinary (y, decoder) {
+    const missing = super._fromBinary(y, decoder)
+    this.embed = JSON.parse(decoder.readVarString())
+    return missing
+  }
+  _toBinary (encoder) {
+    super._toBinary(encoder)
+    encoder.writeVarString(JSON.stringify(this.embed))
+  }
+  /**
+   * Transform this YXml Type to a readable format.
+   * Useful for logging as all Items and Delete implement this method.
+   *
+   * @private
+   */
+  _logString () {
+    return logItemHelper('ItemEmbed', this, `embed:${JSON.stringify(this.embed)}`)
+  }
+}

src/Struct/ItemFormat.mjs

@@ -0,0 +1,42 @@
+import Item from './Item.mjs'
+import { logItemHelper } from '../MessageHandler/messageToString.mjs'
+
+export default class ItemFormat extends Item {
+  constructor () {
+    super()
+    this.key = null
+    this.value = null
+  }
+  _copy (undeleteChildren, copyPosition) {
+    let struct = super._copy(undeleteChildren, copyPosition)
+    struct.key = this.key
+    struct.value = this.value
+    return struct
+  }
+  get _length () {
+    return 1
+  }
+  get _countable () {
+    return false
+  }
+  _fromBinary (y, decoder) {
+    const missing = super._fromBinary(y, decoder)
+    this.key = decoder.readVarString()
+    this.value = JSON.parse(decoder.readVarString())
+    return missing
+  }
+  _toBinary (encoder) {
+    super._toBinary(encoder)
+    encoder.writeVarString(this.key)
+    encoder.writeVarString(JSON.stringify(this.value))
+  }
+  /**
+   * Transform this YXml Type to a readable format.
+   * Useful for logging as all Items and Delete implement this method.
+   *
+   * @private
+   */
+  _logString () {
+    return logItemHelper('ItemFormat', this, `key:${JSON.stringify(this.key)},value:${JSON.stringify(this.value)}`)
+  }
+}

src/Struct/ItemJSON.mjs

@@ -0,0 +1,68 @@
+import Item, { splitHelper } from './Item.mjs'
+import { logItemHelper } from '../MessageHandler/messageToString.mjs'
+
+export default class ItemJSON extends Item {
+  constructor () {
+    super()
+    this._content = null
+  }
+  _copy () {
+    let struct = super._copy()
+    struct._content = this._content
+    return struct
+  }
+  get _length () {
+    return this._content.length
+  }
+  _fromBinary (y, decoder) {
+    let missing = super._fromBinary(y, decoder)
+    let len = decoder.readVarUint()
+    this._content = new Array(len)
+    for (let i = 0; i < len; i++) {
+      const ctnt = decoder.readVarString()
+      let parsed
+      if (ctnt === 'undefined') {
+        parsed = undefined
+      } else {
+        parsed = JSON.parse(ctnt)
+      }
+      this._content[i] = parsed
+    }
+    return missing
+  }
+  _toBinary (encoder) {
+    super._toBinary(encoder)
+    let len = this._content.length
+    encoder.writeVarUint(len)
+    for (let i = 0; i < len; i++) {
+      let encoded
+      let content = this._content[i]
+      if (content === undefined) {
+        encoded = 'undefined'
+      } else {
+        encoded = JSON.stringify(content)
+      }
+      encoder.writeVarString(encoded)
+    }
+  }
+  /**
+   * Transform this YXml Type to a readable format.
+   * Useful for logging as all Items and Delete implement this method.
+   *
+   * @private
+   */
+  _logString () {
+    return logItemHelper('ItemJSON', this, `content:${JSON.stringify(this._content)}`)
+  }
+  _splitAt (y, diff) {
+    if (diff === 0) {
+      return this
+    } else if (diff >= this._length) {
+      return this._right
+    }
+    let item = new ItemJSON()
+    item._content = this._content.splice(diff)
+    splitHelper(y, this, item, diff)
+    return item
+  }
+}

src/Struct/ItemString.mjs

@@ -0,0 +1,47 @@
+import Item, { splitHelper } from './Item.mjs'
+import { logItemHelper } from '../MessageHandler/messageToString.mjs'
+
+export default class ItemString extends Item {
+  constructor () {
+    super()
+    this._content = null
+  }
+  _copy () {
+    let struct = super._copy()
+    struct._content = this._content
+    return struct
+  }
+  get _length () {
+    return this._content.length
+  }
+  _fromBinary (y, decoder) {
+    let missing = super._fromBinary(y, decoder)
+    this._content = decoder.readVarString()
+    return missing
+  }
+  _toBinary (encoder) {
+    super._toBinary(encoder)
+    encoder.writeVarString(this._content)
+  }
+  /**
+   * Transform this YXml Type to a readable format.
+   * Useful for logging as all Items and Delete implement this method.
+   *
+   * @private
+   */
+  _logString () {
+    return logItemHelper('ItemString', this, `content:"${this._content}"`)
+  }
+  _splitAt (y, diff) {
+    if (diff === 0) {
+      return this
+    } else if (diff >= this._length) {
+      return this._right
+    }
+    let item = new ItemString()
+    item._content = this._content.slice(diff)
+    this._content = this._content.slice(0, diff)
+    splitHelper(y, this, item, diff)
+    return item
+  }
+}

src/Struct/Type.mjs

@@ -0,0 +1,243 @@
+import Item from './Item.mjs'
+import EventHandler from '../Util/EventHandler.mjs'
+import ID from '../Util/ID/ID.mjs'
+
+// restructure children as if they were inserted one after another
+function integrateChildren (y, start) {
+  let right
+  do {
+    right = start._right
+    start._right = null
+    start._right_origin = null
+    start._origin = start._left
+    start._integrate(y)
+    start = right
+  } while (right !== null)
+}
+
+export function getListItemIDByPosition (type, i) {
+  let pos = 0
+  let n = type._start
+  while (n !== null) {
+    if (!n._deleted) {
+      if (pos <= i && i < pos + n._length) {
+        const id = n._id
+        return new ID(id.user, id.clock + i - pos)
+      }
+      pos++
+    }
+    n = n._right
+  }
+}
+
+function gcChildren (y, item) {
+  while (item !== null) {
+    item._delete(y, false, true)
+    item._gc(y)
+    item = item._right
+  }
+}
+
+/**
+ * Abstract Yjs Type class
+ */
+export default class Type extends Item {
+  constructor () {
+    super()
+    this._map = new Map()
+    this._start = null
+    this._y = null
+    this._eventHandler = new EventHandler()
+    this._deepEventHandler = new EventHandler()
+  }
+
+  /**
+   * Compute the path from this type to the specified target.
+   *
+   * @example
+   * It should be accessible via `this.get(result[0]).get(result[1])..`
+   * const path = type.getPathTo(child)
+   * // assuming `type instanceof YArray`
+   * console.log(path) // might look like => [2, 'key1']
+   * child === type.get(path[0]).get(path[1])
+   *
+   * @param {YType} type Type target
+   * @return {Array<string>} Path to the target
+   */
+  getPathTo (type) {
+    if (type === this) {
+      return []
+    }
+    const path = []
+    const y = this._y
+    while (type !== this && type !== y) {
+      let parent = type._parent
+      if (type._parentSub !== null) {
+        path.unshift(type._parentSub)
+      } else {
+        // parent is array-ish
+        for (let [i, child] of parent) {
+          if (child === type) {
+            path.unshift(i)
+            break
+          }
+        }
+      }
+      type = parent
+    }
+    if (type !== this) {
+      throw new Error('The type is not a child of this node')
+    }
+    return path
+  }
+
+  /**
+   * @private
+   * Call event listeners with an event. This will also add an event to all
+   * parents (for `.observeDeep` handlers).
+   */
+  _callEventHandler (transaction, event) {
+    const changedParentTypes = transaction.changedParentTypes
+    this._eventHandler.callEventListeners(transaction, event)
+    let type = this
+    while (type !== this._y) {
+      let events = changedParentTypes.get(type)
+      if (events === undefined) {
+        events = []
+        changedParentTypes.set(type, events)
+      }
+      events.push(event)
+      type = type._parent
+    }
+  }
+
+  /**
+   * @private
+   * Helper method to transact if the y instance is available.
+   *
+   * TODO: Currently event handlers are not thrown when a type is not registered
+   *       with a Yjs instance.
+   */
+  _transact (f) {
+    const y = this._y
+    if (y !== null) {
+      y.transact(f)
+    } else {
+      f(y)
+    }
+  }
+
+  /**
+   * Observe all events that are created on this type.
+   *
+   * @param {Function} f Observer function
+   */
+  observe (f) {
+    this._eventHandler.addEventListener(f)
+  }
+
+  /**
+   * Observe all events that are created by this type and its children.
+   *
+   * @param {Function} f Observer function
+   */
+  observeDeep (f) {
+    this._deepEventHandler.addEventListener(f)
+  }
+
+  /**
+   * Unregister an observer function.
+   *
+   * @param {Function} f Observer function
+   */
+  unobserve (f) {
+    this._eventHandler.removeEventListener(f)
+  }
+
+  /**
+   * Unregister an observer function.
+   *
+   * @param {Function} f Observer function
+   */
+  unobserveDeep (f) {
+    this._deepEventHandler.removeEventListener(f)
+  }
+
+  /**
+   * @private
+   * 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 {Y} y The Yjs instance
+   */
+  _integrate (y) {
+    super._integrate(y)
+    this._y = y
+    // when integrating children we must make sure to
+    // integrate start
+    const start = this._start
+    if (start !== null) {
+      this._start = null
+      integrateChildren(y, start)
+    }
+    // integrate map children
+    const map = this._map
+    this._map = new Map()
+    for (let t of map.values()) {
+      // TODO make sure that right elements are deleted!
+      integrateChildren(y, t)
+    }
+  }
+
+  _gcChildren (y) {
+    gcChildren(y, this._start)
+    this._start = null
+    this._map.forEach(item => {
+      gcChildren(y, item)
+    })
+    this._map = new Map()
+  }
+
+  _gc (y) {
+    this._gcChildren(y)
+    super._gc(y)
+  }
+
+  /**
+   * @private
+   * Mark this Item as deleted.
+   *
+   * @param {Y} y The Yjs instance
+   * @param {boolean} createDelete Whether to propagate a message that this
+   *                               Type was deleted.
+   * @param {boolean} [gcChildren=y._hasUndoManager===false] Whether to garbage
+   *                                         collect the children of this type.
+   */
+  _delete (y, createDelete, gcChildren) {
+    if (gcChildren === undefined || !y.gcEnabled) {
+      gcChildren = y._hasUndoManager === false && y.gcEnabled
+    }
+    super._delete(y, createDelete, gcChildren)
+    y._transaction.changedTypes.delete(this)
+    // delete map types
+    for (let value of this._map.values()) {
+      if (value instanceof Item && !value._deleted) {
+        value._delete(y, false, gcChildren)
+      }
+    }
+    // delete array types
+    let t = this._start
+    while (t !== null) {
+      if (!t._deleted) {
+        t._delete(y, false, gcChildren)
+      }
+      t = t._right
+    }
+    if (gcChildren) {
+      this._gcChildren(y)
+    }
+  }
+}

src/Transaction.mjs

@@ -0,0 +1,91 @@
+import BinaryEncoder from './Util/Binary/Encoder.mjs'
+
+/**
+ * A transaction is created for every change on the Yjs model. It is possible
+ * to bundle changes on the Yjs model in a single transaction to
+ * minimize the number on messages sent and the number of observer calls.
+ * If possible the user of this library should bundle as many changes as
+ * possible. Here is an example to illustrate the advantages of bundling:
+ *
+ * @example
+ * const map = y.define('map', YMap)
+ * // Log content when change is triggered
+ * map.observe(function () {
+ *   console.log('change triggered')
+ * })
+ * // Each change on the map type triggers a log message:
+ * map.set('a', 0) // => "change triggered"
+ * map.set('b', 0) // => "change triggered"
+ * // When put in a transaction, it will trigger the log after the transaction:
+ * y.transact(function () {
+ *   map.set('a', 1)
+ *   map.set('b', 1)
+ * }) // => "change triggered"
+ *
+ */
+export default class Transaction {
+  constructor (y) {
+    /**
+     * @type {Y} The Yjs instance.
+     */
+    this.y = y
+    /**
+     * All new types that are added during a transaction.
+     * @type {Set<Item>}
+     */
+    this.newTypes = new Set()
+    /**
+     * All types that were directly modified (property added or child
+     * inserted/deleted). New types are not included in this Set.
+     * Maps from type to parentSubs (`item._parentSub = null` for YArray)
+     * @type {Set<YType,String>}
+     */
+    this.changedTypes = new Map()
+    // TODO: rename deletedTypes
+    /**
+     * Set of all deleted Types and Structs.
+     * @type {Set<Item>}
+     */
+    this.deletedStructs = new Set()
+    /**
+     * Saves the old state set of the Yjs instance. If a state was modified,
+     * the original value is saved here.
+     * @type {Map<Number,Number>}
+     */
+    this.beforeState = new Map()
+    /**
+     * Stores the events for the types that observe also child elements.
+     * It is mainly used by `observeDeep`.
+     * @type {Map<YType,Array<YEvent>>}
+     */
+    this.changedParentTypes = new Map()
+    this.encodedStructsLen = 0
+    this._encodedStructs = new BinaryEncoder()
+    this._encodedStructs.writeUint32(0)
+  }
+  get encodedStructs () {
+    this._encodedStructs.setUint32(0, this.encodedStructsLen)
+    return this._encodedStructs
+  }
+}
+
+export function writeStructToTransaction (transaction, struct) {
+  transaction.encodedStructsLen++
+  struct._toBinary(transaction._encodedStructs)
+}
+
+/**
+ * @private
+ */
+export function transactionTypeChanged (y, type, sub) {
+  if (type !== y && !type._deleted && !y._transaction.newTypes.has(type)) {
+    const changedTypes = y._transaction.changedTypes
+    let subs = changedTypes.get(type)
+    if (subs === undefined) {
+      // create if it doesn't exist yet
+      subs = new Set()
+      changedTypes.set(type, subs)
+    }
+    subs.add(sub)
+  }
+}

src/Types/YArray/YArray.mjs

@@ -0,0 +1,378 @@
+import Type from '../../Struct/Type.mjs'
+import ItemJSON from '../../Struct/ItemJSON.mjs'
+import ItemString from '../../Struct/ItemString.mjs'
+import { logID, logItemHelper } from '../../MessageHandler/messageToString.mjs'
+import YEvent from '../../Util/YEvent.mjs'
+
+/**
+ * Event that describes the changes on a YArray
+ *
+ * @param {YArray} yarray The changed type
+ * @param {Boolean} remote Whether the changed was caused by a remote peer
+ * @param {Transaction} transaction The transaction object
+ */
+export class YArrayEvent extends YEvent {
+  constructor (yarray, remote, transaction) {
+    super(yarray)
+    this.remote = remote
+    this._transaction = transaction
+    this._addedElements = null
+    this._removedElements = null
+  }
+
+  /**
+   * Child elements that were added in this transaction.
+   *
+   * @return {Set}
+   */
+  get addedElements () {
+    if (this._addedElements === null) {
+      const target = this.target
+      const transaction = this._transaction
+      const addedElements = new Set()
+      transaction.newTypes.forEach(function (type) {
+        if (type._parent === target && !transaction.deletedStructs.has(type)) {
+          addedElements.add(type)
+        }
+      })
+      this._addedElements = addedElements
+    }
+    return this._addedElements
+  }
+
+  /**
+   * Child elements that were removed in this transaction.
+   *
+   * @return {Set}
+   */
+  get removedElements () {
+    if (this._removedElements === null) {
+      const target = this.target
+      const transaction = this._transaction
+      const removedElements = new Set()
+      transaction.deletedStructs.forEach(function (struct) {
+        if (struct._parent === target && !transaction.newTypes.has(struct)) {
+          removedElements.add(struct)
+        }
+      })
+      this._removedElements = removedElements
+    }
+    return this._removedElements
+  }
+}
+
+/**
+ * A shared Array implementation.
+ */
+export default class YArray extends Type {
+  /**
+   * @private
+   * Creates YArray Event and calls observers.
+   */
+  _callObserver (transaction, parentSubs, remote) {
+    this._callEventHandler(transaction, new YArrayEvent(this, remote, transaction))
+  }
+
+  /**
+   * Returns the i-th element from a YArray.
+   *
+   * @param {Integer} index The index of the element to return from the YArray
+   */
+  get (index) {
+    let n = this._start
+    while (n !== null) {
+      if (!n._deleted && n._countable) {
+        if (index < n._length) {
+          if (n.constructor === ItemJSON || n.constructor === ItemString) {
+            return n._content[index]
+          } else {
+            return n
+          }
+        }
+        index -= n._length
+      }
+      n = n._right
+    }
+  }
+
+  /**
+   * Transforms this YArray to a JavaScript Array.
+   *
+   * @return {Array}
+   */
+  toArray () {
+    return this.map(c => c)
+  }
+
+  /**
+   * Transforms this Shared Type to a JSON object.
+   *
+   * @return {Array}
+   */
+  toJSON () {
+    return this.map(c => {
+      if (c instanceof Type) {
+        if (c.toJSON !== null) {
+          return c.toJSON()
+        } else {
+          return c.toString()
+        }
+      }
+      return c
+    })
+  }
+
+  /**
+   * Returns an Array with the result of calling a provided function on every
+   * element of this YArray.
+   *
+   * @param {Function} f Function that produces an element of the new Array
+   * @return {Array} A new array with each element being the result of the
+   *                 callback function
+   */
+  map (f) {
+    const res = []
+    this.forEach((c, i) => {
+      res.push(f(c, i, this))
+    })
+    return res
+  }
+
+  /**
+   * Executes a provided function on once on overy element of this YArray.
+   *
+   * @param {Function} f A function to execute on every element of this YArray.
+   */
+  forEach (f) {
+    let index = 0
+    let n = this._start
+    while (n !== null) {
+      if (!n._deleted && n._countable) {
+        if (n instanceof Type) {
+          f(n, index++, this)
+        } else {
+          const content = n._content
+          const contentLen = content.length
+          for (let i = 0; i < contentLen; i++) {
+            index++
+            f(content[i], index, this)
+          }
+        }
+      }
+      n = n._right
+    }
+  }
+
+  /**
+   * Computes the length of this YArray.
+   */
+  get length () {
+    let length = 0
+    let n = this._start
+    while (n !== null) {
+      if (!n._deleted && n._countable) {
+        length += n._length
+      }
+      n = n._right
+    }
+    return length
+  }
+
+  [Symbol.iterator] () {
+    return {
+      next: function () {
+        while (this._item !== null && (this._item._deleted || this._item._length <= this._itemElement)) {
+          // item is deleted or itemElement does not exist (is deleted)
+          this._item = this._item._right
+          this._itemElement = 0
+        }
+        if (this._item === null) {
+          return {
+            done: true
+          }
+        }
+        let content
+        if (this._item instanceof Type) {
+          content = this._item
+        } else {
+          content = this._item._content[this._itemElement++]
+        }
+        return {
+          value: content,
+          done: false
+        }
+      },
+      _item: this._start,
+      _itemElement: 0,
+      _count: 0
+    }
+  }
+
+  /**
+   * Deletes elements starting from an index.
+   *
+   * @param {Integer} index Index at which to start deleting elements
+   * @param {Integer} length The number of elements to remove. Defaults to 1.
+   */
+  delete (index, length = 1) {
+    this._y.transact(() => {
+      let item = this._start
+      let count = 0
+      while (item !== null && length > 0) {
+        if (!item._deleted && item._countable) {
+          if (count <= index && index < count + item._length) {
+            const diffDel = index - count
+            item = item._splitAt(this._y, diffDel)
+            item._splitAt(this._y, length)
+            length -= item._length
+            item._delete(this._y)
+            count += diffDel
+          } else {
+            count += item._length
+          }
+        }
+        item = item._right
+      }
+    })
+    if (length > 0) {
+      throw new Error('Delete exceeds the range of the YArray')
+    }
+  }
+
+  /**
+   * @private
+   * Inserts content after an element container.
+   *
+   * @param {Item} left The element container to use as a reference.
+   * @param {Array} content The Array of content to insert (see {@see insert})
+   */
+  insertAfter (left, content) {
+    this._transact(y => {
+      let right
+      if (left === null) {
+        right = this._start
+      } else {
+        right = left._right
+      }
+      let prevJsonIns = null
+      for (let i = 0; i < content.length; i++) {
+        let c = content[i]
+        if (typeof c === 'function') {
+          c = new c() // eslint-disable-line new-cap
+        }
+        if (c instanceof Type) {
+          if (prevJsonIns !== null) {
+            if (y !== null) {
+              prevJsonIns._integrate(y)
+            }
+            left = prevJsonIns
+            prevJsonIns = null
+          }
+          c._origin = left
+          c._left = left
+          c._right = right
+          c._right_origin = right
+          c._parent = this
+          if (y !== null) {
+            c._integrate(y)
+          } else if (left === null) {
+            this._start = c
+          } else {
+            left._right = c
+          }
+          left = c
+        } else {
+          if (prevJsonIns === null) {
+            prevJsonIns = new ItemJSON()
+            prevJsonIns._origin = left
+            prevJsonIns._left = left
+            prevJsonIns._right = right
+            prevJsonIns._right_origin = right
+            prevJsonIns._parent = this
+            prevJsonIns._content = []
+          }
+          prevJsonIns._content.push(c)
+        }
+      }
+      if (prevJsonIns !== null) {
+        if (y !== null) {
+          prevJsonIns._integrate(y)
+        } else if (prevJsonIns._left === null) {
+          this._start = prevJsonIns
+        }
+      }
+    })
+    return content
+  }
+
+  /**
+   * 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(2, [1, 2])
+   *
+   * @param {Integer} index The index to insert content at.
+   * @param {Array} content The array of content
+   */
+  insert (index, content) {
+    this._transact(() => {
+      let left = null
+      let right = this._start
+      let count = 0
+      const y = this._y
+      while (right !== null) {
+        const rightLen = right._deleted ? 0 : (right._length - 1)
+        if (count <= index && index <= count + rightLen) {
+          const splitDiff = index - count
+          right = right._splitAt(y, splitDiff)
+          left = right._left
+          count += splitDiff
+          break
+        }
+        if (!right._deleted) {
+          count += right._length
+        }
+        left = right
+        right = right._right
+      }
+      if (index > count) {
+        throw new Error('Index exceeds array range!')
+      }
+      this.insertAfter(left, content)
+    })
+  }
+
+  /**
+   * Appends content to this YArray.
+   *
+   * @param {Array} content Array of content to append.
+   */
+  push (content) {
+    let n = this._start
+    let lastUndeleted = null
+    while (n !== null) {
+      if (!n._deleted) {
+        lastUndeleted = n
+      }
+      n = n._right
+    }
+    this.insertAfter(lastUndeleted, content)
+  }
+
+  /**
+   * Transform this YXml Type to a readable format.
+   * Useful for logging as all Items and Delete implement this method.
+   *
+   * @private
+   */
+  _logString () {
+    return logItemHelper('YArray', this, `start:${logID(this._start)}"`)
+  }
+}

src/Types/YMap/YMap.mjs

@@ -0,0 +1,175 @@
+import Item from '../../Struct/Item.mjs'
+import Type from '../../Struct/Type.mjs'
+import ItemJSON from '../../Struct/ItemJSON.mjs'
+import { logItemHelper } from '../../MessageHandler/messageToString.mjs'
+import YEvent from '../../Util/YEvent.mjs'
+
+/**
+ * Event that describes the changes on a YMap.
+ *
+ * @param {YMap} ymap The YArray that changed.
+ * @param {Set<any>} subs The keys that changed.
+ * @param {boolean} remote Whether the change was created by a remote peer.
+ */
+export class YMapEvent extends YEvent {
+  constructor (ymap, subs, remote) {
+    super(ymap)
+    this.keysChanged = subs
+    this.remote = remote
+  }
+}
+
+/**
+ * A shared Map implementation.
+ */
+export default class YMap extends Type {
+  /**
+   * @private
+   * Creates YMap Event and calls observers.
+   */
+  _callObserver (transaction, parentSubs, remote) {
+    this._callEventHandler(transaction, new YMapEvent(this, parentSubs, remote))
+  }
+
+  /**
+   * Transforms this Shared Type to a JSON object.
+   *
+   * @return {Object}
+   */
+  toJSON () {
+    const map = {}
+    for (let [key, item] of this._map) {
+      if (!item._deleted) {
+        let res
+        if (item instanceof Type) {
+          if (item.toJSON !== undefined) {
+            res = item.toJSON()
+          } else {
+            res = item.toString()
+          }
+        } else {
+          res = item._content[0]
+        }
+        map[key] = res
+      }
+    }
+    return map
+  }
+
+  /**
+   * Returns the keys for each element in the YMap Type.
+   *
+   * @return {Array}
+   */
+  keys () {
+    // TODO: Should return either Iterator or Set!
+    let keys = []
+    for (let [key, value] of this._map) {
+      if (!value._deleted) {
+        keys.push(key)
+      }
+    }
+    return keys
+  }
+
+  /**
+   * Remove a specified element from this YMap.
+   *
+   * @param {encodable} key The key of the element to remove.
+   */
+  delete (key) {
+    this._transact((y) => {
+      let c = this._map.get(key)
+      if (y !== null && c !== undefined) {
+        c._delete(y)
+      }
+    })
+  }
+
+  /**
+   * Adds or updates an element with a specified key and value.
+   *
+   * @param {encodable} key The key of the element to add to this YMap.
+   * @param {encodable | YType} value The value of the element to add to this
+   *                                  YMap.
+   */
+  set (key, value) {
+    this._transact(y => {
+      const old = this._map.get(key) || null
+      if (old !== null) {
+        if (
+          old.constructor === ItemJSON &&
+          !old._deleted && old._content[0] === value
+        ) {
+          // Trying to overwrite with same value
+          // break here
+          return value
+        }
+        if (y !== null) {
+          old._delete(y)
+        }
+      }
+      let v
+      if (typeof value === 'function') {
+        v = new value() // eslint-disable-line new-cap
+        value = v
+      } else if (value instanceof Item) {
+        v = value
+      } else {
+        v = new ItemJSON()
+        v._content = [value]
+      }
+      v._right = old
+      v._right_origin = old
+      v._parent = this
+      v._parentSub = key
+      if (y !== null) {
+        v._integrate(y)
+      } else {
+        this._map.set(key, v)
+      }
+    })
+    return value
+  }
+
+  /**
+   * Returns a specified element from this YMap.
+   *
+   * @param {encodable} key The key of the element to return.
+   */
+  get (key) {
+    let v = this._map.get(key)
+    if (v === undefined || v._deleted) {
+      return undefined
+    }
+    if (v instanceof Type) {
+      return v
+    } else {
+      return v._content[v._content.length - 1]
+    }
+  }
+
+  /**
+   * Returns a boolean indicating whether the specified key exists or not.
+   *
+   * @param {encodable} key The key to test.
+   */
+  has (key) {
+    let v = this._map.get(key)
+    if (v === undefined || v._deleted) {
+      return false
+    } else {
+      return true
+    }
+  }
+
+  /**
+   * Transform this YXml Type to a readable format.
+   * Useful for logging as all Items and Delete implement this method.
+   *
+   * @private
+   */
+  _logString () {
+    return logItemHelper('YMap', this, `mapSize:${this._map.size}`)
+  }
+}

src/Types/YText/YText.mjs

@@ -0,0 +1,656 @@
+import ItemEmbed from '../../Struct/ItemEmbed.mjs'
+import ItemString from '../../Struct/ItemString.mjs'
+import ItemFormat from '../../Struct/ItemFormat.mjs'
+import { logItemHelper } from '../../MessageHandler/messageToString.mjs'
+import { YArrayEvent, default as YArray } from '../YArray/YArray.mjs'
+
+/**
+ * @private
+ */
+function integrateItem (item, parent, y, left, right) {
+  item._origin = left
+  item._left = left
+  item._right = right
+  item._right_origin = right
+  item._parent = parent
+  if (y !== null) {
+    item._integrate(y)
+  } else if (left === null) {
+    parent._start = item
+  } else {
+    left._right = item
+  }
+}
+
+/**
+ * @private
+ */
+function findNextPosition (currentAttributes, parent, left, right, count) {
+  while (right !== null && count > 0) {
+    switch (right.constructor) {
+      case ItemEmbed:
+      case ItemString:
+        const rightLen = right._deleted ? 0 : (right._length - 1)
+        if (count <= rightLen) {
+          right = right._splitAt(parent._y, count)
+          left = right._left
+          return [left, right, currentAttributes]
+        }
+        if (right._deleted === false) {
+          count -= right._length
+        }
+        break
+      case ItemFormat:
+        if (right._deleted === false) {
+          updateCurrentAttributes(currentAttributes, right)
+        }
+        break
+    }
+    left = right
+    right = right._right
+  }
+  return [left, right, currentAttributes]
+}
+
+/**
+ * @private
+ */
+function findPosition (parent, index) {
+  let currentAttributes = new Map()
+  let left = null
+  let right = parent._start
+  return findNextPosition(currentAttributes, parent, left, right, index)
+}
+
+/**
+ * Negate applied formats
+ *
+ * @private
+ */
+function insertNegatedAttributes (y, parent, left, right, negatedAttributes) {
+  // check if we really need to remove attributes
+  while (
+    right !== null && (
+      right._deleted === true || (
+        right.constructor === ItemFormat &&
+        (negatedAttributes.get(right.key) === right.value)
+      )
+    )
+  ) {
+    if (right._deleted === false) {
+      negatedAttributes.delete(right.key)
+    }
+    left = right
+    right = right._right
+  }
+  for (let [key, val] of negatedAttributes) {
+    let format = new ItemFormat()
+    format.key = key
+    format.value = val
+    integrateItem(format, parent, y, left, right)
+    left = format
+  }
+  return [left, right]
+}
+
+/**
+ * @private
+ */
+function updateCurrentAttributes (currentAttributes, item) {
+  const value = item.value
+  const key = item.key
+  if (value === null) {
+    currentAttributes.delete(key)
+  } else {
+    currentAttributes.set(key, value)
+  }
+}
+
+/**
+ * @private
+ */
+function minimizeAttributeChanges (left, right, currentAttributes, attributes) {
+  // go right while attributes[right.key] === right.value (or right is deleted)
+  while (true) {
+    if (right === null) {
+      break
+    } else if (right._deleted === true) {
+      // continue
+    } else if (right.constructor === ItemFormat && (attributes[right.key] || null) === right.value) {
+      // found a format, update currentAttributes and continue
+      updateCurrentAttributes(currentAttributes, right)
+    } else {
+      break
+    }
+    left = right
+    right = right._right
+  }
+  return [left, right]
+}
+
+/**
+ * @private
+ */
+function insertAttributes (y, parent, left, right, attributes, currentAttributes) {
+  const negatedAttributes = new Map()
+  // insert format-start items
+  for (let key in attributes) {
+    const val = attributes[key]
+    const currentVal = currentAttributes.get(key)
+    if (currentVal !== val) {
+      // save negated attribute (set null if currentVal undefined)
+      negatedAttributes.set(key, currentVal || null)
+      let format = new ItemFormat()
+      format.key = key
+      format.value = val
+      integrateItem(format, parent, y, left, right)
+      left = format
+    }
+  }
+  return [left, right, negatedAttributes]
+}
+
+/**
+ * @private
+ */
+function insertText (y, text, parent, left, right, currentAttributes, attributes) {
+  for (let [key] of currentAttributes) {
+    if (attributes[key] === undefined) {
+      attributes[key] = null
+    }
+  }
+  [left, right] = minimizeAttributeChanges(left, right, currentAttributes, attributes)
+  let negatedAttributes
+  [left, right, negatedAttributes] = insertAttributes(y, parent, left, right, attributes, currentAttributes)
+  // insert content
+  let item
+  if (text.constructor === String) {
+    item = new ItemString()
+    item._content = text
+  } else {
+    item = new ItemEmbed()
+    item.embed = text
+  }
+  integrateItem(item, parent, y, left, right)
+  left = item
+  return insertNegatedAttributes(y, parent, left, right, negatedAttributes)
+}
+
+/**
+ * @private
+ */
+function formatText (y, length, parent, left, right, currentAttributes, attributes) {
+  [left, right] = minimizeAttributeChanges(left, right, currentAttributes, attributes)
+  let negatedAttributes
+  [left, right, negatedAttributes] = insertAttributes(y, parent, left, right, attributes, currentAttributes)
+  // iterate until first non-format or null is found
+  // delete all formats with attributes[format.key] != null
+  while (length > 0 && right !== null) {
+    if (right._deleted === false) {
+      switch (right.constructor) {
+        case ItemFormat:
+          const attr = attributes[right.key]
+          if (attr !== undefined) {
+            if (attr === right.value) {
+              negatedAttributes.delete(right.key)
+            } else {
+              negatedAttributes.set(right.key, right.value)
+            }
+            right._delete(y)
+          }
+          updateCurrentAttributes(currentAttributes, right)
+          break
+        case ItemEmbed:
+        case ItemString:
+          right._splitAt(y, length)
+          length -= right._length
+          break
+      }
+    }
+    left = right
+    right = right._right
+  }
+  return insertNegatedAttributes(y, parent, left, right, negatedAttributes)
+}
+
+/**
+ * @private
+ */
+function deleteText (y, length, parent, left, right, currentAttributes) {
+  while (length > 0 && right !== null) {
+    if (right._deleted === false) {
+      switch (right.constructor) {
+        case ItemFormat:
+          updateCurrentAttributes(currentAttributes, right)
+          break
+        case ItemEmbed:
+        case ItemString:
+          right._splitAt(y, length)
+          length -= right._length
+          right._delete(y)
+          break
+      }
+    }
+    left = right
+    right = right._right
+  }
+  return [left, right]
+}
+
+// TODO: In the quill delta representation we should also use the format {ops:[..]}
+/**
+ * The Quill Delta format represents changes on a text document with
+ * formatting information. For mor information visit {@link https://quilljs.com/docs/delta/|Quill Delta}
+ *
+ * @example
+ *   {
+ *     ops: [
+ *       { insert: 'Gandalf', attributes: { bold: true } },
+ *       { insert: ' the ' },
+ *       { insert: 'Grey', attributes: { color: '#cccccc' } }
+ *     ]
+ *   }
+ *
+ * @typedef {Array<Object>} Delta
+ */
+
+ /**
+  * Attributes that can be assigned to a selection of text.
+  *
+  * @example
+  *   {
+  *     bold: true,
+  *     font-size: '40px'
+  *   }
+  *
+  * @typedef {Object} TextAttributes
+  */
+
+/**
+ * Event that describes the changes on a YText type.
+ *
+ * @private
+ */
+class YTextEvent extends YArrayEvent {
+  constructor (ytext, remote, transaction) {
+    super(ytext, remote, transaction)
+    this._delta = null
+  }
+  // TODO: Should put this in a separate function. toDelta shouldn't be included
+  //       in every Yjs distribution
+  /**
+   * Compute the changes in the delta format.
+   *
+   * @return {Delta} A {@link https://quilljs.com/docs/delta/|Quill Delta}) that
+   *                 represents the changes on the document.
+   *
+   * @public
+   */
+  get delta () {
+    if (this._delta === null) {
+      const y = this.target._y
+      y.transact(() => {
+        let item = this.target._start
+        const delta = []
+        const added = this.addedElements
+        const removed = this.removedElements
+        this._delta = delta
+        let action = null
+        let attributes = {} // counts added or removed new attributes for retain
+        const currentAttributes = new Map() // saves all current attributes for insert
+        const oldAttributes = new Map()
+        let insert = ''
+        let retain = 0
+        let deleteLen = 0
+        const addOp = function addOp () {
+          if (action !== null) {
+            let op
+            switch (action) {
+              case 'delete':
+                op = { delete: deleteLen }
+                deleteLen = 0
+                break
+              case 'insert':
+                op = { insert }
+                if (currentAttributes.size > 0) {
+                  op.attributes = {}
+                  for (let [key, value] of currentAttributes) {
+                    if (value !== null) {
+                      op.attributes[key] = value
+                    }
+                  }
+                }
+                insert = ''
+                break
+              case 'retain':
+                op = { retain }
+                if (Object.keys(attributes).length > 0) {
+                  op.attributes = {}
+                  for (let key in attributes) {
+                    op.attributes[key] = attributes[key]
+                  }
+                }
+                retain = 0
+                break
+            }
+            delta.push(op)
+            action = null
+          }
+        }
+        while (item !== null) {
+          switch (item.constructor) {
+            case ItemEmbed:
+              if (added.has(item)) {
+                addOp()
+                action = 'insert'
+                insert = item.embed
+                addOp()
+              } else if (removed.has(item)) {
+                if (action !== 'delete') {
+                  addOp()
+                  action = 'delete'
+                }
+                deleteLen += 1
+              } else if (item._deleted === false) {
+                if (action !== 'retain') {
+                  addOp()
+                  action = 'retain'
+                }
+                retain += 1
+              }
+              break
+            case ItemString:
+              if (added.has(item)) {
+                if (action !== 'insert') {
+                  addOp()
+                  action = 'insert'
+                }
+                insert += item._content
+              } else if (removed.has(item)) {
+                if (action !== 'delete') {
+                  addOp()
+                  action = 'delete'
+                }
+                deleteLen += item._length
+              } else if (item._deleted === false) {
+                if (action !== 'retain') {
+                  addOp()
+                  action = 'retain'
+                }
+                retain += item._length
+              }
+              break
+            case ItemFormat:
+              if (added.has(item)) {
+                const curVal = currentAttributes.get(item.key) || null
+                if (curVal !== item.value) {
+                  if (action === 'retain') {
+                    addOp()
+                  }
+                  if (item.value === (oldAttributes.get(item.key) || null)) {
+                    delete attributes[item.key]
+                  } else {
+                    attributes[item.key] = item.value
+                  }
+                } else {
+                  item._delete(y)
+                }
+              } else if (removed.has(item)) {
+                oldAttributes.set(item.key, item.value)
+                const curVal = currentAttributes.get(item.key) || null
+                if (curVal !== item.value) {
+                  if (action === 'retain') {
+                    addOp()
+                  }
+                  attributes[item.key] = curVal
+                }
+              } else if (item._deleted === false) {
+                oldAttributes.set(item.key, item.value)
+                const attr = attributes[item.key]
+                if (attr !== undefined) {
+                  if (attr !== item.value) {
+                    if (action === 'retain') {
+                      addOp()
+                    }
+                    if (item.value === null) {
+                      attributes[item.key] = item.value
+                    } else {
+                      delete attributes[item.key]
+                    }
+                  } else {
+                    item._delete(y)
+                  }
+                }
+              }
+              if (item._deleted === false) {
+                if (action === 'insert') {
+                  addOp()
+                }
+                updateCurrentAttributes(currentAttributes, item)
+              }
+              break
+          }
+          item = item._right
+        }
+        addOp()
+        while (this._delta.length > 0) {
+          let lastOp = this._delta[this._delta.length - 1]
+          if (lastOp.retain !== undefined && lastOp.attributes === undefined) {
+            // retain delta's if they don't assign attributes
+            this._delta.pop()
+          } else {
+            break
+          }
+        }
+      })
+    }
+    return this._delta
+  }
+}
+
+/**
+ * Type that represents text with formatting information.
+ *
+ * This type replaces y-richtext as this implementation is able to handle
+ * block formats (format information on a paragraph), embeds (complex elements
+ * like pictures and videos), and text formats (**bold**, *italic*).
+ *
+ * @param {String} string The initial value of the YText.
+ */
+export default class YText extends YArray {
+  constructor (string) {
+    super()
+    if (typeof string === 'string') {
+      const start = new ItemString()
+      start._parent = this
+      start._content = string
+      this._start = start
+    }
+  }
+
+  /**
+   * @private
+   * Creates YMap Event and calls observers.
+   */
+  _callObserver (transaction, parentSubs, remote) {
+    this._callEventHandler(transaction, new YTextEvent(this, remote, transaction))
+  }
+
+  /**
+   * Returns the unformatted string representation of this YText type.
+   *
+   * @public
+   */
+  toString () {
+    let str = ''
+    let n = this._start
+    while (n !== null) {
+      if (!n._deleted && n._countable) {
+        str += n._content
+      }
+      n = n._right
+    }
+    return str
+  }
+
+  /**
+   * Apply a {@link Delta} on this shared YText type.
+   *
+   * @param {Delta} delta The changes to apply on this element.
+   *
+   * @public
+   */
+  applyDelta (delta) {
+    this._transact(y => {
+      let left = null
+      let right = this._start
+      const currentAttributes = new Map()
+      for (let i = 0; i < delta.length; i++) {
+        let op = delta[i]
+        if (op.insert !== undefined) {
+          ;[left, right] = insertText(y, op.insert, this, left, right, currentAttributes, op.attributes || {})
+        } else if (op.retain !== undefined) {
+          ;[left, right] = formatText(y, op.retain, this, left, right, currentAttributes, op.attributes || {})
+        } else if (op.delete !== undefined) {
+          ;[left, right] = deleteText(y, op.delete, this, left, right, currentAttributes)
+        }
+      }
+    })
+  }
+
+  /**
+   * Returns the Delta representation of this YText type.
+   *
+   * @return {Delta} The Delta representation of this type.
+   *
+   * @public
+   */
+  toDelta () {
+    let ops = []
+    let currentAttributes = new Map()
+    let str = ''
+    let n = this._start
+    function packStr () {
+      if (str.length > 0) {
+        // pack str with attributes to ops
+        let attributes = {}
+        let addAttributes = false
+        for (let [key, value] of currentAttributes) {
+          addAttributes = true
+          attributes[key] = value
+        }
+        let op = { insert: str }
+        if (addAttributes) {
+          op.attributes = attributes
+        }
+        ops.push(op)
+        str = ''
+      }
+    }
+    while (n !== null) {
+      if (!n._deleted) {
+        switch (n.constructor) {
+          case ItemString:
+            str += n._content
+            break
+          case ItemFormat:
+            packStr()
+            updateCurrentAttributes(currentAttributes, n)
+            break
+        }
+      }
+      n = n._right
+    }
+    packStr()
+    return ops
+  }
+
+  /**
+   * Insert text at a given index.
+   *
+   * @param {Integer} index The index at which to start inserting.
+   * @param {String} text The text to insert at the specified position.
+   * @param {TextAttributes} attributes Optionally define some formatting
+   *                                    information to apply on the inserted
+   *                                    Text.
+   *
+   * @public
+   */
+  insert (index, text, attributes = {}) {
+    if (text.length <= 0) {
+      return
+    }
+    this._transact(y => {
+      let [left, right, currentAttributes] = findPosition(this, index)
+      insertText(y, text, this, left, right, currentAttributes, attributes)
+    })
+  }
+
+  /**
+   * Inserts an embed at a index.
+   *
+   * @param {Integer} index The index to insert the embed at.
+   * @param {Object} embed The Object that represents the embed.
+   * @param {TextAttributes} attributes Attribute information to apply on the
+   *                                    embed
+   *
+   * @public
+   */
+  insertEmbed (index, embed, attributes = {}) {
+    if (embed.constructor !== Object) {
+      throw new Error('Embed must be an Object')
+    }
+    this._transact(y => {
+      let [left, right, currentAttributes] = findPosition(this, index)
+      insertText(y, embed, this, left, right, currentAttributes, attributes)
+    })
+  }
+
+  /**
+   * Deletes text starting from an index.
+   *
+   * @param {Integer} index Index at which to start deleting.
+   * @param {Integer} length The number of characters to remove. Defaults to 1.
+   *
+   * @public
+   */
+  delete (index, length) {
+    if (length === 0) {
+      return
+    }
+    this._transact(y => {
+      let [left, right, currentAttributes] = findPosition(this, index)
+      deleteText(y, length, this, left, right, currentAttributes)
+    })
+  }
+
+  /**
+   * Assigns properties to a range of text.
+   *
+   * @param {Integer} index The position where to start formatting.
+   * @param {Integer} length The amount of characters to assign properties to.
+   * @param {TextAttributes} attributes Attribute information to apply on the
+   *                                    text.
+   *
+   * @public
+   */
+  format (index, length, attributes) {
+    this._transact(y => {
+      let [left, right, currentAttributes] = findPosition(this, index)
+      if (right === null) {
+        return
+      }
+      formatText(y, length, this, left, right, currentAttributes, attributes)
+    })
+  }
+  // TODO: De-duplicate code. The following code is in every type.
+  /**
+   * Transform this YText to a readable format.
+   * Useful for logging as all Items implement this method.
+   *
+   * @private
+   */
+  _logString () {
+    return logItemHelper('YText', this)
+  }
+}

src/Types/YXml/YXmlElement.mjs

@@ -0,0 +1,190 @@
+import YMap from '../YMap/YMap.mjs'
+import YXmlFragment from './YXmlFragment.mjs'
+import { createAssociation } from '../../Bindings/DomBinding/util.mjs'
+
+/**
+ * An YXmlElement imitates the behavior of a
+ * {@link https://developer.mozilla.org/en-US/docs/Web/API/Element|Dom Element}.
+ *
+ * * An YXmlElement has attributes (key value pairs)
+ * * An YXmlElement has childElements that must inherit from YXmlElement
+ *
+ * @param {String} nodeName Node name
+ */
+export default class YXmlElement extends YXmlFragment {
+  constructor (nodeName = 'UNDEFINED') {
+    super()
+    this.nodeName = nodeName.toUpperCase()
+  }
+
+  /**
+   * @private
+   * Creates an Item with the same effect as this Item (without position effect)
+   */
+  _copy () {
+    let struct = super._copy()
+    struct.nodeName = this.nodeName
+    return struct
+  }
+
+  /**
+   * @private
+   * Read the next Item in a Decoder and fill this Item with the read data.
+   *
+   * This is called when data is received from a remote peer.
+   *
+   * @param {Y} y The Yjs instance that this Item belongs to.
+   * @param {BinaryDecoder} decoder The decoder object to read data from.
+   */
+  _fromBinary (y, decoder) {
+    const missing = super._fromBinary(y, decoder)
+    this.nodeName = decoder.readVarString()
+    return missing
+  }
+
+  /**
+   * 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.
+   *
+   * @param {BinaryEncoder} encoder The encoder to write data to.
+   *
+   * @private
+   */
+  _toBinary (encoder) {
+    super._toBinary(encoder)
+    encoder.writeVarString(this.nodeName)
+  }
+
+  /**
+   * Integrates this Item into the shared structure.
+   *
+   * This method actually applies the change to the Yjs instance. In case of
+   * Item it connects _left and _right to this Item and calls the
+   * {@link Item#beforeChange} method.
+   *
+   * * Checks for nodeName
+   * * Sets domFilter
+   *
+   * @param {Y} y The Yjs instance
+   *
+   * @private
+   */
+  _integrate (y) {
+    if (this.nodeName === null) {
+      throw new Error('nodeName must be defined!')
+    }
+    super._integrate(y)
+  }
+
+  /**
+   * Returns the string representation 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.
+   *
+   * @public
+   */
+  toString () {
+    const attrs = this.getAttributes()
+    const stringBuilder = []
+    const keys = []
+    for (let key in attrs) {
+      keys.push(key)
+    }
+    keys.sort()
+    const keysLen = keys.length
+    for (let i = 0; i < keysLen; i++) {
+      const key = keys[i]
+      stringBuilder.push(key + '="' + attrs[key] + '"')
+    }
+    const nodeName = this.nodeName.toLocaleLowerCase()
+    const attrsString = stringBuilder.length > 0 ? ' ' + stringBuilder.join(' ') : ''
+    return `<${nodeName}${attrsString}>${super.toString()}</${nodeName}>`
+  }
+
+  /**
+   * Removes an attribute from this YXmlElement.
+   *
+   * @param {String} attributeName The attribute name that is to be removed.
+   *
+   * @public
+   */
+  removeAttribute (attributeName) {
+    return YMap.prototype.delete.call(this, attributeName)
+  }
+
+  /**
+   * Sets or updates an attribute.
+   *
+   * @param {String} attributeName The attribute name that is to be set.
+   * @param {String} attributeValue The attribute value that is to be set.
+   *
+   * @public
+   */
+  setAttribute (attributeName, attributeValue) {
+    return YMap.prototype.set.call(this, attributeName, attributeValue)
+  }
+
+  /**
+   * Returns an attribute value that belongs to the attribute name.
+   *
+   * @param {String} attributeName The attribute name that identifies the
+   *                               queried value.
+   * @return {String} The queried attribute value.
+   *
+   * @public
+   */
+  getAttribute (attributeName) {
+    return YMap.prototype.get.call(this, attributeName)
+  }
+
+  /**
+   * Returns all attribute name/value pairs in a JSON Object.
+   *
+   * @return {Object} A JSON Object that describes the attributes.
+   *
+   * @public
+   */
+  getAttributes () {
+    const obj = {}
+    for (let [key, value] of this._map) {
+      if (!value._deleted) {
+        obj[key] = value._content[0]
+      }
+    }
+    return obj
+  }
+  // TODO: outsource the binding property.
+  /**
+   * 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<key:hookDefinition>} [hooks={}] Optional property to customize how hooks
+   *                                             are presented in the DOM
+   * @param {DomBinding} [binding] You should not set this property. This is
+   *                               used if DomBinding wants to create a
+   *                               association to the created DOM type.
+   * @return {Element} The {@link https://developer.mozilla.org/en-US/docs/Web/API/Element|Dom Element}
+   *
+   * @public
+   */
+  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])
+    }
+    this.forEach(yxml => {
+      dom.appendChild(yxml.toDom(_document, hooks, binding))
+    })
+    createAssociation(binding, dom, this)
+    return dom
+  }
+}
+
+YXmlFragment._YXmlElement = YXmlElement

src/Types/YXml/YXmlEvent.mjs

@@ -0,0 +1,47 @@
+import YEvent from '../../Util/YEvent.mjs'
+
+/**
+ * An Event that describes changes on a YXml Element or Yxml Fragment
+ *
+ * @protected
+ */
+export default class YXmlEvent extends YEvent {
+  /**
+   * @param {YType} target The target on which the event is created.
+   * @param {Set} subs The set of changed attributes. `null` is included if the
+   *                   child list changed.
+   * @param {Boolean} remote Whether this change was created by a remote peer.
+   * @param {Transaction} transaction The transaction instance with wich the
+   *                                  change was created.
+   */
+  constructor (target, subs, remote, transaction) {
+    super(target)
+    /**
+     * The transaction instance for the computed change.
+     * @type {Transaction}
+     */
+    this._transaction = transaction
+    /**
+     * Whether the children changed.
+     * @type {Boolean}
+     */
+    this.childListChanged = false
+    /**
+     * Set of all changed attributes.
+     * @type {Set}
+     */
+    this.attributesChanged = new Set()
+    /**
+     * Whether this change was created by a remote peer.
+     * @type {Boolean}
+     */
+    this.remote = remote
+    subs.forEach((sub) => {
+      if (sub === null) {
+        this.childListChanged = true
+      } else {
+        this.attributesChanged.add(sub)
+      }
+    })
+  }
+}

src/Types/YXml/YXmlFragment.mjs

@@ -0,0 +1,167 @@
+import { createAssociation } from '../../Bindings/DomBinding/util.mjs'
+import YXmlTreeWalker from './YXmlTreeWalker.mjs'
+
+import YArray from '../YArray/YArray.mjs'
+import YXmlEvent from './YXmlEvent.mjs'
+import { logItemHelper } from '../../MessageHandler/messageToString.mjs'
+
+/**
+ * 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.
+ */
+
+/**
+ * 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
+ */
+
+/**
+ * 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
+ */
+export default class YXmlFragment extends YArray {
+  /**
+   * 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} 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 {TreeWalker} 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} The first element that matches the query or null.
+   *
+   * @public
+   */
+  querySelector (query) {
+    query = query.toUpperCase()
+    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>} The elements that match this query.
+   *
+   * @public
+   */
+  querySelectorAll (query) {
+    query = query.toUpperCase()
+    return Array.from(new YXmlTreeWalker(this, element => element.nodeName === query))
+  }
+
+  /**
+   * Creates YArray Event and calls observers.
+   *
+   * @private
+   */
+  _callObserver (transaction, parentSubs, remote) {
+    this._callEventHandler(transaction, new YXmlEvent(this, parentSubs, remote, transaction))
+  }
+
+  /**
+   * Get the string representation of all the children of this YXmlFragment.
+   *
+   * @return {string} The string representation of all children.
+   */
+  toString () {
+    return this.map(xml => xml.toString()).join('')
+  }
+
+  /**
+   * @private
+   * Unbind from Dom and mark this Item as deleted.
+   *
+   * @param {Y} y The Yjs instance
+   * @param {boolean} createDelete Whether to propagate a message that this
+   *                               Type was deleted.
+   * @param {boolean} [gcChildren=y._hasUndoManager===false] Whether to garbage
+   *                                         collect the children of this type.
+   *
+   * @private
+   */
+  _delete (y, createDelete, gcChildren) {
+    super._delete(y, createDelete, gcChildren)
+  }
+
+  /**
+   * 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<key:hookDefinition>} [hooks={}] Optional property to customize how hooks
+   *                                             are presented in the DOM
+   * @param {DomBinding} [binding] You should not set this property. This is
+   *                               used if DomBinding wants to create a
+   *                               association to the created DOM type
+   * @return {Element} The {@link https://developer.mozilla.org/en-US/docs/Web/API/Element|Dom Element}
+   *
+   * @public
+   */
+  toDom (_document = document, hooks = {}, binding) {
+    const fragment = _document.createDocumentFragment()
+    createAssociation(binding, fragment, this)
+    this.forEach(xmlType => {
+      fragment.insertBefore(xmlType.toDom(_document, hooks, binding), null)
+    })
+    return fragment
+  }
+  /**
+   * Transform this YXml Type to a readable format.
+   * Useful for logging as all Items and Delete implement this method.
+   *
+   * @private
+   */
+  _logString () {
+    return logItemHelper('YXml', this)
+  }
+}

src/Types/YXml/YXmlHook.mjs

@@ -0,0 +1,108 @@
+import YMap from '../YMap/YMap.mjs'
+import { createAssociation } from '../../Bindings/DomBinding/util.mjs'
+
+/**
+ * You can manage binding to a custom type with YXmlHook.
+ *
+ * @public
+ */
+export default class YXmlHook extends YMap {
+  /**
+   * @param {String} hookName nodeName of the Dom Node.
+   */
+  constructor (hookName) {
+    super()
+    this.hookName = null
+    if (hookName !== undefined) {
+      this.hookName = hookName
+    }
+  }
+
+  /**
+   * Creates an Item with the same effect as this Item (without position effect)
+   *
+   * @private
+   */
+  _copy () {
+    const struct = super._copy()
+    struct.hookName = this.hookName
+    return struct
+  }
+
+  /**
+   * 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<key:hookDefinition>} [hooks] Optional property to customize how hooks
+   *                                             are presented in the DOM
+   * @param {DomBinding} [binding] You should not set this property. This is
+   *                               used if DomBinding wants to create a
+   *                               association to the created DOM type
+   * @return {Element} The {@link https://developer.mozilla.org/en-US/docs/Web/API/Element|Dom Element}
+   *
+   * @public
+   */
+  toDom (_document = document, hooks = {}, binding) {
+    const hook = hooks[this.hookName]
+    let dom
+    if (hook !== undefined) {
+      dom = hook.createDom(this)
+    } else {
+      dom = document.createElement(this.hookName)
+    }
+    dom.setAttribute('data-yjs-hook', this.hookName)
+    createAssociation(binding, dom, this)
+    return dom
+  }
+
+  /**
+   * Read the next Item in a Decoder and fill this Item with the read data.
+   *
+   * This is called when data is received from a remote peer.
+   *
+   * @param {Y} y The Yjs instance that this Item belongs to.
+   * @param {BinaryDecoder} decoder The decoder object to read data from.
+   *
+   * @private
+   */
+  _fromBinary (y, decoder) {
+    const missing = super._fromBinary(y, decoder)
+    this.hookName = decoder.readVarString()
+    return missing
+  }
+
+  /**
+   * 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.
+   *
+   * @param {BinaryEncoder} encoder The encoder to write data to.
+   *
+   * @private
+   */
+  _toBinary (encoder) {
+    super._toBinary(encoder)
+    encoder.writeVarString(this.hookName)
+  }
+
+  /**
+   * 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 {Y} y The Yjs instance
+   *
+   * @private
+   */
+  _integrate (y) {
+    if (this.hookName === null) {
+      throw new Error('hookName must be defined!')
+    }
+    super._integrate(y)
+  }
+}

src/Types/YXml/YXmlText.mjs

@@ -0,0 +1,46 @@
+import YText from '../YText/YText.mjs'
+import { createAssociation } from '../../Bindings/DomBinding/util.mjs'
+
+/**
+ * Represents text in a Dom Element. In the future this type will also handle
+ * simple formatting information like bold and italic.
+ *
+ * @param {String} arg1 Initial value.
+ */
+export default class YXmlText extends YText {
+  /**
+   * Creates a Dom Element that mirrors this YXmlText.
+   *
+   * @param {Document} [_document=document] The document object (you must define
+   *                                        this when calling this method in
+   *                                        nodejs)
+   * @param {Object<key:hookDefinition>} [hooks] Optional property to customize how hooks
+   *                                             are presented in the DOM
+   * @param {DomBinding} [binding] You should not set this property. This is
+   *                               used if DomBinding wants to create a
+   *                               association to the created DOM type.
+   * @return {Element} The {@link https://developer.mozilla.org/en-US/docs/Web/API/Element|Dom Element}
+   *
+   * @public
+   */
+  toDom (_document = document, hooks, binding) {
+    const dom = _document.createTextNode(this.toString())
+    createAssociation(binding, dom, this)
+    return dom
+  }
+
+  /**
+   * Mark this Item as deleted.
+   *
+   * @param {Y} y The Yjs instance
+   * @param {boolean} createDelete Whether to propagate a message that this
+   *                               Type was deleted.
+   * @param {boolean} [gcChildren=y._hasUndoManager===false] Whether to garbage
+   *                                         collect the children of this type.
+   *
+   * @private
+   */
+  _delete (y, createDelete, gcChildren) {
+    super._delete(y, createDelete, gcChildren)
+  }
+}