Merge pull request #702 from kapv89/patch-1

Update README.md to add https://github.com/kapv89/k_yrs_go to persistence providers
2025-03-26 12:57:27 +01:00 · 2025-03-26 01:55:02 +05:30 · 2025-03-18 20:18:35 +01:00 · 2025-03-18 19:23:51 +01:00 · 2025-03-09 20:57:52 +01:00 · 2025-03-06 10:36:18 +01:00
59 changed files with 5373 additions and 4341 deletions
--- a/.github/workflows/node.js.yml
+++ b/.github/workflows/node.js.yml
@ -16,14 +16,16 @@ jobs:

    strategy:
      matrix:
-        node-version: [10.x, 12.x, 14.x]
+        node-version: [16.x, 20.x]

    steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
    - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v1
+      uses: actions/setup-node@v3
      with:
        node-version: ${{ matrix.node-version }}
    - run: npm ci
-    - run: npm run build --if-present
-    - run: npm test
+    - run: npm run lint
+    - run: npm run test
+      env:
+        CI: true
--- a/.github/workflows/nodejs.yml
+++ b/.github/workflows/nodejs.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: [ master ]
-  pull_request:
-    branches: [ master ]
-
-jobs:
-  build:
-
-    runs-on: ubuntu-latest
-
-    strategy:
-      matrix:
-        node-version: [10.x, 12.x, 13.x]
-
-    steps:
-    - uses: actions/checkout@v2
-    - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v1
-      with:
-        node-version: ${{ matrix.node-version }}
-    - run: npm ci
-    - run: npm run lint
-    - run: npm run test-extensive
-      env:
-        CI: true
--- a/INTERNALS.md
+++ b/INTERNALS.md
@ -26,7 +26,7 @@ article](https://blog.kevinjahns.de/are-crdts-suitable-for-shared-editing/).

 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).
+range \[JavaScript uses IEEE 754 floats\]).

 ## List items

@ -60,7 +60,7 @@ 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 preceeding and
+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
@ -88,7 +88,7 @@ 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 10 most recently looked up
+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
@ -149,8 +149,8 @@ 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 updates that allows clients to sync with each other.
-The update object is an Uint8Array that efficiently encodes `Item` objects and
+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
--- a/4
+++ b/4
@ -1,7 +1,7 @@
 The MIT License (MIT)

-Copyright (c) 2014
-  - Kevin Jahns <kevin.jahns@rwth-aachen.de>.
+Copyright (c) 2023
+  - Kevin Jahns <kevin.jahns@protonmail.com>.
  - 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
--- a/README.md
+++ b/README.md
@ -3,7 +3,7 @@

 > A CRDT framework with a powerful abstraction of shared data

-Yjs is a [CRDT implementation](#Yjs-CRDT-Algorithm) that exposes its internal
+Yjs is a [CRDT implementation](#yjs-crdt-algorithm) that exposes its internal
 data structure as *shared types*. Shared types are common data types like `Map`
 or `Array` with superpowers: changes are automatically distributed to other
 peers and merged without merge conflicts.
@ -32,13 +32,34 @@ Otherwise you can find help on our community [discussion board](https://discuss.
 Please contribute to the project financially - especially if your company relies
 on Yjs. [![Become a Sponsor](https://img.shields.io/static/v1?label=Become%20a%20Sponsor&message=%E2%9D%A4&logo=GitHub&style=flat&color=d42f2d)](https://github.com/sponsors/dmonad)

+## Professional Support
+
+* [Support Contract with the Maintainer](https://github.com/sponsors/dmonad) -
+By contributing financially to the open-source Yjs project, you can receive
+professional support directly from the author. This includes the opportunity for
+weekly video calls to discuss your specific challenges.
+* [Synergy Codes](https://synergycodes.com/yjs-services/) - Specializing in
+consulting and developing real-time collaborative editing solutions for visual
+apps, Synergy Codes focuses on interactive diagrams, complex graphs, charts, and
+various data visualization types. Their expertise empowers developers to build
+engaging and interactive visual experiences leveraging the power of Yjs. See
+their work in action at [Visual Collaboration
+Showcase](https://yjs-diagram.synergy.codes/).
+
 ## Who is using Yjs

-* [Sana](https://sanalabs.com/) A learning platform with collaborative text
-  editing powered by Yjs.
 * [AFFiNE](https://affine.pro/) A local-first, privacy-first, open source
-  knowledge base. 🏅
-* [Dynaboard](https://dynaboard.com/) Build web apps collaboratively. :star2:
+  knowledge base. :star2:
+* [Huly](https://huly.io/) - Open Source All-in-One Project Management Platform :star2:
+* [Cargo](https://cargo.site/) Site builder for designers and artists :star2:
+* [Gitbook](https://gitbook.com) Knowledge management for technical teams :star2:
+* [Evernote](https://evernote.com) Note-taking app :star2:
+* [Lessonspace](https://thelessonspace.com) Enterprise platform for virtual
+  classrooms and online training :star2:
+* [Ellipsus](ellipsus.com) - Collaborative writing app for storytelling etc.
+  Supports versioning, change attribution, and "blame". A solution for the whole
+  publishing process (also selling) :star:
+* [Dynaboard](https://dynaboard.com/) Build web apps collaboratively. :star:
 * [Relm](https://www.relm.us/) A collaborative gameworld for teamwork and
  community. :star:
 * [Room.sh](https://room.sh/) A meeting application with integrated
@ -47,32 +68,78 @@ on Yjs. [![Become a Sponsor](https://img.shields.io/static/v1?label=Become%20a%2
  Nimbus Web. :star:
 * [Pluxbox RadioManager](https://getradiomanager.com/) A web-based app to
  collaboratively organize radio broadcasts. :star:
+* [modyfi](https://www.modyfi.com) - Modyfi is the design platform built for
+  multidisciplinary designers. Design, generate, animate, and more — without
+  switching between apps. :star:
+* [Sana](https://sanalabs.com/) A learning platform with collaborative text
+  editing powered by Yjs.
 * [Serenity Notes](https://www.serenity.re/en/notes) End-to-end encrypted
  collaborative notes app.
-* [PRSM](https://prsm.uk/) Collaborative mind-mapping and system visualisation. *[(source)](https://github.com/micrology/prsm)*
+* [PRSM](https://prsm.uk/) Collaborative mind-mapping and system visualisation.
+  *[(source)](https://github.com/micrology/prsm)*
 * [Alldone](https://alldone.app/) A next-gen project management and
  collaboration platform.
 * [Living Spec](https://livingspec.com/) A modern way for product teams to collaborate.
 * [Slidebeamer](https://slidebeamer.com/) Presentation app.
 * [BlockSurvey](https://blocksurvey.io) End-to-end encryption for your forms/surveys.
 * [Skiff](https://skiff.org/) Private, decentralized workspace.
+* [JupyterLab](https://jupyter.org/) Collaborative computational Notebooks
+* [JupyterCad](https://jupytercad.readthedocs.io/en/latest/) Extension to
+  JupyterLab that enables collaborative editing of 3d FreeCAD Models.
 * [Hyperquery](https://hyperquery.ai/) A collaborative data workspace for
  sharing analyses, documentation, spreadsheets, and dashboards.
+* [Nosgestesclimat](https://nosgestesclimat.fr/groupe) The french carbon
+  footprint calculator has a group P2P mode based on yjs
+* [oorja.io](https://oorja.io) Online meeting spaces extensible with
+  collaborative apps, end-to-end encrypted.
+* [LegendKeeper](https://legendkeeper.com) Collaborative campaign planner and
+  worldbuilding app for tabletop RPGs.
+* [IllumiDesk](https://illumidesk.com/) Build courses and content with A.I.
+* [btw](https://www.btw.so) Open-source Medium alternative
+* [AWS SageMaker](https://aws.amazon.com/sagemaker/) Tools for building Machine
+  Learning Models
+* [linear](https://linear.app) Streamline issues, projects, and product roadmaps.
+* [AWS SageMaker](https://aws.amazon.com/sagemaker/) - Machine Learning Service
+* [Arkiter](https://www.arkiter.com/) - Live interview software
+* [Appflowy](https://www.appflowy.io/) - They use Yrs
+* [Multi.app](https://multi.app) - Multiplayer app sharing: Point, draw and edit
+  in shared apps as if they're on your computer. They are using Yrs.
+* [AppMaster](https://appmaster.io) A No-Code platform for creating
+  production-ready applications with source code generation.
+* [Synthesia](https://www.synthesia.io) - Collaborative Video Editor
+* [thinkdeli](https://thinkdeli.com) - A fast and simple notes app powered by AI
+* [ourboard](https://github.com/raimohanska/ourboard) - A collaborative whiteboard
+  application
+* [Ellie.ai](https://ellie.ai) - Data Product Design and Collaboration
+* [GoPeer](https://gopeer.org/) - Collaborative tutoring
+* [screen.garden](https://screen.garden) - Collaborative backend for PKM apps.
+* [NextCloud](https://nextcloud.com/) - Content Collaboration Platform
+* [keystatic](https://github.com/Thinkmill/keystatic) - git-based CMS
+* [QDAcity](https://qdacity.com) - Collaborative qualitative data analysis platform
+* [Kanbert](https://kanbert.com) - Project management software
+* [Eclipse Theia](https://github.com/eclipse-theia/theia) - A cloud & desktop
+  IDE that runs in the browser.
+* [ScienHub](https://scienhub.com) - Collaborative LaTeX editor in the browser.
+* [Open Collaboration Tools](https://www.open-collab.tools/) - Collaborative
+editing for your IDE or custom editor
+* [Typst](https://typst.app/) - Compose, edit, and automate technical documents

 ## Table of Contents

-* [Overview](#Overview)
-  * [Bindings](#Bindings)
-  * [Providers](#Providers)
-* [Getting Started](#Getting-Started)
-* [API](#API)
-  * [Shared Types](#Shared-Types)
-  * [Y.Doc](#YDoc)
-  * [Document Updates](#Document-Updates)
-  * [Relative Positions](#Relative-Positions)
-  * [Y.UndoManager](#YUndoManager)
-* [Yjs CRDT Algorithm](#Yjs-CRDT-Algorithm)
-* [License and Author](#License-and-Author)
+* [Overview](#overview)
+  * [Bindings](#bindings)
+  * [Providers](#providers)
+  * [Tooling](#tooling)
+  * [Ports](#ports)
+* [Getting Started](#getting-started)
+* [API](#api)
+  * [Shared Types](#shared-types)
+  * [Y.Doc](#ydoc)
+  * [Document Updates](#document-updates)
+  * [Relative Positions](#relative-positions)
+  * [Y.UndoManager](#yundomanager)
+* [Yjs CRDT Algorithm](#yjs-crdt-algorithm)
+* [License and Author](#license-and-author)

 ## Overview

@ -89,9 +156,15 @@ are implemented in separate modules.
 | [CodeMirror](https://codemirror.net/) | ✔ | [y-codemirror](https://github.com/yjs/y-codemirror) | [demo](https://demos.yjs.dev/codemirror/codemirror.html) |
 | [Monaco](https://microsoft.github.io/monaco-editor/) | ✔ | [y-monaco](https://github.com/yjs/y-monaco) | [demo](https://demos.yjs.dev/monaco/monaco.html) |
 | [Slate](https://github.com/ianstormtaylor/slate) | ✔ | [slate-yjs](https://github.com/bitphinix/slate-yjs) | [demo](https://bitphinix.github.io/slate-yjs-example) |
+| [BlockSuite](https://github.com/toeverything/blocksuite) | ✔ | (native) | [demo](https://blocksuite-toeverything.vercel.app/?init) |
+| [Lexical](https://lexical.dev/) | ✔ | (native) | [demo](https://lexical.dev/docs/collaboration/react#see-it-in-action) |
 | [valtio](https://github.com/pmndrs/valtio) |  | [valtio-yjs](https://github.com/dai-shi/valtio-yjs) | [demo](https://codesandbox.io/s/valtio-yjs-demo-ox3iy) |
 | [immer](https://github.com/immerjs/immer) |  | [immer-yjs](https://github.com/sep2/immer-yjs) | [demo](https://codesandbox.io/s/immer-yjs-demo-6e0znb) |
+| React | | [react-yjs](https://github.com/nikgraf/react-yjs) | [demo](https://react-yjs-example.vercel.app/) |
 | React / Vue / Svelte / MobX | | [SyncedStore](https://syncedstore.org) | [demo](https://syncedstore.org/docs/react) |
+| [mobx-keystone](https://mobx-keystone.js.org/) |  | [mobx-keystone-yjs](https://github.com/xaviergonz/mobx-keystone/tree/master/packages/mobx-keystone-yjs) | [demo](https://mobx-keystone.js.org/examples/yjs-binding) |
+| [PSPDFKit](https://www.nutrient.io/) |  | [yjs-pspdfkit](https://github.com/hoangqwe159/yjs-pspdfkit) | [demo](https://github.com/hoangqwe159/yjs-pspdfkit) |
+| [Rows n'Columns](https://www.rowsncolumns.app/) | ✔ | [@rowsncolumns/y-spreadsheet](https://docs.rowsncolumns.app/collaboration/yjs-collaboration) | |

 ### Providers

@ -100,26 +173,56 @@ and storing shared data for offline usage is quite a hassle. **Providers**
 manage all that for you and are the perfect starting point for your
 collaborative app.

+> This list of providers is incomplete. Please open PRs to add your providers to
+> this list!
+
+#### Connection Providers
+
 <dl>
+  <dt><a href="https://github.com/yjs/y-websocket">y-websocket</a></dt>
+  <dd>
+A module that contains a simple websocket backend and a websocket client that
+connects to that backend. <a href="https://github.com/yjs/y-redis/"><b>y-redis</b></a>,
+<b>y-sweet</b>, <b>ypy-websocket</b> and <a href="https://tiptap.dev/docs/hocuspocus/introduction">
+<b>Hocuspocus</b></a> (see below) are alternative
+backends to y-websocket.
+  </dd>
  <dt><a href="https://github.com/yjs/y-webrtc">y-webrtc</a></dt>
  <dd>
 Propagates document updates peer-to-peer using WebRTC. The peers exchange
-signaling data over signaling servers. Publically available signaling servers
+signaling data over signaling servers. Publicly available signaling servers
 are available. Communication over the signaling servers can be encrypted by
 providing a shared secret, keeping the connection information and the shared
 document private.
  </dd>
-  <dt><a href="https://github.com/yjs/y-websocket">y-websocket</a></dt>
+  <dt><a href="https://github.com/liveblocks/liveblocks">@liveblocks/yjs </a> 🌟</dt>
  <dd>
-A module that contains a simple websocket backend and a websocket client that
-connects to that backend. The backend can be extended to persist updates in a
-leveldb database.
+<a href="https://liveblocks.io/document/yjs">Liveblocks Yjs</a> provides a fully
+hosted WebSocket infrastructure and persisted data store for Yjs
+documents. No configuration or maintenance is required. It also features
+Yjs webhook events, REST API to read and update Yjs documents, and a
+browser DevTools extension.
  </dd>
-  <dt><a href="https://github.com/yjs/y-indexeddb">y-indexeddb</a></dt>
+  <dt><a href="https://github.com/drifting-in-space/y-sweet">y-sweet</a> ⭐</dt>
  <dd>
-Efficiently persists document updates to the browsers indexeddb database.
-The document is immediately available and only diffs need to be synced through the
-network provider.
+A standalone yjs server with persistence to S3 or filesystem. They offer a
+<a href="https://y-sweet.cloud">cloud service</a> as well.
+  </dd>
+  <dt><a href="https://github.com/ueberdosis/hocuspocus">Hocuspocus</a> ⭐</dt>
+  <dd>
+A standalone extensible yjs server with sqlite persistence, webhooks, auth and more.
+  </dd>
+  <dt><a href="https://docs.superviz.com/collaboration/integrations/YJS/overview">@superviz/yjs</a></dt>
+  <dd>
+    SuperViz Yjs Provider comes with a secure, scalable real-time infrastructure
+    for Yjs documents, fully compatible with a set of real-time
+    collaboration components offered by SuperViz. This solution ensures
+    synchronization, offline editing, and real-time updates, enabling
+    multiple users to collaborate effectively within shared workspaces.
+  </dd>
+  <dt><a href="https://docs.partykit.io/reference/y-partykit-api/">PartyKit</a></dt>
+  <dd>
+Cloud service for building multiplayer apps.
  </dd>
  <dt><a href="https://github.com/marcopolo/y-libp2p">y-libp2p</a></dt>
  <dd>
@ -142,14 +245,90 @@ Use Matrix as transport and storage of Yjs updates, so you can focus building
 your client app and Matrix can provide powerful features like Authentication,
 Authorization, Federation, hosting (self-hosting or SaaS) and even End-to-End
 Encryption (E2EE).
-</dd>
+  </dd>
+  <dt><a href="https://github.com/y-crdt/yrb-actioncable">yrb-actioncable</a></dt>
+  <dd>
+An ActionCable companion for Yjs clients. There is a fitting
+<a href="https://github.com/y-crdt/yrb-redis">redis extension</a> as well.
+  </dd>
+  <dt><a href="https://github.com/y-crdt/ypy-websocket">ypy-websocket</a></dt>
+  <dd>
+Websocket backend, written in Python.
+  </dd>
+  <dt><a href="https://tinybase.org/">Tinybase</a></dt>
+  <dd>
+The reactive data store for local-first apps. They support multiple CRDTs and
+    different network technologies.
+  </dd>
+  <dt><a href="https://codeberg.org/webxdc/y-webxdc">y-webxdc</a></dt>
+  <dd>
+Provider for sharing data in <a href="https://webxdc.org">webxdc chat apps</a>.
+  </dd>
+  <dt><a href="https://www.secsync.com/">secsync</a></dt>
+  <dd>
+An architecture to relay end-to-end encrypted CRDTs over a central service.
+  </dd>
+
+</dl>
+
+#### Persistence Providers
+
+<dl>
+  <dt><a href="https://github.com/yjs/y-indexeddb">y-indexeddb</a></dt>
+  <dd>
+Efficiently persists document updates to the browsers indexeddb database.
+The document is immediately available and only diffs need to be synced through the
+network provider.
+  </dd>
  <dt><a href="https://github.com/MaxNoetzold/y-mongodb-provider">y-mongodb-provider</a></dt>
  <dd>
 Adds persistent storage to a server with MongoDB. Can be used with the
 y-websocket provider.
-</dd>
+  </dd>
+  <dt><a href="https://github.com/podraven/y-fire">y-fire</a></dt>
+  <dd>
+A database and connection provider for Yjs based on Firestore.
+  </dd>
+  <dt><a href="https://github.com/malte-j/y-op-sqlite">y-op-sqlite</a></dt>
+  <dd>
+  Persist YJS updates in your React Native app using
+   <a href="https://github.com/OP-Engineering/op-sqlite">op-sqlite</a>
+  , the fastest SQLite library for React Native.  
+  </dd>
+  <dt><a href="https://github.com/MaxNoetzold/y-postgresql">y-postgresql</a></dt>
+  <dd>
+  Provides persistent storage for a web server using PostgreSQL and
+  is easily compatible with y-websocket.  
+  </dd>
+  <dt><a href="https://github.com/kapv89/k_yrs_go">k_yrs_go</a></dt>
+  <dd>
+  Golang database server for YJS CRDT using Postgres + Redis
+  </dd>
 </dl>

+### Tooling
+
+* [y-sweet debugger](https://docs.jamsocket.com/y-sweet/advanced/debugger)
+* [liveblocks devtools](https://liveblocks.io/devtools)
+* [Yjs inspector](https://inspector.yjs.dev)
+
+### Ports
+
+There are several Yjs-compatible ports to other programming languages.
+
+* [y-octo](https://github.com/toeverything/y-octo) - Rust implementation by
+[AFFiNE](https://affine.pro)
+* [y-crdt](https://github.com/y-crdt/y-crdt) - Rust implementation with multiple
+language bindings to other languages
+  * [yrs](https://github.com/y-crdt/y-crdt/tree/main/yrs) - Rust interface
+  * [ypy](https://github.com/y-crdt/ypy) - Python binding
+  * [yrb](https://github.com/y-crdt/yrb) - Ruby binding
+  * [yswift](https://github.com/y-crdt/yswift) - Swift binding
+  * [yffi](https://github.com/y-crdt/y-crdt/tree/main/yffi) - C-FFI
+  * [ywasm](https://github.com/y-crdt/y-crdt/tree/main/ywasm) - WASM binding
+  * [y_ex](https://github.com/satoren/y_ex) - Elixir bindings
+* [ycs](https://github.com/yjs/ycs) - .Net compatible C# implementation.
+
 ## Getting Started

 Install Yjs and a provider with your favorite package manager:
@ -161,12 +340,15 @@ npm i yjs y-websocket
 Start the y-websocket server:

 ```sh
-PORT=1234 node ./node_modules/y-websocket/bin/server.js
+PORT=1234 node ./node_modules/y-websocket/bin/server.cjs
 ```

 ### Example: Observe types

 ```js
+import * as Y from 'yjs';
+
+const doc = new Y.Doc();
 const yarray = doc.getArray('my-array')
 yarray.observe(event => {
  console.log('yarray was modified')
@ -259,6 +441,11 @@ necessary.
  </p>
  <pre>const yarray = new Y.Array()</pre>
  <dl>
+    <b><code>
+Y.Array.from(Array&lt;object|boolean|Array|string|number|null|Uint8Array|Y.Type&gt;):
+Y.Array
+    </code></b>
+    <dd>An alternative factory function to create a Y.Array based on existing content.</dd>
    <b><code>parent:Y.AbstractType|null</code></b>
    <dd></dd>
    <b><code>insert(index:number, content:Array&lt;object|boolean|Array|string|number|null|Uint8Array|Y.Type&gt;)</code></b>
@ -288,6 +475,11 @@ forEach(function(value:object|boolean|Array|string|number|null|Uint8Array|Y.Type
    <dd></dd>
    <b><code>map(function(T, number, YArray):M):Array&lt;M&gt;</code></b>
    <dd></dd>
+    <b><code>clone(): Y.Array</code></b>
+    <dd>
+Clone all values into a fresh Y.Array instance. The returned type can be
+included into the Yjs document.
+    </dd>
    <b><code>toArray():Array&lt;object|boolean|Array|string|number|null|Uint8Array|Y.Type&gt;</code></b>
    <dd>Copies the content of this YArray to a new Array.</dd>
    <b><code>toJSON():Array&lt;Object|boolean|Array|string|number|null&gt;</code></b>
@ -344,8 +536,6 @@ or any of its children.
    <dd></dd>
    <b><code>has(key:string):boolean</code></b>
    <dd></dd>
-    <b><code>get(index:number)</code></b>
-    <dd></dd>
    <b><code>clear()</code></b>
    <dd>Removes all elements from this YMap.</dd>
    <b><code>clone():Y.Map</code></b>
@ -642,6 +832,8 @@ type. Doesn't log types that have not been defined (using
  <dd>Define a shared Y.Map type. Is equivalent to <code>y.get(string, Y.Map)</code>.</dd>
  <b><code>getText(string):Y.Text</code></b>
  <dd>Define a shared Y.Text type. Is equivalent to <code>y.get(string, Y.Text)</code>.</dd>
+  <b><code>getXmlElement(string, string):Y.XmlElement</code></b>
+  <dd>Define a shared Y.XmlElement type. Is equivalent to <code>y.get(string, Y.XmlElement)</code>.</dd>
  <b><code>getXmlFragment(string):Y.XmlFragment</code></b>
  <dd>Define a shared Y.XmlFragment type. Is equivalent to <code>y.get(string, Y.XmlFragment)</code>.</dd>
  <b><code>on(string, function)</code></b>
@ -656,7 +848,8 @@ type. Doesn't log types that have not been defined (using
  <b><code>on('update', function(updateMessage:Uint8Array, origin:any, Y.Doc):void)</code></b>
  <dd>
 Listen to document updates. Document updates must be transmitted to all other
-peers. You can apply document updates in any order and multiple times.
+peers. You can apply document updates in any order and multiple times. Use `updateV2`
+to receive V2 events.
  </dd>
  <b><code>on('beforeTransaction', function(Y.Transaction, Y.Doc):void)</code></b>
  <dd>Emitted before each transaction.</dd>
@ -696,7 +889,7 @@ doc1.getArray('myarray').insert(0, ['Hello doc2, you got this?'])
 doc2.getArray('myarray').get(0) // => 'Hello doc2, you got this?'
 ```

-Yjs internally maintains a [state vector](#State-Vector) that denotes the next
+Yjs internally maintains a [state vector](#state-vector) that denotes the next
 expected clock from each client. In a different interpretation it holds the
 number of structs created by each client. When two clients sync, you can either
 exchange the complete document structure or only the differences by sending the
@ -748,17 +941,43 @@ const diff2 = Y.diffUpdate(currentState2, stateVector1)

 // sync clients
 currentState1 = Y.mergeUpdates([currentState1, diff2])
-currentState1 = Y.mergeUpdates([currentState1, diff1])
+currentState2 = Y.mergeUpdates([currentState2, diff1])
+```
+
+#### Obfuscating Updates
+
+If one of your users runs into a weird bug (e.g. the rich-text editor throws
+error messages), then you don't have to request the full document from your
+user. Instead, they can obfuscate the document (i.e. replace the content with
+meaningless generated content) before sending it to you. Note that someone might
+still deduce the type of content by looking at the general structure of the
+document. But this is much better than requesting the original document.
+
+Obfuscated updates contain all the CRDT-related data that is required for
+merging. So it is safe to merge obfuscated updates.
+
+```javascript
+const ydoc = new Y.Doc()
+// perform some changes..
+ydoc.getText().insert(0, 'hello world')
+const update = Y.encodeStateAsUpdate(ydoc)
+// the below update contains scrambled data
+const obfuscatedUpdate = Y.obfuscateUpdate(update)
+const ydoc2 = new Y.Doc()
+Y.applyUpdate(ydoc2, obfuscatedUpdate)
+ydoc2.getText().toString() // => "00000000000"
 ```

 #### Using V2 update format

 Yjs implements two update formats. By default you are using the V1 update format.
-You can opt-in into the V2 update format wich provides much better compression.
+You can opt-in into the V2 update format which provides much better compression.
 It is not yet used by all providers. However, you can already use it if
 you are building your own provider. All below functions are available with the
-suffix "V2". E.g. `Y.applyUpdate` ⇒ `Y.applyUpdateV2`. We also support conversion
-functions between both formats: `Y.convertUpdateFormatV1ToV2` & `Y.convertUpdateFormatV2ToV1`.
+suffix "V2". E.g. `Y.applyUpdate` ⇒ `Y.applyUpdateV2`. Also when listening to updates
+you need to specifically need listen for V2 events e.g. `yDoc.on('updateV2', …)`.
+We also support conversion functions between both formats:
+`Y.convertUpdateFormatV1ToV2` & `Y.convertUpdateFormatV2ToV1`.

 #### Update API

@ -883,7 +1102,7 @@ encoding format for document updates. If you prefer JSON encoding, you can
 simply JSON.stringify / JSON.parse the relative position instead.
  </dd>
  <b><code>Y.decodeRelativePosition(Uint8Array):RelativePosition</code></b>
-  <dd>Decode a binary-encoded relative position to a RelativePositon object.</dd>
+  <dd>Decode a binary-encoded relative position to a RelativePosition object.</dd>
 </dl>

 ### Y.UndoManager
@ -1003,7 +1222,7 @@ doc.transact(() => {
  ytext.insert(0, 'abc')
 }, 41)
 undoManager.undo()
-ytext.toString() // => '' (not tracked because 41 is not an instance of
+ytext.toString() // => 'abc' (not tracked because 41 is not an instance of
                 //        `trackedTransactionorigins`)
 ytext.delete(0, 3) // revert change

@ -1063,11 +1282,11 @@ More information about the specific implementation is available in

 CRDTs that are suitable for shared text editing suffer from the fact that they
 only grow in size. There are CRDTs that do not grow in size, but they do not
-have the characteristics that are benificial for shared text editing (like
+have the characteristics that are beneficial for shared text editing (like
 intention preservation). Yjs implements many improvements to the original
 algorithm that diminish the trade-off that the document only grows in size. We
 can't garbage collect deleted structs (tombstones) while ensuring a unique
-order of the structs. But we can 1. merge preceeding structs into a single
+order of the structs. But we can 1. merge preceding structs into a single
 struct to reduce the amount of meta information, 2. we can delete content from
 the struct if it is deleted, and 3. we can garbage collect tombstones if we
 don't care about the order of the structs anymore (e.g. if the parent was
--- a/funding.json
+++ b/funding.json
@ -0,0 +1,142 @@
+{
+  "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
+  }
+}
--- a/package-lock.json
+++ b/package-lock.json
--- a/package.json
+++ b/package.json
@ -1,6 +1,6 @@
 {
  "name": "yjs",
-  "version": "13.5.44",
+  "version": "13.6.24",
  "description": "Shared Editing Library",
  "main": "./dist/yjs.cjs",
  "module": "./dist/yjs.mjs",
@ -12,9 +12,10 @@
    "url": "https://github.com/sponsors/dmonad"
  },
  "scripts": {
-    "test": "npm run dist && node ./dist/tests.cjs --repetition-time 50",
+    "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": "rm -rf dist && rollup -c && tsc",
+    "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",
@ -75,19 +76,24 @@
  },
  "homepage": "https://docs.yjs.dev",
  "dependencies": {
-    "lib0": "^0.2.49"
+    "lib0": "^0.2.99"
  },
  "devDependencies": {
-    "@rollup/plugin-commonjs": "^17.0.0",
-    "@rollup/plugin-node-resolve": "^11.2.1",
+    "@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": "^0.23.2",
-    "rollup": "^2.60.0",
+    "markdownlint-cli": "^0.41.0",
+    "rollup": "^3.20.0",
    "standard": "^16.0.4",
    "tui-jsdoc-template": "^1.2.2",
-    "typescript": "^4.4.4",
+    "typescript": "^4.9.5",
    "y-protocols": "^1.0.5"
+  },
+  "engines": {
+    "npm": ">=8.0.0",
+    "node": ">=16.0.0"
  }
 }
--- a/rollup.config.js
+++ b/rollup.config.js
@ -42,13 +42,7 @@ export default [{
    name: 'Y',
    file: 'dist/yjs.cjs',
    format: 'cjs',
-    sourcemap: true,
-    paths: path => {
-      if (/^lib0\//.test(path)) {
-        return `lib0/dist/${path.slice(5)}.cjs`
-      }
-      return path
-    }
+    sourcemap: true
  },
  external: id => /^lib0\//.test(id)
 }, {
@ -88,7 +82,7 @@ export default [{
  plugins: [
    debugResolve,
    nodeResolve({
-      mainFields: ['module', 'browser', 'main']
+      mainFields: ['browser', 'module', 'main']
    }),
    commonjs()
  ]
@ -103,9 +97,10 @@ export default [{
  plugins: [
    debugResolve,
    nodeResolve({
-      mainFields: ['module', 'main']
+      mainFields: ['node', 'module', 'main'],
+      exportConditions: ['node', 'module', 'import', 'default']
    }),
    commonjs()
  ],
-  external: ['isomorphic.js']
+  external: id => /^lib0\//.test(id)
 }]
--- a/src/index.js
+++ b/src/index.js
@ -18,8 +18,10 @@ export {
  Item,
  AbstractStruct,
  GC,
+  Skip,
  ContentBinary,
  ContentDeleted,
+  ContentDoc,
  ContentEmbed,
  ContentFormat,
  ContentJSON,
@ -48,8 +50,11 @@ export {
  findRootTypeKey,
  findIndexSS,
  getItem,
+  getItemCleanStart,
+  getItemCleanEnd,
  typeListToArraySnapshot,
  typeMapGetSnapshot,
+  typeMapGetAllSnapshot,
  createDocFromSnapshot,
  iterateDeletedStructs,
  applyUpdate,
@ -90,7 +95,15 @@ export {
  diffUpdateV2,
  convertUpdateFormatV1ToV2,
  convertUpdateFormatV2ToV1,
-  UpdateEncoderV1
+  obfuscateUpdate,
+  obfuscateUpdateV2,
+  UpdateEncoderV1,
+  UpdateEncoderV2,
+  UpdateDecoderV1,
+  UpdateDecoderV2,
+  equalDeleteSets,
+  mergeDeleteSets,
+  snapshotContainsUpdate
 } from './internals.js'

 const glo = /** @type {any} */ (typeof globalThis !== 'undefined'
--- a/src/internals.js
+++ b/src/internals.js
@ -1,4 +1,3 @@
-
 export * from './utils/AbstractConnector.js'
 export * from './utils/DeleteSet.js'
 export * from './utils/Doc.js'
--- a/src/structs/AbstractStruct.js
+++ b/src/structs/AbstractStruct.js
@ -1,4 +1,3 @@
-
 import {
  UpdateEncoderV1, UpdateEncoderV2, ID, Transaction // eslint-disable-line
 } from '../internals.js'
@ -27,7 +26,7 @@ export class AbstractStruct {
   * This method is already assuming that `this.id.clock + this.length === this.id.clock`.
   * Also this method does *not* remove right from StructStore!
   * @param {AbstractStruct} right
-   * @return {boolean} wether this merged with right
+   * @return {boolean} whether this merged with right
   */
  mergeWith (right) {
    return false
--- a/src/structs/ContentAny.js
+++ b/src/structs/ContentAny.js
@ -2,6 +2,11 @@ import {
  UpdateEncoderV1, UpdateEncoderV2, UpdateDecoderV1, UpdateDecoderV2, Transaction, Item, StructStore // eslint-disable-line
 } from '../internals.js'

+import * as env from 'lib0/environment'
+import * as object from 'lib0/object'
+
+const isDevMode = env.getVariable('node_env') === 'development'
+
 export class ContentAny {
  /**
   * @param {Array<any>} arr
@ -11,6 +16,7 @@ export class ContentAny {
     * @type {Array<any>}
     */
    this.arr = arr
+    isDevMode && object.deepFreeze(arr)
  }

  /**
--- a/src/structs/ContentDeleted.js
+++ b/src/structs/ContentDeleted.js
@ -1,4 +1,3 @@
-
 import {
  addToDeleteSet,
  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, StructStore, Item, Transaction // eslint-disable-line
--- a/src/structs/ContentDoc.js
+++ b/src/structs/ContentDoc.js
@ -1,4 +1,3 @@
-
 import {
  Doc, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, StructStore, Transaction, Item // eslint-disable-line
 } from '../internals.js'
--- a/src/structs/ContentEmbed.js
+++ b/src/structs/ContentEmbed.js
@ -1,4 +1,3 @@
-
 import {
  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, StructStore, Item, Transaction // eslint-disable-line
 } from '../internals.js'
--- a/src/structs/ContentFormat.js
+++ b/src/structs/ContentFormat.js
@ -1,6 +1,5 @@
-
 import {
-  AbstractType, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Item, StructStore, Transaction // eslint-disable-line
+  YText, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Item, StructStore, Transaction // eslint-disable-line
 } from '../internals.js'

 import * as error from 'lib0/error'
@ -47,28 +46,30 @@ export class ContentFormat {
  }

  /**
-   * @param {number} offset
+   * @param {number} _offset
   * @return {ContentFormat}
   */
-  splice (offset) {
+  splice (_offset) {
    throw error.methodUnimplemented()
  }

  /**
-   * @param {ContentFormat} right
+   * @param {ContentFormat} _right
   * @return {boolean}
   */
-  mergeWith (right) {
+  mergeWith (_right) {
    return false
  }

  /**
-   * @param {Transaction} transaction
+   * @param {Transaction} _transaction
   * @param {Item} item
   */
-  integrate (transaction, item) {
+  integrate (_transaction, item) {
    // @todo searchmarker are currently unsupported for rich text documents
-    /** @type {AbstractType<any>} */ (item.parent)._searchMarker = null
+    const p = /** @type {YText} */ (item.parent)
+    p._searchMarker = null
+    p._hasFormatting = true
  }

  /**
--- a/src/structs/ContentType.js
+++ b/src/structs/ContentType.js
@ -1,4 +1,3 @@
-
 import {
  readYArray,
  readYMap,
@ -108,7 +107,7 @@ export class ContentType {
    while (item !== null) {
      if (!item.deleted) {
        item.delete(transaction)
-      } else {
+      } else if (item.id.clock < (transaction.beforeState.get(item.id.client) || 0)) {
        // This will be gc'd later and we want to merge it if possible
        // We try to merge all deleted items after each transaction,
        // but we have no knowledge about that this needs to be merged
@ -120,7 +119,7 @@ export class ContentType {
    this.type._map.forEach(item => {
      if (!item.deleted) {
        item.delete(transaction)
-      } else {
+      } else if (item.id.clock < (transaction.beforeState.get(item.id.client) || 0)) {
        // same as above
        transaction._mergeStructs.push(item)
      }
--- a/src/structs/GC.js
+++ b/src/structs/GC.js
@ -1,4 +1,3 @@
-
 import {
  AbstractStruct,
  addStruct,
--- a/src/structs/Item.js
+++ b/src/structs/Item.js
@ -1,4 +1,3 @@
-
 import {
  GC,
  getState,
@ -23,11 +22,12 @@ import {
  readContentType,
  addChangedTypeToTransaction,
  isDeleted,
-  DeleteSet, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, ContentType, ContentDeleted, StructStore, ID, AbstractType, Transaction // eslint-disable-line
+  StackItem, DeleteSet, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, ContentType, ContentDeleted, StructStore, ID, AbstractType, Transaction // eslint-disable-line
 } from '../internals.js'

 import * as error from 'lib0/error'
 import * as binary from 'lib0/binary'
+import * as array from 'lib0/array'

 /**
 * @todo This should return several items
@ -120,6 +120,12 @@ export const splitItem = (transaction, leftItem, diff) => {
  return rightItem
 }

+/**
+ * @param {Array<StackItem>} stack
+ * @param {ID} id
+ */
+const isDeletedByUndoStack = (stack, id) => array.some(stack, /** @param {StackItem} s */ s => isDeleted(s.deletions, id))
+
 /**
 * Redoes the effect of this operation.
 *
@ -128,12 +134,13 @@ export const splitItem = (transaction, leftItem, diff) => {
 * @param {Set<Item>} redoitems
 * @param {DeleteSet} itemsToDelete
 * @param {boolean} ignoreRemoteMapChanges
+ * @param {import('../utils/UndoManager.js').UndoManager} um
 *
 * @return {Item|null}
 *
 * @private
 */
-export const redoItem = (transaction, item, redoitems, itemsToDelete, ignoreRemoteMapChanges) => {
+export const redoItem = (transaction, item, redoitems, itemsToDelete, ignoreRemoteMapChanges, um) => {
  const doc = transaction.doc
  const store = doc.store
  const ownClientID = doc.clientID
@ -153,7 +160,7 @@ export const redoItem = (transaction, item, redoitems, itemsToDelete, ignoreRemo
  // make sure that parent is redone
  if (parentItem !== null && parentItem.deleted === true) {
    // try to undo parent if it will be undone anyway
-    if (parentItem.redone === null && (!redoitems.has(parentItem) || redoItem(transaction, parentItem, redoitems, itemsToDelete, ignoreRemoteMapChanges) === null)) {
+    if (parentItem.redone === null && (!redoitems.has(parentItem) || redoItem(transaction, parentItem, redoitems, itemsToDelete, ignoreRemoteMapChanges, um) === null)) {
      return null
    }
    while (parentItem.redone !== null) {
@ -203,13 +210,10 @@ export const redoItem = (transaction, item, redoitems, itemsToDelete, ignoreRemo
      left = item
      // Iterate right while right is in itemsToDelete
      // If it is intended to delete right while item is redone, we can expect that item should replace right.
-      while (left !== null && left.right !== null && isDeleted(itemsToDelete, left.right.id)) {
+      while (left !== null && left.right !== null && (left.right.redone || isDeleted(itemsToDelete, left.right.id) || isDeletedByUndoStack(um.undoStack, left.right.id) || isDeletedByUndoStack(um.redoStack, left.right.id))) {
        left = left.right
-      }
-      // follow redone
-      // trace redone until parent matches
-      while (left !== null && left.redone !== null) {
-        left = getItemCleanStart(transaction, left.redone)
+        // follow redone
+        while (left.redone) left = getItemCleanStart(transaction, left.redone)
      }
      if (left && left.right !== null) {
        // It is not possible to redo this item because it conflicts with a
@ -384,14 +388,12 @@ export class Item extends AbstractStruct {
    }
    if ((this.left && this.left.constructor === GC) || (this.right && this.right.constructor === GC)) {
      this.parent = null
-    }
-    // only set parent if this shouldn't be garbage collected
-    if (!this.parent) {
+    } else if (!this.parent) {
+      // only set parent if this shouldn't be garbage collected
      if (this.left && this.left.constructor === Item) {
        this.parent = this.left.parent
        this.parentSub = this.left.parentSub
-      }
-      if (this.right && this.right.constructor === Item) {
+      } else if (this.right && this.right.constructor === Item) {
        this.parent = this.right.parent
        this.parentSub = this.right.parentSub
      }
@ -756,48 +758,48 @@ export class AbstractContent {
  }

  /**
-   * @param {number} offset
+   * @param {number} _offset
   * @return {AbstractContent}
   */
-  splice (offset) {
+  splice (_offset) {
    throw error.methodUnimplemented()
  }

  /**
-   * @param {AbstractContent} right
+   * @param {AbstractContent} _right
   * @return {boolean}
   */
-  mergeWith (right) {
+  mergeWith (_right) {
    throw error.methodUnimplemented()
  }

  /**
-   * @param {Transaction} transaction
-   * @param {Item} item
+   * @param {Transaction} _transaction
+   * @param {Item} _item
   */
-  integrate (transaction, item) {
+  integrate (_transaction, _item) {
    throw error.methodUnimplemented()
  }

  /**
-   * @param {Transaction} transaction
+   * @param {Transaction} _transaction
   */
-  delete (transaction) {
+  delete (_transaction) {
    throw error.methodUnimplemented()
  }

  /**
-   * @param {StructStore} store
+   * @param {StructStore} _store
   */
-  gc (store) {
+  gc (_store) {
    throw error.methodUnimplemented()
  }

  /**
-   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
-   * @param {number} offset
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} _encoder
+   * @param {number} _offset
   */
-  write (encoder, offset) {
+  write (_encoder, _offset) {
    throw error.methodUnimplemented()
  }

--- a/src/structs/Skip.js
+++ b/src/structs/Skip.js
@ -1,4 +1,3 @@
-
 import {
  AbstractStruct,
  UpdateEncoderV1, UpdateEncoderV2, StructStore, Transaction, ID // eslint-disable-line
--- a/src/types/AbstractType.js
+++ b/src/types/AbstractType.js
@ -1,4 +1,3 @@
-
 import {
  removeEventHandlerListener,
  callEventHandlerListeners,
@ -18,6 +17,12 @@ import * as map from 'lib0/map'
 import * as iterator from 'lib0/iterator'
 import * as error from 'lib0/error'
 import * as math from 'lib0/math'
+import * as log from 'lib0/logging'
+
+/**
+ * https://docs.yjs.dev/getting-started/working-with-shared-types#caveats
+ */
+export const warnPrematureAccess = () => { log.warn('Invalid access: Add Yjs type to a document before reading data.') }

 const maxSearchMarker = 80

@ -150,11 +155,11 @@ export const findMarker = (yarray, index) => {
  //   }
  // }
  // if (marker) {
-  //   if (window.lengthes == null) {
-  //     window.lengthes = []
-  //     window.getLengthes = () => window.lengthes.sort((a, b) => a - b)
+  //   if (window.lengths == null) {
+  //     window.lengths = []
+  //     window.getLengths = () => window.lengths.sort((a, b) => a - b)
  //   }
-  //   window.lengthes.push(marker.index - pindex)
+  //   window.lengths.push(marker.index - pindex)
  //   console.log('distance', marker.index - pindex, 'len', p && p.parent.length)
  // }
  if (marker !== null && math.abs(marker.index - pindex) < /** @type {YText|YArray<any>} */ (p.parent).length / maxSearchMarker) {
@ -216,6 +221,7 @@ export const updateMarkerChanges = (searchMarker, index, len) => {
 * @return {Array<Item>}
 */
 export const getTypeChildren = t => {
+  t.doc ?? warnPrematureAccess()
  let s = t._start
  const arr = []
  while (s) {
@ -317,6 +323,10 @@ export class AbstractType {
  }

  /**
+   * Makes a copy of this data type that can be included somewhere else.
+   *
+   * Note that the content is only readable _after_ it has been included somewhere in the Ydoc.
+   *
   * @return {AbstractType<EventType>}
   */
  clone () {
@ -324,9 +334,9 @@ export class AbstractType {
  }

  /**
-   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} _encoder
   */
-  _write (encoder) { }
+  _write (_encoder) { }

  /**
   * The first non-deleted item
@ -344,9 +354,9 @@ export class AbstractType {
   * Must be implemented by each type.
   *
   * @param {Transaction} transaction
-   * @param {Set<null|string>} parentSubs Keys changed on this type. `null` if list was modified.
+   * @param {Set<null|string>} _parentSubs Keys changed on this type. `null` if list was modified.
   */
-  _callObserver (transaction, parentSubs) {
+  _callObserver (transaction, _parentSubs) {
    if (!transaction.local && this._searchMarker) {
      this._searchMarker.length = 0
    }
@ -405,6 +415,7 @@ export class AbstractType {
 * @function
 */
 export const typeListSlice = (type, start, end) => {
+  type.doc ?? warnPrematureAccess()
  if (start < 0) {
    start = type._length + start
  }
@ -440,6 +451,7 @@ export const typeListSlice = (type, start, end) => {
 * @function
 */
 export const typeListToArray = type => {
+  type.doc ?? warnPrematureAccess()
  const cs = []
  let n = type._start
  while (n !== null) {
@ -478,7 +490,7 @@ export const typeListToArraySnapshot = (type, snapshot) => {
 }

 /**
- * Executes a provided function on once on overy element of this YArray.
+ * Executes a provided function on once on every element of this YArray.
 *
 * @param {AbstractType<any>} type
 * @param {function(any,number,any):void} f A function to execute on every element of this YArray.
@ -489,6 +501,7 @@ export const typeListToArraySnapshot = (type, snapshot) => {
 export const typeListForEach = (type, f) => {
  let index = 0
  let n = type._start
+  type.doc ?? warnPrematureAccess()
  while (n !== null) {
    if (n.countable && !n.deleted) {
      const c = n.content.getContent()
@ -570,7 +583,7 @@ export const typeListCreateIterator = type => {
 }

 /**
- * Executes a provided function on once on overy element of this YArray.
+ * Executes a provided function on once on every element of this YArray.
 * Operates on a snapshotted state of the document.
 *
 * @param {AbstractType<any>} type
@ -603,6 +616,7 @@ export const typeListForEachSnapshot = (type, f, snapshot) => {
 * @function
 */
 export const typeListGet = (type, index) => {
+  type.doc ?? warnPrematureAccess()
  const marker = findMarker(type, index)
  let n = type._start
  if (marker !== null) {
@ -683,7 +697,7 @@ export const typeListInsertGenericsAfter = (transaction, parent, referenceItem,
  packJsonContent()
 }

-const lengthExceeded = error.create('Length exceeded!')
+const lengthExceeded = () => error.create('Length exceeded!')

 /**
 * @param {Transaction} transaction
@ -696,7 +710,7 @@ const lengthExceeded = error.create('Length exceeded!')
 */
 export const typeListInsertGenerics = (transaction, parent, index, content) => {
  if (index > parent._length) {
-    throw lengthExceeded
+    throw lengthExceeded()
  }
  if (index === 0) {
    if (parent._searchMarker) {
@ -737,7 +751,7 @@ export const typeListInsertGenerics = (transaction, parent, index, content) => {

 /**
 * Pushing content is special as we generally want to push after the last item. So we don't have to update
- * the serach marker.
+ * the search marker.
 *
 * @param {Transaction} transaction
 * @param {AbstractType<any>} parent
@ -798,7 +812,7 @@ export const typeListDelete = (transaction, parent, index, length) => {
    n = n.right
  }
  if (length > 0) {
-    throw lengthExceeded
+    throw lengthExceeded()
  }
  if (parent._searchMarker) {
    updateMarkerChanges(parent._searchMarker, startIndex, -startLength + length /* in case we remove the above exception */)
@ -871,6 +885,7 @@ export const typeMapSet = (transaction, parent, key, value) => {
 * @function
 */
 export const typeMapGet = (parent, key) => {
+  parent.doc ?? warnPrematureAccess()
  const val = parent._map.get(key)
  return val !== undefined && !val.deleted ? val.content.getContent()[val.length - 1] : undefined
 }
@ -887,6 +902,7 @@ export const typeMapGetAll = (parent) => {
   * @type {Object<string,any>}
   */
  const res = {}
+  parent.doc ?? warnPrematureAccess()
  parent._map.forEach((value, key) => {
    if (!value.deleted) {
      res[key] = value.content.getContent()[value.length - 1]
@ -904,6 +920,7 @@ export const typeMapGetAll = (parent) => {
 * @function
 */
 export const typeMapHas = (parent, key) => {
+  parent.doc ?? warnPrematureAccess()
  const val = parent._map.get(key)
  return val !== undefined && !val.deleted
 }
@ -926,10 +943,41 @@ export const typeMapGetSnapshot = (parent, key, snapshot) => {
 }

 /**
- * @param {Map<string,Item>} map
+ * @param {AbstractType<any>} parent
+ * @param {Snapshot} snapshot
+ * @return {Object<string,Object<string,any>|number|null|Array<any>|string|Uint8Array|AbstractType<any>|undefined>}
+ *
+ * @private
+ * @function
+ */
+export const typeMapGetAllSnapshot = (parent, snapshot) => {
+  /**
+   * @type {Object<string,any>}
+   */
+  const res = {}
+  parent._map.forEach((value, key) => {
+    /**
+     * @type {Item|null}
+     */
+    let v = value
+    while (v !== null && (!snapshot.sv.has(v.id.client) || v.id.clock >= (snapshot.sv.get(v.id.client) || 0))) {
+      v = v.left
+    }
+    if (v !== null && isVisible(v, snapshot)) {
+      res[key] = v.content.getContent()[v.length - 1]
+    }
+  })
+  return res
+}
+
+/**
+ * @param {AbstractType<any> & { _map: Map<string, Item> }} type
 * @return {IterableIterator<Array<any>>}
 *
 * @private
 * @function
 */
-export const createMapIterator = map => iterator.iteratorFilter(map.entries(), /** @param {any} entry */ entry => !entry[1].deleted)
+export const createMapIterator = type => {
+  type.doc ?? warnPrematureAccess()
+  return iterator.iteratorFilter(type._map.entries(), /** @param {any} entry */ entry => !entry[1].deleted)
+}
--- a/src/types/YArray.js
+++ b/src/types/YArray.js
@ -16,6 +16,7 @@ import {
  YArrayRefID,
  callTypeObservers,
  transact,
+  warnPrematureAccess,
  ArraySearchMarker, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Doc, Transaction, Item // eslint-disable-line
 } from '../internals.js'
 import { typeListSlice } from './AbstractType.js'
@ -25,16 +26,7 @@ import { typeListSlice } from './AbstractType.js'
 * @template T
 * @extends YEvent<YArray<T>>
 */
-export class YArrayEvent extends YEvent {
-  /**
-   * @param {YArray<T>} yarray The changed type
-   * @param {Transaction} transaction The transaction object
-   */
-  constructor (yarray, transaction) {
-    super(yarray, transaction)
-    this._transaction = transaction
-  }
-}
+export class YArrayEvent extends YEvent {}

 /**
 * A shared Array implementation.
@ -58,11 +50,14 @@ export class YArray extends AbstractType {

  /**
   * Construct a new YArray containing the specified items.
-   * @template T
+   * @template {Object<string,any>|Array<any>|number|null|string|Uint8Array} T
   * @param {Array<T>} items
   * @return {YArray<T>}
   */
  static from (items) {
+    /**
+     * @type {YArray<T>}
+     */
    const a = new YArray()
    a.push(items)
    return a
@ -84,23 +79,34 @@ export class YArray extends AbstractType {
    this._prelimContent = null
  }

+  /**
+   * @return {YArray<T>}
+   */
  _copy () {
    return new YArray()
  }

  /**
+   * Makes a copy of this data type that can be included somewhere else.
+   *
+   * Note that the content is only readable _after_ it has been included somewhere in the Ydoc.
+   *
   * @return {YArray<T>}
   */
  clone () {
+    /**
+     * @type {YArray<T>}
+     */
    const arr = new YArray()
    arr.insert(0, this.toArray().map(el =>
-      el instanceof AbstractType ? el.clone() : el
+      el instanceof AbstractType ? /** @type {typeof el} */ (el.clone()) : el
    ))
    return arr
  }

  get length () {
-    return this._prelimContent === null ? this._length : this._prelimContent.length
+    this.doc ?? warnPrematureAccess()
+    return this._length
  }

  /**
@ -133,7 +139,7 @@ export class YArray extends AbstractType {
  insert (index, content) {
    if (this.doc !== null) {
      transact(this.doc, transaction => {
-        typeListInsertGenerics(transaction, this, index, content)
+        typeListInsertGenerics(transaction, this, index, /** @type {any} */ (content))
      })
    } else {
      /** @type {Array<any>} */ (this._prelimContent).splice(index, 0, ...content)
@ -150,7 +156,7 @@ export class YArray extends AbstractType {
  push (content) {
    if (this.doc !== null) {
      transact(this.doc, transaction => {
-        typeListPushGenerics(transaction, this, content)
+        typeListPushGenerics(transaction, this, /** @type {any} */ (content))
      })
    } else {
      /** @type {Array<any>} */ (this._prelimContent).push(...content)
@ -158,9 +164,9 @@ export class YArray extends AbstractType {
  }

  /**
-   * Preppends content to this YArray.
+   * Prepends content to this YArray.
   *
-   * @param {Array<T>} content Array of content to preppend.
+   * @param {Array<T>} content Array of content to prepend.
   */
  unshift (content) {
    this.insert(0, content)
@ -202,7 +208,8 @@ export class YArray extends AbstractType {
  }

  /**
-   * Transforms this YArray to a JavaScript Array.
+   * Returns a portion of this YArray into a JavaScript Array selected
+   * from start to end (end not included).
   *
   * @param {number} [start]
   * @param {number} [end]
@ -235,7 +242,7 @@ export class YArray extends AbstractType {
  }

  /**
-   * Executes a provided function on once on overy element of this YArray.
+   * Executes a provided function once on every element of this YArray.
   *
   * @param {function(T,number,YArray<T>):void} f A function to execute on every element of this YArray.
   */
@ -259,9 +266,9 @@ export class YArray extends AbstractType {
 }

 /**
- * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} _decoder
 *
 * @private
 * @function
 */
-export const readYArray = decoder => new YArray()
+export const readYArray = _decoder => new YArray()
--- a/src/types/YMap.js
+++ b/src/types/YMap.js
@ -1,4 +1,3 @@
-
 /**
 * @module YMap
 */
@ -14,6 +13,7 @@ import {
  YMapRefID,
  callTypeObservers,
  transact,
+  warnPrematureAccess,
  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Doc, Transaction, Item // eslint-disable-line
 } from '../internals.js'

@ -41,7 +41,7 @@ export class YMapEvent extends YEvent {
 * A shared Map implementation.
 *
 * @extends AbstractType<YMapEvent<MapType>>
- * @implements {Iterable<MapType>}
+ * @implements {Iterable<[string, MapType]>}
 */
 export class YMap extends AbstractType {
  /**
@ -81,17 +81,27 @@ export class YMap extends AbstractType {
    this._prelimContent = null
  }

+  /**
+   * @return {YMap<MapType>}
+   */
  _copy () {
    return new YMap()
  }

  /**
+   * Makes a copy of this data type that can be included somewhere else.
+   *
+   * Note that the content is only readable _after_ it has been included somewhere in the Ydoc.
+   *
   * @return {YMap<MapType>}
   */
  clone () {
+    /**
+     * @type {YMap<MapType>}
+     */
    const map = new YMap()
    this.forEach((value, key) => {
-      map.set(key, value instanceof AbstractType ? value.clone() : value)
+      map.set(key, value instanceof AbstractType ? /** @type {typeof value} */ (value.clone()) : value)
    })
    return map
  }
@ -112,6 +122,7 @@ export class YMap extends AbstractType {
   * @return {Object<string,any>}
   */
  toJSON () {
+    this.doc ?? warnPrematureAccess()
    /**
     * @type {Object<string,MapType>}
     */
@ -131,7 +142,7 @@ export class YMap extends AbstractType {
   * @return {number}
   */
  get size () {
-    return [...createMapIterator(this._map)].length
+    return [...createMapIterator(this)].length
  }

  /**
@ -140,25 +151,25 @@ export class YMap extends AbstractType {
   * @return {IterableIterator<string>}
   */
  keys () {
-    return iterator.iteratorMap(createMapIterator(this._map), /** @param {any} v */ v => v[0])
+    return iterator.iteratorMap(createMapIterator(this), /** @param {any} v */ v => v[0])
  }

  /**
   * Returns the values for each element in the YMap Type.
   *
-   * @return {IterableIterator<any>}
+   * @return {IterableIterator<MapType>}
   */
  values () {
-    return iterator.iteratorMap(createMapIterator(this._map), /** @param {any} v */ v => v[1].content.getContent()[v[1].length - 1])
+    return iterator.iteratorMap(createMapIterator(this), /** @param {any} v */ v => v[1].content.getContent()[v[1].length - 1])
  }

  /**
   * Returns an Iterator of [key, value] pairs
   *
-   * @return {IterableIterator<any>}
+   * @return {IterableIterator<[string, MapType]>}
   */
  entries () {
-    return iterator.iteratorMap(createMapIterator(this._map), /** @param {any} v */ v => [v[0], v[1].content.getContent()[v[1].length - 1]])
+    return iterator.iteratorMap(createMapIterator(this), /** @param {any} v */ v => /** @type {any} */ ([v[0], v[1].content.getContent()[v[1].length - 1]]))
  }

  /**
@ -167,6 +178,7 @@ export class YMap extends AbstractType {
   * @param {function(MapType,string,YMap<MapType>):void} f A function to execute on every element of this YArray.
   */
  forEach (f) {
+    this.doc ?? warnPrematureAccess()
    this._map.forEach((item, key) => {
      if (!item.deleted) {
        f(item.content.getContent()[item.length - 1], key, this)
@ -177,7 +189,7 @@ export class YMap extends AbstractType {
  /**
   * Returns an Iterator of [key, value] pairs
   *
-   * @return {IterableIterator<any>}
+   * @return {IterableIterator<[string, MapType]>}
   */
  [Symbol.iterator] () {
    return this.entries()
@ -200,14 +212,16 @@ export class YMap extends AbstractType {

  /**
   * Adds or updates an element with a specified key and value.
+   * @template {MapType} VAL
   *
   * @param {string} key The key of the element to add to this YMap
-   * @param {MapType} value The value of the element to add
+   * @param {VAL} value The value of the element to add
+   * @return {VAL}
   */
  set (key, value) {
    if (this.doc !== null) {
      transact(this.doc, transaction => {
-        typeMapSet(transaction, this, key, value)
+        typeMapSet(transaction, this, key, /** @type {any} */ (value))
      })
    } else {
      /** @type {Map<string, any>} */ (this._prelimContent).set(key, value)
@ -241,7 +255,7 @@ export class YMap extends AbstractType {
  clear () {
    if (this.doc !== null) {
      transact(this.doc, transaction => {
-        this.forEach(function (value, key, map) {
+        this.forEach(function (_value, key, map) {
          typeMapDelete(transaction, map, key)
        })
      })
@ -259,9 +273,9 @@ export class YMap extends AbstractType {
 }

 /**
- * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} _decoder
 *
 * @private
 * @function
 */
-export const readYMap = decoder => new YMap()
+export const readYMap = _decoder => new YMap()
--- a/src/types/YText.js
+++ b/src/types/YText.js
@ -1,4 +1,3 @@
-
 /**
 * @module YText
 */
@ -27,6 +26,7 @@ import {
  typeMapGetAll,
  updateMarkerChanges,
  ContentType,
+  warnPrematureAccess,
  ArraySearchMarker, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, ID, Doc, Item, Snapshot, Transaction // eslint-disable-line
 } from '../internals.js'

@ -118,14 +118,15 @@ const findNextPosition = (transaction, pos, count) => {
 * @param {Transaction} transaction
 * @param {AbstractType<any>} parent
 * @param {number} index
+ * @param {boolean} useSearchMarker
 * @return {ItemTextListPosition}
 *
 * @private
 * @function
 */
-const findPosition = (transaction, parent, index) => {
+const findPosition = (transaction, parent, index, useSearchMarker) => {
  const currentAttributes = new Map()
-  const marker = findMarker(parent, index)
+  const marker = useSearchMarker ? findMarker(parent, index) : null
  if (marker) {
    const pos = new ItemTextListPosition(marker.p.left, marker.p, marker.index, currentAttributes)
    return findNextPosition(transaction, pos, index - marker.index)
@ -201,7 +202,7 @@ const minimizeAttributeChanges = (currPos, attributes) => {
  while (true) {
    if (currPos.right === null) {
      break
-    } else if (currPos.right.deleted || (currPos.right.content.constructor === ContentFormat && equalAttrs(attributes[(/** @type {ContentFormat} */ (currPos.right.content)).key] || null, /** @type {ContentFormat} */ (currPos.right.content).value))) {
+    } else if (currPos.right.deleted || (currPos.right.content.constructor === ContentFormat && equalAttrs(attributes[(/** @type {ContentFormat} */ (currPos.right.content)).key] ?? null, /** @type {ContentFormat} */ (currPos.right.content).value))) {
      //
    } else {
      break
@ -227,7 +228,7 @@ const insertAttributes = (transaction, parent, currPos, attributes) => {
  // insert format-start items
  for (const key in attributes) {
    const val = attributes[key]
-    const currentVal = currPos.currentAttributes.get(key) || null
+    const currentVal = currPos.currentAttributes.get(key) ?? null
    if (!equalAttrs(currentVal, val)) {
      // save negated attribute (set null if currentVal undefined)
      negatedAttributes.set(key, currentVal)
@ -251,7 +252,7 @@ const insertAttributes = (transaction, parent, currPos, attributes) => {
 * @function
 **/
 const insertText = (transaction, parent, currPos, text, attributes) => {
-  currPos.currentAttributes.forEach((val, key) => {
+  currPos.currentAttributes.forEach((_val, key) => {
    if (attributes[key] === undefined) {
      attributes[key] = null
    }
@ -363,33 +364,48 @@ const formatText = (transaction, parent, currPos, length, attributes) => {
 * @function
 */
 const cleanupFormattingGap = (transaction, start, curr, startAttributes, currAttributes) => {
-  let end = curr
-  const endAttributes = map.copy(currAttributes)
+  /**
+   * @type {Item|null}
+   */
+  let end = start
+  /**
+   * @type {Map<string,ContentFormat>}
+   */
+  const endFormats = map.create()
  while (end && (!end.countable || end.deleted)) {
    if (!end.deleted && end.content.constructor === ContentFormat) {
-      updateCurrentAttributes(endAttributes, /** @type {ContentFormat} */ (end.content))
+      const cf = /** @type {ContentFormat} */ (end.content)
+      endFormats.set(cf.key, cf)
    }
    end = end.right
  }
  let cleanups = 0
-  let reachedEndOfCurr = false
+  let reachedCurr = false
  while (start !== end) {
    if (curr === start) {
-      reachedEndOfCurr = true
+      reachedCurr = true
    }
    if (!start.deleted) {
      const content = start.content
      switch (content.constructor) {
        case ContentFormat: {
          const { key, value } = /** @type {ContentFormat} */ (content)
-          if ((endAttributes.get(key) || null) !== value || (startAttributes.get(key) || null) === value) {
+          const startAttrValue = startAttributes.get(key) ?? null
+          if (endFormats.get(key) !== content || startAttrValue === value) {
            // Either this format is overwritten or it is not necessary because the attribute already existed.
            start.delete(transaction)
            cleanups++
-            if (!reachedEndOfCurr && (currAttributes.get(key) || null) === value && (startAttributes.get(key) || null) !== value) {
-              currAttributes.delete(key)
+            if (!reachedCurr && (currAttributes.get(key) ?? null) === value && startAttrValue !== value) {
+              if (startAttrValue === null) {
+                currAttributes.delete(key)
+              } else {
+                currAttributes.set(key, startAttrValue)
+              }
            }
          }
+          if (!reachedCurr && !start.deleted) {
+            updateCurrentAttributes(currAttributes, /** @type {ContentFormat} */ (content))
+          }
          break
        }
      }
@ -461,6 +477,56 @@ export const cleanupYTextFormatting = type => {
  return res
 }

+/**
+ * This will be called by the transaction once the event handlers are called to potentially cleanup
+ * formatting attributes.
+ *
+ * @param {Transaction} transaction
+ */
+export const cleanupYTextAfterTransaction = transaction => {
+  /**
+   * @type {Set<YText>}
+   */
+  const needFullCleanup = new Set()
+  // check if another formatting item was inserted
+  const doc = transaction.doc
+  for (const [client, afterClock] of transaction.afterState.entries()) {
+    const clock = transaction.beforeState.get(client) || 0
+    if (afterClock === clock) {
+      continue
+    }
+    iterateStructs(transaction, /** @type {Array<Item|GC>} */ (doc.store.clients.get(client)), clock, afterClock, item => {
+      if (
+        !item.deleted && /** @type {Item} */ (item).content.constructor === ContentFormat && item.constructor !== GC
+      ) {
+        needFullCleanup.add(/** @type {any} */ (item).parent)
+      }
+    })
+  }
+  // cleanup in a new transaction
+  transact(doc, (t) => {
+    iterateDeletedStructs(transaction, transaction.deleteSet, item => {
+      if (item instanceof GC || !(/** @type {YText} */ (item.parent)._hasFormatting) || needFullCleanup.has(/** @type {YText} */ (item.parent))) {
+        return
+      }
+      const parent = /** @type {YText} */ (item.parent)
+      if (item.content.constructor === ContentFormat) {
+        needFullCleanup.add(parent)
+      } else {
+        // If no formatting attribute was inserted or deleted, we can make due with contextless
+        // formatting cleanups.
+        // Contextless: it is not necessary to compute currentAttributes for the affected position.
+        cleanupContextlessFormattingGap(t, item)
+      }
+    })
+    // If a formatting item was inserted, we simply clean the whole type.
+    // We need to compute currentAttributes for the current position anyway.
+    for (const yText of needFullCleanup) {
+      cleanupYTextFormatting(yText)
+    }
+  })
+}
+
 /**
 * @param {Transaction} transaction
 * @param {ItemTextListPosition} currPos
@ -502,7 +568,7 @@ const deleteText = (transaction, currPos, length) => {

 /**
 * 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}
+ * formatting information. For more information visit {@link https://quilljs.com/docs/delta/|Quill Delta}
 *
 * @example
 *   {
@ -616,36 +682,39 @@ export class YTextEvent extends YEvent {
            /**
             * @type {any}
             */
-            let op
+            let op = null
            switch (action) {
              case 'delete':
-                op = { delete: deleteLen }
+                if (deleteLen > 0) {
+                  op = { delete: deleteLen }
+                }
                deleteLen = 0
                break
              case 'insert':
-                op = { insert }
-                if (currentAttributes.size > 0) {
-                  op.attributes = {}
-                  currentAttributes.forEach((value, key) => {
-                    if (value !== null) {
-                      op.attributes[key] = value
-                    }
-                  })
+                if (typeof insert === 'object' || insert.length > 0) {
+                  op = { insert }
+                  if (currentAttributes.size > 0) {
+                    op.attributes = {}
+                    currentAttributes.forEach((value, key) => {
+                      if (value !== null) {
+                        op.attributes[key] = value
+                      }
+                    })
+                  }
                }
                insert = ''
                break
              case 'retain':
-                op = { retain }
-                if (Object.keys(attributes).length > 0) {
-                  op.attributes = {}
-                  for (const key in attributes) {
-                    op.attributes[key] = attributes[key]
+                if (retain > 0) {
+                  op = { retain }
+                  if (!object.isEmpty(attributes)) {
+                    op.attributes = object.assign({}, attributes)
                  }
                }
                retain = 0
                break
            }
-            delta.push(op)
+            if (op) delta.push(op)
            action = null
          }
        }
@ -701,12 +770,12 @@ export class YTextEvent extends YEvent {
              const { key, value } = /** @type {ContentFormat} */ (item.content)
              if (this.adds(item)) {
                if (!this.deletes(item)) {
-                  const curVal = currentAttributes.get(key) || null
+                  const curVal = currentAttributes.get(key) ?? null
                  if (!equalAttrs(curVal, value)) {
                    if (action === 'retain') {
                      addOp()
                    }
-                    if (equalAttrs(value, (oldAttributes.get(key) || null))) {
+                    if (equalAttrs(value, (oldAttributes.get(key) ?? null))) {
                      delete attributes[key]
                    } else {
                      attributes[key] = value
@ -717,7 +786,7 @@ export class YTextEvent extends YEvent {
                }
              } else if (this.deletes(item)) {
                oldAttributes.set(key, value)
-                const curVal = currentAttributes.get(key) || null
+                const curVal = currentAttributes.get(key) ?? null
                if (!equalAttrs(curVal, value)) {
                  if (action === 'retain') {
                    addOp()
@ -791,9 +860,14 @@ export class YText extends AbstractType {
     */
    this._pending = string !== undefined ? [() => this.insert(0, string)] : []
    /**
-     * @type {Array<ArraySearchMarker>}
+     * @type {Array<ArraySearchMarker>|null}
     */
    this._searchMarker = []
+    /**
+     * Whether this YText contains formatting attributes.
+     * This flag is updated when a formatting item is integrated (see ContentFormat.integrate)
+     */
+    this._hasFormatting = false
  }

  /**
@ -802,6 +876,7 @@ export class YText extends AbstractType {
   * @type {number}
   */
  get length () {
+    this.doc ?? warnPrematureAccess()
    return this._length
  }

@ -824,6 +899,10 @@ export class YText extends AbstractType {
  }

  /**
+   * Makes a copy of this data type that can be included somewhere else.
+   *
+   * Note that the content is only readable _after_ it has been included somewhere in the Ydoc.
+   *
   * @return {YText}
   */
  clone () {
@ -841,55 +920,10 @@ export class YText extends AbstractType {
  _callObserver (transaction, parentSubs) {
    super._callObserver(transaction, parentSubs)
    const event = new YTextEvent(this, transaction, parentSubs)
-    const doc = transaction.doc
    callTypeObservers(this, transaction, event)
    // If a remote change happened, we try to cleanup potential formatting duplicates.
-    if (!transaction.local) {
-      // check if another formatting item was inserted
-      let foundFormattingItem = false
-      for (const [client, afterClock] of transaction.afterState.entries()) {
-        const clock = transaction.beforeState.get(client) || 0
-        if (afterClock === clock) {
-          continue
-        }
-        iterateStructs(transaction, /** @type {Array<Item|GC>} */ (doc.store.clients.get(client)), clock, afterClock, item => {
-          if (!item.deleted && /** @type {Item} */ (item).content.constructor === ContentFormat) {
-            foundFormattingItem = true
-          }
-        })
-        if (foundFormattingItem) {
-          break
-        }
-      }
-      if (!foundFormattingItem) {
-        iterateDeletedStructs(transaction, transaction.deleteSet, item => {
-          if (item instanceof GC || foundFormattingItem) {
-            return
-          }
-          if (item.parent === this && item.content.constructor === ContentFormat) {
-            foundFormattingItem = true
-          }
-        })
-      }
-      transact(doc, (t) => {
-        if (foundFormattingItem) {
-          // If a formatting item was inserted, we simply clean the whole type.
-          // We need to compute currentAttributes for the current position anyway.
-          cleanupYTextFormatting(this)
-        } else {
-          // If no formatting attribute was inserted, we can make due with contextless
-          // formatting cleanups.
-          // Contextless: it is not necessary to compute currentAttributes for the affected position.
-          iterateDeletedStructs(t, t.deleteSet, item => {
-            if (item instanceof GC) {
-              return
-            }
-            if (item.parent === this) {
-              cleanupContextlessFormattingGap(t, item)
-            }
-          })
-        }
-      })
+    if (!transaction.local && this._hasFormatting) {
+      transaction._needFormattingCleanup = true
    }
  }

@ -899,6 +933,7 @@ export class YText extends AbstractType {
   * @public
   */
  toString () {
+    this.doc ?? warnPrematureAccess()
    let str = ''
    /**
     * @type {Item|null}
@ -926,8 +961,8 @@ export class YText extends AbstractType {
  /**
   * Apply a {@link Delta} on this shared YText type.
   *
-   * @param {any} delta The changes to apply on this element.
-   * @param {object}  [opts]
+   * @param {Array<any>} delta The changes to apply on this element.
+   * @param {object}  opts
   * @param {boolean} [opts.sanitize] Sanitize input delta. Removes ending newlines if set to true.
   *
   *
@ -972,6 +1007,7 @@ export class YText extends AbstractType {
   * @public
   */
  toDelta (snapshot, prevSnapshot, computeYChange) {
+    this.doc ?? warnPrematureAccess()
    /**
     * @type{Array<any>}
     */
@ -1003,15 +1039,7 @@ export class YText extends AbstractType {
        str = ''
      }
    }
-    // snapshots are merged again after the transaction, so we need to keep the
-    // transalive until we are done
-    transact(doc, transaction => {
-      if (snapshot) {
-        splitSnapshotAffectedStructs(transaction, snapshot)
-      }
-      if (prevSnapshot) {
-        splitSnapshotAffectedStructs(transaction, prevSnapshot)
-      }
+    const computeDelta = () => {
      while (n !== null) {
        if (isVisible(n, snapshot) || (prevSnapshot !== undefined && isVisible(n, prevSnapshot))) {
          switch (n.content.constructor) {
@ -1064,7 +1092,22 @@ export class YText extends AbstractType {
        n = n.right
      }
      packStr()
-    }, 'cleanup')
+    }
+    if (snapshot || prevSnapshot) {
+      // snapshots are merged again after the transaction, so we need to keep the
+      // transaction alive until we are done
+      transact(doc, transaction => {
+        if (snapshot) {
+          splitSnapshotAffectedStructs(transaction, snapshot)
+        }
+        if (prevSnapshot) {
+          splitSnapshotAffectedStructs(transaction, prevSnapshot)
+        }
+        computeDelta()
+      }, 'cleanup')
+    } else {
+      computeDelta()
+    }
    return ops
  }

@ -1085,7 +1128,7 @@ export class YText extends AbstractType {
    const y = this.doc
    if (y !== null) {
      transact(y, transaction => {
-        const pos = findPosition(transaction, this, index)
+        const pos = findPosition(transaction, this, index, !attributes)
        if (!attributes) {
          attributes = {}
          // @ts-ignore
@ -1103,20 +1146,20 @@ export class YText extends AbstractType {
   *
   * @param {number} index The index to insert the embed at.
   * @param {Object | AbstractType<any>} embed The Object that represents the embed.
-   * @param {TextAttributes} attributes Attribute information to apply on the
+   * @param {TextAttributes} [attributes] Attribute information to apply on the
   *                                    embed
   *
   * @public
   */
-  insertEmbed (index, embed, attributes = {}) {
+  insertEmbed (index, embed, attributes) {
    const y = this.doc
    if (y !== null) {
      transact(y, transaction => {
-        const pos = findPosition(transaction, this, index)
-        insertText(transaction, this, pos, embed, attributes)
+        const pos = findPosition(transaction, this, index, !attributes)
+        insertText(transaction, this, pos, embed, attributes || {})
      })
    } else {
-      /** @type {Array<function>} */ (this._pending).push(() => this.insertEmbed(index, embed, attributes))
+      /** @type {Array<function>} */ (this._pending).push(() => this.insertEmbed(index, embed, attributes || {}))
    }
  }

@ -1135,7 +1178,7 @@ export class YText extends AbstractType {
    const y = this.doc
    if (y !== null) {
      transact(y, transaction => {
-        deleteText(transaction, findPosition(transaction, this, index), length)
+        deleteText(transaction, findPosition(transaction, this, index, true), length)
      })
    } else {
      /** @type {Array<function>} */ (this._pending).push(() => this.delete(index, length))
@ -1159,7 +1202,7 @@ export class YText extends AbstractType {
    const y = this.doc
    if (y !== null) {
      transact(y, transaction => {
-        const pos = findPosition(transaction, this, index)
+        const pos = findPosition(transaction, this, index, false)
        if (pos.right === null) {
          return
        }
@ -1229,12 +1272,11 @@ export class YText extends AbstractType {
   *
   * @note Xml-Text nodes don't have attributes. You can use this feature to assign properties to complete text-blocks.
   *
-   * @param {Snapshot} [snapshot]
   * @return {Object<string, any>} A JSON Object that describes the attributes.
   *
   * @public
   */
-  getAttributes (snapshot) {
+  getAttributes () {
    return typeMapGetAll(this)
  }

@ -1247,10 +1289,10 @@ export class YText extends AbstractType {
 }

 /**
- * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} _decoder
 * @return {YText}
 *
 * @private
 * @function
 */
-export const readYText = decoder => new YText()
+export const readYText = _decoder => new YText()
--- a/src/types/YXmlElement.js
+++ b/src/types/YXmlElement.js
@ -1,3 +1,4 @@
+import * as object from 'lib0/object'

 import {
  YXmlFragment,
@ -7,17 +8,24 @@ import {
  typeMapSet,
  typeMapGet,
  typeMapGetAll,
+  typeMapGetAllSnapshot,
  typeListForEach,
  YXmlElementRefID,
-  YXmlText, ContentType, AbstractType, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Snapshot, Doc, Item // eslint-disable-line
+  Snapshot, YXmlText, ContentType, AbstractType, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Doc, Item // eslint-disable-line
 } from '../internals.js'

+/**
+ * @typedef {Object|number|null|Array<any>|string|Uint8Array|AbstractType<any>} ValueTypes
+ */
+
 /**
 * An YXmlElement imitates the behavior of a
- * {@link https://developer.mozilla.org/en-US/docs/Web/API/Element|Dom Element}.
+ * 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
+ *
+ * @template {{ [key: string]: ValueTypes }} [KV={ [key: string]: string }]
 */
 export class YXmlElement extends YXmlFragment {
  constructor (nodeName = 'UNDEFINED') {
@ -73,14 +81,23 @@ export class YXmlElement extends YXmlFragment {
  }

  /**
-   * @return {YXmlElement}
+   * Makes a copy of this data type that can be included somewhere else.
+   *
+   * Note that the content is only readable _after_ it has been included somewhere in the Ydoc.
+   *
+   * @return {YXmlElement<KV>}
   */
  clone () {
+    /**
+     * @type {YXmlElement<KV>}
+     */
    const el = new YXmlElement(this.nodeName)
    const attrs = this.getAttributes()
-    for (const key in attrs) {
-      el.setAttribute(key, attrs[key])
-    }
+    object.forEach(attrs, (value, key) => {
+      if (typeof value === 'string') {
+        el.setAttribute(key, value)
+      }
+    })
    // @ts-ignore
    el.insert(0, this.toArray().map(item => item instanceof AbstractType ? item.clone() : item))
    return el
@ -116,7 +133,7 @@ export class YXmlElement extends YXmlFragment {
  /**
   * Removes an attribute from this YXmlElement.
   *
-   * @param {String} attributeName The attribute name that is to be removed.
+   * @param {string} attributeName The attribute name that is to be removed.
   *
   * @public
   */
@ -133,8 +150,10 @@ export class YXmlElement extends YXmlFragment {
  /**
   * 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.
+   * @template {keyof KV & string} KEY
+   *
+   * @param {KEY} attributeName The attribute name that is to be set.
+   * @param {KV[KEY]} attributeValue The attribute value that is to be set.
   *
   * @public
   */
@ -151,9 +170,11 @@ export class YXmlElement extends YXmlFragment {
  /**
   * Returns an attribute value that belongs to the attribute name.
   *
-   * @param {String} attributeName The attribute name that identifies the
+   * @template {keyof KV & string} KEY
+   *
+   * @param {KEY} attributeName The attribute name that identifies the
   *                               queried value.
-   * @return {String} The queried attribute value.
+   * @return {KV[KEY]|undefined} The queried attribute value.
   *
   * @public
   */
@ -164,7 +185,7 @@ export class YXmlElement extends YXmlFragment {
  /**
   * Returns whether an attribute exists
   *
-   * @param {String} attributeName The attribute name to check for existence.
+   * @param {string} attributeName The attribute name to check for existence.
   * @return {boolean} whether the attribute exists.
   *
   * @public
@ -176,12 +197,13 @@ export class YXmlElement extends YXmlFragment {
  /**
   * Returns all attribute name/value pairs in a JSON Object.
   *
-   * @return {Object<string, any>} A JSON Object that describes the attributes.
+   * @param {Snapshot} [snapshot]
+   * @return {{ [Key in Extract<keyof KV,string>]?: KV[Key]}} A JSON Object that describes the attributes.
   *
   * @public
   */
-  getAttributes () {
-    return typeMapGetAll(this)
+  getAttributes (snapshot) {
+    return /** @type {any} */ (snapshot ? typeMapGetAllSnapshot(this, snapshot) : typeMapGetAll(this))
  }

  /**
@ -203,7 +225,10 @@ export class YXmlElement extends YXmlFragment {
    const dom = _document.createElement(this.nodeName)
    const attrs = this.getAttributes()
    for (const key in attrs) {
-      dom.setAttribute(key, attrs[key])
+      const value = attrs[key]
+      if (typeof value === 'string') {
+        dom.setAttribute(key, value)
+      }
    }
    typeListForEach(this, yxml => {
      dom.appendChild(yxml.toDOM(_document, hooks, binding))
--- a/src/types/YXmlEvent.js
+++ b/src/types/YXmlEvent.js
@ -1,4 +1,3 @@
-
 import {
  YEvent,
  YXmlText, YXmlElement, YXmlFragment, Transaction // eslint-disable-line
@ -13,7 +12,7 @@ export class YXmlEvent extends YEvent {
   * @param {YXmlElement|YXmlText|YXmlFragment} target The target on which the event is created.
   * @param {Set<string|null>} subs The set of changed attributes. `null` is included if the
   *                   child list changed.
-   * @param {Transaction} transaction The transaction instance with wich the
+   * @param {Transaction} transaction The transaction instance with which the
   *                                  change was created.
   */
  constructor (target, subs, transaction) {
--- a/src/types/YXmlFragment.js
+++ b/src/types/YXmlFragment.js
@ -17,10 +17,12 @@ import {
  transact,
  typeListGet,
  typeListSlice,
-  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Doc, ContentType, Transaction, Item, YXmlText, YXmlHook, Snapshot // eslint-disable-line
+  warnPrematureAccess,
+  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Doc, ContentType, Transaction, Item, YXmlText, YXmlHook // eslint-disable-line
 } from '../internals.js'

 import * as error from 'lib0/error'
+import * as array from 'lib0/array'

 /**
 * Define the elements to which a set of CSS queries apply.
@ -65,6 +67,7 @@ export class YXmlTreeWalker {
     */
    this._currentNode = /** @type {Item} */ (root._start)
    this._firstCall = true
+    root.doc ?? warnPrematureAccess()
  }

  [Symbol.iterator] () {
@ -93,8 +96,12 @@ export class YXmlTreeWalker {
        } else {
          // walk right or up in the tree
          while (n !== null) {
-            if (n.right !== null) {
-              n = n.right
+            /**
+             * @type {Item | null}
+             */
+            const nxt = n.next
+            if (nxt !== null) {
+              n = nxt
              break
            } else if (n.parent === this._root) {
              n = null
@ -162,6 +169,10 @@ export class YXmlFragment extends AbstractType {
  }

  /**
+   * Makes a copy of this data type that can be included somewhere else.
+   *
+   * Note that the content is only readable _after_ it has been included somewhere in the Ydoc.
+   *
   * @return {YXmlFragment}
   */
  clone () {
@ -172,6 +183,7 @@ export class YXmlFragment extends AbstractType {
  }

  get length () {
+    this.doc ?? warnPrematureAccess()
    return this._prelimContent === null ? this._length : this._prelimContent.length
  }

@ -237,7 +249,7 @@ export class YXmlFragment extends AbstractType {
  querySelectorAll (query) {
    query = query.toUpperCase()
    // @ts-ignore
-    return Array.from(new YXmlTreeWalker(this, element => element.nodeName && element.nodeName.toUpperCase() === query))
+    return array.from(new YXmlTreeWalker(this, element => element.nodeName && element.nodeName.toUpperCase() === query))
  }

  /**
@ -375,9 +387,9 @@ export class YXmlFragment extends AbstractType {
  }

  /**
-   * Preppends content to this YArray.
+   * Prepends content to this YArray.
   *
-   * @param {Array<YXmlElement|YXmlText>} content Array of content to preppend.
+   * @param {Array<YXmlElement|YXmlText>} content Array of content to prepend.
   */
  unshift (content) {
    this.insert(0, content)
@ -394,7 +406,8 @@ export class YXmlFragment extends AbstractType {
  }

  /**
-   * Transforms this YArray to a JavaScript Array.
+   * Returns a portion of this YXmlFragment into a JavaScript Array selected
+   * from start to end (end not included).
   *
   * @param {number} [start]
   * @param {number} [end]
@ -405,9 +418,9 @@ export class YXmlFragment extends AbstractType {
  }

  /**
-   * Executes a provided function on once on overy child element.
+   * Executes a provided function on once on every child element.
   *
-   * @param {function(YXmlElement|YXmlText,number, typeof this):void} f A function to execute on every element of this YArray.
+   * @param {function(YXmlElement|YXmlText,number, typeof self):void} f A function to execute on every element of this YArray.
   */
  forEach (f) {
    typeListForEach(this, f)
@ -427,10 +440,10 @@ export class YXmlFragment extends AbstractType {
 }

 /**
- * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} _decoder
 * @return {YXmlFragment}
 *
 * @private
 * @function
 */
-export const readYXmlFragment = decoder => new YXmlFragment()
+export const readYXmlFragment = _decoder => new YXmlFragment()
--- a/src/types/YXmlHook.js
+++ b/src/types/YXmlHook.js
@ -1,4 +1,3 @@
-
 import {
  YMap,
  YXmlHookRefID,
@ -30,6 +29,10 @@ export class YXmlHook extends YMap {
  }

  /**
+   * Makes a copy of this data type that can be included somewhere else.
+   *
+   * Note that the content is only readable _after_ it has been included somewhere in the Ydoc.
+   *
   * @return {YXmlHook}
   */
  clone () {
--- a/src/types/YXmlText.js
+++ b/src/types/YXmlText.js
@ -1,4 +1,3 @@
-
 import {
  YText,
  YXmlTextRefID,
@ -31,6 +30,10 @@ export class YXmlText extends YText {
  }

  /**
+   * Makes a copy of this data type that can be included somewhere else.
+   *
+   * Note that the content is only readable _after_ it has been included somewhere in the Ydoc.
+   *
   * @return {YXmlText}
   */
  clone () {
--- a/src/utils/AbstractConnector.js
+++ b/src/utils/AbstractConnector.js
@ -1,5 +1,4 @@
-
-import { Observable } from 'lib0/observable'
+import { ObservableV2 } from 'lib0/observable'

 import {
  Doc // eslint-disable-line
@ -11,9 +10,9 @@ import {
 * @note This interface is experimental and it is not advised to actually inherit this class.
 *       It just serves as typing information.
 *
- * @extends {Observable<any>}
+ * @extends {ObservableV2<any>}
 */
-export class AbstractConnector extends Observable {
+export class AbstractConnector extends ObservableV2 {
  /**
   * @param {Doc} ydoc
   * @param {any} awareness
--- a/src/utils/DeleteSet.js
+++ b/src/utils/DeleteSet.js
@ -1,4 +1,3 @@
-
 import {
  findIndexSS,
  getState,
@ -171,7 +170,7 @@ export const mergeDeleteSets = dss => {
 * @function
 */
 export const addToDeleteSet = (ds, client, clock, length) => {
-  map.setIfUndefined(ds.clients, client, () => []).push(new DeleteItem(clock, length))
+  map.setIfUndefined(ds.clients, client, () => /** @type {Array<DeleteItem>} */ ([])).push(new DeleteItem(clock, length))
 }

 export const createDeleteSet = () => new DeleteSet()
@ -219,17 +218,21 @@ export const createDeleteSetFromStructStore = ss => {
 */
 export const writeDeleteSet = (encoder, ds) => {
  encoding.writeVarUint(encoder.restEncoder, ds.clients.size)
-  ds.clients.forEach((dsitems, client) => {
-    encoder.resetDsCurVal()
-    encoding.writeVarUint(encoder.restEncoder, client)
-    const len = dsitems.length
-    encoding.writeVarUint(encoder.restEncoder, len)
-    for (let i = 0; i < len; i++) {
-      const item = dsitems[i]
-      encoder.writeDsClock(item.clock)
-      encoder.writeDsLen(item.len)
-    }
-  })
+
+  // Ensure that the delete set is written in a deterministic order
+  array.from(ds.clients.entries())
+    .sort((a, b) => b[0] - a[0])
+    .forEach(([client, dsitems]) => {
+      encoder.resetDsCurVal()
+      encoding.writeVarUint(encoder.restEncoder, client)
+      const len = dsitems.length
+      encoding.writeVarUint(encoder.restEncoder, len)
+      for (let i = 0; i < len; i++) {
+        const item = dsitems[i]
+        encoder.writeDsClock(item.clock)
+        encoder.writeDsLen(item.len)
+      }
+    })
 }

 /**
@ -247,7 +250,7 @@ export const readDeleteSet = decoder => {
    const client = decoding.readVarUint(decoder.restDecoder)
    const numberOfDeletes = decoding.readVarUint(decoder.restDecoder)
    if (numberOfDeletes > 0) {
-      const dsField = map.setIfUndefined(ds.clients, client, () => [])
+      const dsField = map.setIfUndefined(ds.clients, client, () => /** @type {Array<DeleteItem>} */ ([]))
      for (let i = 0; i < numberOfDeletes; i++) {
        dsField.push(new DeleteItem(decoder.readDsClock(), decoder.readDsLen()))
      }
@ -324,3 +327,23 @@ export const readAndApplyDeleteSet = (decoder, transaction, store) => {
  }
  return null
 }
+
+/**
+ * @param {DeleteSet} ds1
+ * @param {DeleteSet} ds2
+ */
+export const equalDeleteSets = (ds1, ds2) => {
+  if (ds1.clients.size !== ds2.clients.size) return false
+  for (const [client, deleteItems1] of ds1.clients.entries()) {
+    const deleteItems2 = /** @type {Array<import('../internals.js').DeleteItem>} */ (ds2.clients.get(client))
+    if (deleteItems2 === undefined || deleteItems1.length !== deleteItems2.length) return false
+    for (let i = 0; i < deleteItems1.length; i++) {
+      const di1 = deleteItems1[i]
+      const di2 = deleteItems2[i]
+      if (di1.clock !== di2.clock || di1.len !== di2.len) {
+        return false
+      }
+    }
+  }
+  return true
+}
--- a/src/utils/Doc.js
+++ b/src/utils/Doc.js
@ -8,12 +8,13 @@ import {
  YArray,
  YText,
  YMap,
+  YXmlElement,
  YXmlFragment,
  transact,
  ContentDoc, Item, Transaction, YEvent // eslint-disable-line
 } from '../internals.js'

-import { Observable } from 'lib0/observable'
+import { ObservableV2 } from 'lib0/observable'
 import * as random from 'lib0/random'
 import * as map from 'lib0/map'
 import * as array from 'lib0/array'
@ -33,12 +34,28 @@ export const generateNewClientId = random.uint32
 */

 /**
- * A Yjs instance handles the state of shared data.
- * @extends Observable<string>
+ * @typedef {Object} DocEvents
+ * @property {function(Doc):void} DocEvents.destroy
+ * @property {function(Doc):void} DocEvents.load
+ * @property {function(boolean, Doc):void} DocEvents.sync
+ * @property {function(Uint8Array, any, Doc, Transaction):void} DocEvents.update
+ * @property {function(Uint8Array, any, Doc, Transaction):void} DocEvents.updateV2
+ * @property {function(Doc):void} DocEvents.beforeAllTransactions
+ * @property {function(Transaction, Doc):void} DocEvents.beforeTransaction
+ * @property {function(Transaction, Doc):void} DocEvents.beforeObserverCalls
+ * @property {function(Transaction, Doc):void} DocEvents.afterTransaction
+ * @property {function(Transaction, Doc):void} DocEvents.afterTransactionCleanup
+ * @property {function(Doc, Array<Transaction>):void} DocEvents.afterAllTransactions
+ * @property {function({ loaded: Set<Doc>, added: Set<Doc>, removed: Set<Doc> }, Doc, Transaction):void} DocEvents.subdocs
 */
-export class Doc extends Observable {
+
+/**
+ * A Yjs instance handles the state of shared data.
+ * @extends ObservableV2<DocEvents>
+ */
+export class Doc extends ObservableV2 {
  /**
-   * @param {DocOpts} [opts] configuration
+   * @param {DocOpts} opts configuration
   */
  constructor ({ guid = random.uuidv4(), collectionid = null, gc = true, gcFilter = () => true, meta = null, autoLoad = false, shouldLoad = true } = {}) {
    super()
@ -72,13 +89,58 @@ export class Doc extends Observable {
    this.shouldLoad = shouldLoad
    this.autoLoad = autoLoad
    this.meta = meta
+    /**
+     * This is set to true when the persistence provider loaded the document from the database or when the `sync` event fires.
+     * Note that not all providers implement this feature. Provider authors are encouraged to fire the `load` event when the doc content is loaded from the database.
+     *
+     * @type {boolean}
+     */
    this.isLoaded = false
+    /**
+     * This is set to true when the connection provider has successfully synced with a backend.
+     * Note that when using peer-to-peer providers this event may not provide very useful.
+     * Also note that not all providers implement this feature. Provider authors are encouraged to fire
+     * the `sync` event when the doc has been synced (with `true` as a parameter) or if connection is
+     * lost (with false as a parameter).
+     */
+    this.isSynced = false
+    this.isDestroyed = false
+    /**
+     * Promise that resolves once the document has been loaded from a persistence provider.
+     */
    this.whenLoaded = promise.create(resolve => {
      this.on('load', () => {
        this.isLoaded = true
        resolve(this)
      })
    })
+    const provideSyncedPromise = () => promise.create(resolve => {
+      /**
+       * @param {boolean} isSynced
+       */
+      const eventHandler = (isSynced) => {
+        if (isSynced === undefined || isSynced === true) {
+          this.off('sync', eventHandler)
+          resolve()
+        }
+      }
+      this.on('sync', eventHandler)
+    })
+    this.on('sync', isSynced => {
+      if (isSynced === false && this.isSynced) {
+        this.whenSynced = provideSyncedPromise()
+      }
+      this.isSynced = isSynced === undefined || isSynced === true
+      if (this.isSynced && !this.isLoaded) {
+        this.emit('load', [this])
+      }
+    })
+    /**
+     * Promise that resolves once the document has been synced with a backend.
+     * This promise is recreated when the connection is lost.
+     * Note the documentation about the `isSynced` property.
+     */
+    this.whenSynced = provideSyncedPromise()
  }

  /**
@ -103,7 +165,7 @@ export class Doc extends Observable {
  }

  getSubdocGuids () {
-    return new Set(Array.from(this.subdocs).map(doc => doc.guid))
+    return new Set(array.from(this.subdocs).map(doc => doc.guid))
  }

  /**
@ -112,42 +174,45 @@ export class Doc extends Observable {
   * that happened inside of the transaction are sent as one message to the
   * other peers.
   *
-   * @param {function(Transaction):void} f The function that should be executed as a transaction
+   * @template T
+   * @param {function(Transaction):T} f The function that should be executed as a transaction
   * @param {any} [origin] Origin of who started the transaction. Will be stored on transaction.origin
+   * @return T
   *
   * @public
   */
  transact (f, origin = null) {
-    transact(this, f, origin)
+    return transact(this, f, origin)
  }

  /**
   * Define a shared data type.
   *
-   * Multiple calls of `y.get(name, TypeConstructor)` yield the same result
+   * Multiple calls of `ydoc.get(name, TypeConstructor)` yield the same result
   * and do not overwrite each other. I.e.
-   * `y.define(name, Y.Array) === y.define(name, Y.Array)`
+   * `ydoc.get(name, Y.Array) === ydoc.get(name, Y.Array)`
   *
-   * After this method is called, the type is also available on `y.share.get(name)`.
+   * After this method is called, the type is also available on `ydoc.share.get(name)`.
   *
   * *Best Practices:*
-   * Define all types right after the Yjs instance is created and store them in a separate object.
+   * Define all types right after the Y.Doc instance is created and store them in a separate object.
   * Also use the typed methods `getText(name)`, `getArray(name)`, ..
   *
+   * @template {typeof AbstractType<any>} Type
   * @example
-   *   const y = new Y(..)
+   *   const ydoc = new Y.Doc(..)
   *   const appState = {
-   *     document: y.getText('document')
-   *     comments: y.getArray('comments')
+   *     document: ydoc.getText('document')
+   *     comments: ydoc.getArray('comments')
   *   }
   *
   * @param {string} name
-   * @param {Function} TypeConstructor The constructor of the type definition. E.g. Y.Text, Y.Array, Y.Map, ...
-   * @return {AbstractType<any>} The created type. Constructed with TypeConstructor
+   * @param {Type} TypeConstructor The constructor of the type definition. E.g. Y.Text, Y.Array, Y.Map, ...
+   * @return {InstanceType<Type>} The created type. Constructed with TypeConstructor
   *
   * @public
   */
-  get (name, TypeConstructor = AbstractType) {
+  get (name, TypeConstructor = /** @type {any} */ (AbstractType)) {
    const type = map.setIfUndefined(this.share, name, () => {
      // @ts-ignore
      const t = new TypeConstructor()
@ -173,12 +238,12 @@ export class Doc extends Observable {
        t._length = type._length
        this.share.set(name, t)
        t._integrate(this, null)
-        return t
+        return /** @type {InstanceType<Type>} */ (t)
      } else {
        throw new Error(`Type with the name ${name} has already been defined with a different constructor`)
      }
    }
-    return type
+    return /** @type {InstanceType<Type>} */ (type)
  }

  /**
@ -189,8 +254,7 @@ export class Doc extends Observable {
   * @public
   */
  getArray (name = '') {
-    // @ts-ignore
-    return this.get(name, YArray)
+    return /** @type {YArray<T>} */ (this.get(name, YArray))
  }

  /**
@ -200,7 +264,6 @@ export class Doc extends Observable {
   * @public
   */
  getText (name = '') {
-    // @ts-ignore
    return this.get(name, YText)
  }

@ -212,8 +275,17 @@ export class Doc extends Observable {
   * @public
   */
  getMap (name = '') {
-    // @ts-ignore
-    return this.get(name, YMap)
+    return /** @type {YMap<T>} */ (this.get(name, YMap))
+  }
+
+  /**
+   * @param {string} [name]
+   * @return {YXmlElement}
+   *
+   * @public
+   */
+  getXmlElement (name = '') {
+    return /** @type {YXmlElement<{[key:string]:string}>} */ (this.get(name, YXmlElement))
  }

  /**
@ -223,7 +295,6 @@ export class Doc extends Observable {
   * @public
   */
  getXmlFragment (name = '') {
-    // @ts-ignore
    return this.get(name, YXmlFragment)
  }

@ -252,6 +323,7 @@ export class Doc extends Observable {
   * Emit `destroy` event and unregister all event handlers.
   */
  destroy () {
+    this.isDestroyed = true
    array.from(this.subdocs).forEach(subdoc => subdoc.destroy())
    const item = this._item
    if (item !== null) {
@ -267,24 +339,9 @@ export class Doc extends Observable {
        transaction.subdocsRemoved.add(this)
      }, null, true)
    }
-    this.emit('destroyed', [true])
+    // @ts-ignore
+    this.emit('destroyed', [true]) // DEPRECATED!
    this.emit('destroy', [this])
    super.destroy()
  }
-
-  /**
-   * @param {string} eventName
-   * @param {function(...any):any} f
-   */
-  on (eventName, f) {
-    super.on(eventName, f)
-  }
-
-  /**
-   * @param {string} eventName
-   * @param {function} f
-   */
-  off (eventName, f) {
-    super.off(eventName, f)
-  }
 }
--- a/src/utils/ID.js
+++ b/src/utils/ID.js
@ -1,4 +1,3 @@
-
 import { AbstractType } from '../internals.js' // eslint-disable-line

 import * as decoding from 'lib0/decoding'
--- a/src/utils/PermanentUserData.js
+++ b/src/utils/PermanentUserData.js
@ -1,4 +1,3 @@
-
 import {
  YArray,
  YMap,
@ -63,7 +62,7 @@ export class PermanentUserData {
        initUser(storeType.get(userDescription), userDescription)
      )
    })
-    // add intial data
+    // add initial data
    storeType.forEach(initUser)
  }

@ -71,7 +70,7 @@ export class PermanentUserData {
   * @param {Doc} doc
   * @param {number} clientid
   * @param {string} userDescription
-   * @param {Object} [conf]
+   * @param {Object} conf
   * @param {function(Transaction, DeleteSet):boolean} [conf.filter]
   */
  setUserMapping (doc, clientid, userDescription, { filter = () => true } = {}) {
@ -84,7 +83,7 @@ export class PermanentUserData {
      users.set(userDescription, user)
    }
    user.get('ids').push([clientid])
-    users.observe(event => {
+    users.observe(_event => {
      setTimeout(() => {
        const userOverwrite = users.get(userDescription)
        if (userOverwrite !== user) {
--- a/src/utils/RelativePosition.js
+++ b/src/utils/RelativePosition.js
@ -1,4 +1,3 @@
-
 import {
  writeID,
  readID,
@ -9,7 +8,8 @@ import {
  createID,
  ContentType,
  followRedone,
-  ID, Doc, AbstractType // eslint-disable-line
+  getItem,
+  StructStore, ID, Doc, AbstractType, // eslint-disable-line
 } from '../internals.js'

 import * as encoding from 'lib0/encoding'
@ -66,7 +66,7 @@ export class RelativePosition {
     * after the meant position.
     * I.e. position 1 in 'ab' is associated to character 'b'.
     *
-     * If assoc < 0, then the relative position is associated to the caharacter
+     * If assoc < 0, then the relative position is associated to the character
     * before the meant position.
     *
     * @type {number}
@ -102,7 +102,7 @@ export const relativePositionToJSON = rpos => {
 *
 * @function
 */
-export const createRelativePositionFromJSON = json => new RelativePosition(json.type == null ? null : createID(json.type.client, json.type.clock), json.tname || null, json.item == null ? null : createID(json.item.client, json.item.clock), json.assoc == null ? 0 : json.assoc)
+export const createRelativePositionFromJSON = json => new RelativePosition(json.type == null ? null : createID(json.type.client, json.type.clock), json.tname ?? null, json.item == null ? null : createID(json.item.client, json.item.clock), json.assoc == null ? 0 : json.assoc)

 export class AbsolutePosition {
  /**
@ -257,13 +257,36 @@ export const readRelativePosition = decoder => {
 export const decodeRelativePosition = uint8Array => readRelativePosition(decoding.createDecoder(uint8Array))

 /**
+ * @param {StructStore} store
+ * @param {ID} id
+ */
+const getItemWithOffset = (store, id) => {
+  const item = getItem(store, id)
+  const diff = id.clock - item.id.clock
+  return {
+    item, diff
+  }
+}
+
+/**
+ * Transform a relative position to an absolute position.
+ *
+ * If you want to share the relative position with other users, you should set
+ * `followUndoneDeletions` to false to get consistent results across all clients.
+ *
+ * When calculating the absolute position, we try to follow the "undone deletions". This yields
+ * better results for the user who performed undo. However, only the user who performed the undo
+ * will get the better results, the other users don't know which operations recreated a deleted
+ * range of content. There is more information in this ticket: https://github.com/yjs/yjs/issues/638
+ *
 * @param {RelativePosition} rpos
 * @param {Doc} doc
+ * @param {boolean} followUndoneDeletions - whether to follow undone deletions - see https://github.com/yjs/yjs/issues/638
 * @return {AbsolutePosition|null}
 *
 * @function
 */
-export const createAbsolutePositionFromRelativePosition = (rpos, doc) => {
+export const createAbsolutePositionFromRelativePosition = (rpos, doc, followUndoneDeletions = true) => {
  const store = doc.store
  const rightID = rpos.item
  const typeID = rpos.type
@ -275,7 +298,7 @@ export const createAbsolutePositionFromRelativePosition = (rpos, doc) => {
    if (getState(store, rightID.client) <= rightID.clock) {
      return null
    }
-    const res = followRedone(store, rightID)
+    const res = followUndoneDeletions ? followRedone(store, rightID) : getItemWithOffset(store, rightID)
    const right = res.item
    if (!(right instanceof Item)) {
      return null
@ -299,7 +322,7 @@ export const createAbsolutePositionFromRelativePosition = (rpos, doc) => {
        // type does not exist yet
        return null
      }
-      const { item } = followRedone(store, typeID)
+      const { item } = followUndoneDeletions ? followRedone(store, typeID) : { item: getItem(store, typeID) }
      if (item instanceof Item && item.content instanceof ContentType) {
        type = item.content.type
      } else {
--- a/src/utils/Snapshot.js
+++ b/src/utils/Snapshot.js
@ -1,4 +1,3 @@
-
 import {
  isDeleted,
  createDeleteSetFromStructStore,
@ -15,7 +14,10 @@ import {
  findIndexSS,
  UpdateEncoderV2,
  applyUpdateV2,
-  DSEncoderV1, DSEncoderV2, DSDecoderV1, DSDecoderV2, Transaction, Doc, DeleteSet, Item // eslint-disable-line
+  LazyStructReader,
+  equalDeleteSets,
+  UpdateDecoderV1, UpdateDecoderV2, DSEncoderV1, DSEncoderV2, DSDecoderV1, DSDecoderV2, Transaction, Doc, DeleteSet, Item, // eslint-disable-line
+  mergeDeleteSets
 } from '../internals.js'

 import * as map from 'lib0/map'
@ -147,12 +149,20 @@ export const splitSnapshotAffectedStructs = (transaction, snapshot) => {
        getItemCleanStart(transaction, createID(client, clock))
      }
    })
-    iterateDeletedStructs(transaction, snapshot.ds, item => {})
+    iterateDeletedStructs(transaction, snapshot.ds, _item => {})
    meta.add(snapshot)
  }
 }

 /**
+ * @example
+ *  const ydoc = new Y.Doc({ gc: false })
+ *  ydoc.getText().insert(0, 'world!')
+ *  const snapshot = Y.snapshot(ydoc)
+ *  ydoc.getText().insert(0, 'hello ')
+ *  const restored = Y.createDocFromSnapshot(ydoc, snapshot)
+ *  assert(restored.getText().toString() === 'world!')
+ *
 * @param {Doc} originDoc
 * @param {Snapshot} snapshot
 * @param {Doc} [newDoc] Optionally, you may define the Yjs document that receives the data from originDoc
@ -161,7 +171,7 @@ export const splitSnapshotAffectedStructs = (transaction, snapshot) => {
 export const createDocFromSnapshot = (originDoc, snapshot, newDoc = new Doc()) => {
  if (originDoc.gc) {
    // we should not try to restore a GC-ed document, because some of the restored items might have their content deleted
-    throw new Error('originDoc must not be garbage collected')
+    throw new Error('Garbage-collection must be disabled in `originDoc`!')
  }
  const { sv, ds } = snapshot

@ -199,3 +209,28 @@ export const createDocFromSnapshot = (originDoc, snapshot, newDoc = new Doc()) =
  applyUpdateV2(newDoc, encoder.toUint8Array(), 'snapshot')
  return newDoc
 }
+
+/**
+ * @param {Snapshot} snapshot
+ * @param {Uint8Array} update
+ * @param {typeof UpdateDecoderV2 | typeof UpdateDecoderV1} [YDecoder]
+ */
+export const snapshotContainsUpdateV2 = (snapshot, update, YDecoder = UpdateDecoderV2) => {
+  const structs = []
+  const updateDecoder = new YDecoder(decoding.createDecoder(update))
+  const lazyDecoder = new LazyStructReader(updateDecoder, false)
+  for (let curr = lazyDecoder.curr; curr !== null; curr = lazyDecoder.next()) {
+    structs.push(curr)
+    if ((snapshot.sv.get(curr.id.client) || 0) < curr.id.clock + curr.length) {
+      return false
+    }
+  }
+  const mergedDS = mergeDeleteSets([snapshot.ds, readDeleteSet(updateDecoder)])
+  return equalDeleteSets(snapshot.ds, mergedDS)
+}
+
+/**
+ * @param {Snapshot} snapshot
+ * @param {Uint8Array} update
+ */
+export const snapshotContainsUpdate = (snapshot, update) => snapshotContainsUpdateV2(snapshot, update, UpdateDecoderV1)
--- a/src/utils/StructStore.js
+++ b/src/utils/StructStore.js
@ -1,4 +1,3 @@
-
 import {
  GC,
  splitItem,
@ -67,13 +66,13 @@ export const getState = (store, client) => {
 * @private
 * @function
 */
-export const integretyCheck = store => {
+export const integrityCheck = store => {
  store.clients.forEach(structs => {
    for (let i = 1; i < structs.length; i++) {
      const l = structs[i - 1]
      const r = structs[i]
      if (l.id.clock + l.length !== r.id.clock) {
-        throw new Error('StructStore failed integrety check')
+        throw new Error('StructStore failed integrity check')
      }
    }
  })
--- a/src/utils/Transaction.js
+++ b/src/utils/Transaction.js
@ -1,4 +1,3 @@
-
 import {
  getState,
  writeStructsFromTransaction,
@ -11,6 +10,7 @@ import {
  Item,
  generateNewClientId,
  createID,
+  cleanupYTextAfterTransaction,
  UpdateEncoderV1, UpdateEncoderV2, GC, StructStore, AbstractType, AbstractStruct, YEvent, Doc // eslint-disable-line
 } from '../internals.js'

@ -28,7 +28,8 @@ import { callAll } from 'lib0/function'
 * possible. Here is an example to illustrate the advantages of bundling:
 *
 * @example
- * const map = y.define('map', YMap)
+ * const ydoc = new Y.Doc()
+ * const map = ydoc.getMap('map')
 * // Log content when change is triggered
 * map.observe(() => {
 *   console.log('change triggered')
@ -37,7 +38,7 @@ import { callAll } from 'lib0/function'
 * 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(() => {
+ * ydoc.transact(() => {
 *   map.set('a', 1)
 *   map.set('b', 1)
 * }) // => "change triggered"
@ -114,6 +115,10 @@ export class Transaction {
     * @type {Set<Doc>}
     */
    this.subdocsLoaded = new Set()
+    /**
+     * @type {boolean}
+     */
+    this._needFormattingCleanup = false
  }
 }

@ -161,18 +166,29 @@ export const addChangedTypeToTransaction = (transaction, type, parentSub) => {
 /**
 * @param {Array<AbstractStruct>} structs
 * @param {number} pos
+ * @return {number} # of merged structs
 */
-const tryToMergeWithLeft = (structs, pos) => {
-  const left = structs[pos - 1]
-  const right = structs[pos]
-  if (left.deleted === right.deleted && left.constructor === right.constructor) {
-    if (left.mergeWith(right)) {
-      structs.splice(pos, 1)
-      if (right instanceof Item && right.parentSub !== null && /** @type {AbstractType<any>} */ (right.parent)._map.get(right.parentSub) === right) {
-        /** @type {AbstractType<any>} */ (right.parent)._map.set(right.parentSub, /** @type {Item} */ (left))
+const tryToMergeWithLefts = (structs, pos) => {
+  let right = structs[pos]
+  let left = structs[pos - 1]
+  let i = pos
+  for (; i > 0; right = left, left = structs[--i - 1]) {
+    if (left.deleted === right.deleted && left.constructor === right.constructor) {
+      if (left.mergeWith(right)) {
+        if (right instanceof Item && right.parentSub !== null && /** @type {AbstractType<any>} */ (right.parent)._map.get(right.parentSub) === right) {
+          /** @type {AbstractType<any>} */ (right.parent)._map.set(right.parentSub, /** @type {Item} */ (left))
+        }
+        continue
      }
    }
+    break
  }
+  const merged = pos - i
+  if (merged) {
+    // remove all merged structs from the array
+    structs.splice(pos + 1 - merged, merged)
+  }
+  return merged
 }

 /**
@ -209,7 +225,7 @@ const tryGcDeleteSet = (ds, store, gcFilter) => {
 */
 const tryMergeDeleteSet = (ds, store) => {
  // try to merge deleted / gc'd items
-  // merge from right to left for better efficiecy and so we don't miss any merge targets
+  // merge from right to left for better efficiency and so we don't miss any merge targets
  ds.clients.forEach((deleteItems, client) => {
    const structs = /** @type {Array<GC|Item>} */ (store.clients.get(client))
    for (let di = deleteItems.length - 1; di >= 0; di--) {
@ -219,9 +235,9 @@ const tryMergeDeleteSet = (ds, store) => {
      for (
        let si = mostRightIndexToCheck, struct = structs[si];
        si > 0 && struct.id.clock >= deleteItem.clock;
-        struct = structs[--si]
+        struct = structs[si]
      ) {
-        tryToMergeWithLeft(structs, si)
+        si -= 1 + tryToMergeWithLefts(structs, si)
      }
    }
  })
@ -270,31 +286,34 @@ const cleanupTransactions = (transactionCleanups, i) => {
      )
      fs.push(() => {
        // deep observe events
-        transaction.changedParentTypes.forEach((events, type) =>
-          fs.push(() => {
-            // We need to think about the possibility that the user transforms the
-            // Y.Doc in the event.
-            if (type._item === null || !type._item.deleted) {
-              events = events
-                .filter(event =>
-                  event.target._item === null || !event.target._item.deleted
-                )
-              events
-                .forEach(event => {
-                  event.currentTarget = type
-                })
-              // sort events by path length so that top-level events are fired first.
-              events
-                .sort((event1, event2) => event1.path.length - event2.path.length)
-              // We don't need to check for events.length
-              // because we know it has at least one element
-              callEventHandlerListeners(type._dEH, events, transaction)
-            }
-          })
-        )
-        fs.push(() => doc.emit('afterTransaction', [transaction, doc]))
+        transaction.changedParentTypes.forEach((events, type) => {
+          // We need to think about the possibility that the user transforms the
+          // Y.Doc in the event.
+          if (type._dEH.l.length > 0 && (type._item === null || !type._item.deleted)) {
+            events = events
+              .filter(event =>
+                event.target._item === null || !event.target._item.deleted
+              )
+            events
+              .forEach(event => {
+                event.currentTarget = type
+                // path is relative to the current target
+                event._path = null
+              })
+            // sort events by path length so that top-level events are fired first.
+            events
+              .sort((event1, event2) => event1.path.length - event2.path.length)
+            // We don't need to check for events.length
+            // because we know it has at least one element
+            callEventHandlerListeners(type._dEH, events, transaction)
+          }
+        })
      })
+      fs.push(() => doc.emit('afterTransaction', [transaction, doc]))
      callAll(fs, [])
+      if (transaction._needFormattingCleanup) {
+        cleanupYTextAfterTransaction(transaction)
+      }
    } finally {
      // Replace deleted items with ItemDeleted / GC.
      // This is where content is actually remove from the Yjs Doc.
@ -310,23 +329,25 @@ const cleanupTransactions = (transactionCleanups, i) => {
          const structs = /** @type {Array<GC|Item>} */ (store.clients.get(client))
          // we iterate from right to left so we can safely remove entries
          const firstChangePos = math.max(findIndexSS(structs, beforeClock), 1)
-          for (let i = structs.length - 1; i >= firstChangePos; i--) {
-            tryToMergeWithLeft(structs, i)
+          for (let i = structs.length - 1; i >= firstChangePos;) {
+            i -= 1 + tryToMergeWithLefts(structs, i)
          }
        }
      })
      // try to merge mergeStructs
      // @todo: it makes more sense to transform mergeStructs to a DS, sort it, and merge from right to left
      //        but at the moment DS does not handle duplicates
-      for (let i = 0; i < mergeStructs.length; i++) {
+      for (let i = mergeStructs.length - 1; i >= 0; i--) {
        const { client, clock } = mergeStructs[i].id
        const structs = /** @type {Array<GC|Item>} */ (store.clients.get(client))
        const replacedStructPos = findIndexSS(structs, clock)
        if (replacedStructPos + 1 < structs.length) {
-          tryToMergeWithLeft(structs, replacedStructPos + 1)
+          if (tryToMergeWithLefts(structs, replacedStructPos + 1) > 1) {
+            continue // no need to perform next check, both are already merged
+          }
        }
        if (replacedStructPos > 0) {
-          tryToMergeWithLeft(structs, replacedStructPos)
+          tryToMergeWithLefts(structs, replacedStructPos)
        }
      }
      if (!transaction.local && transaction.afterState.get(doc.clientID) !== transaction.beforeState.get(doc.clientID)) {
@ -376,15 +397,21 @@ const cleanupTransactions = (transactionCleanups, i) => {
 /**
 * Implements the functionality of `y.transact(()=>{..})`
 *
+ * @template T
 * @param {Doc} doc
- * @param {function(Transaction):void} f
+ * @param {function(Transaction):T} f
 * @param {any} [origin=true]
+ * @return {T}
 *
 * @function
 */
 export const transact = (doc, f, origin = null, local = true) => {
  const transactionCleanups = doc._transactionCleanups
  let initialCall = false
+  /**
+   * @type {any}
+   */
+  let result = null
  if (doc._transaction === null) {
    initialCall = true
    doc._transaction = new Transaction(doc, origin, local)
@ -395,7 +422,7 @@ export const transact = (doc, f, origin = null, local = true) => {
    doc.emit('beforeTransaction', [doc._transaction, doc])
  }
  try {
-    f(doc._transaction)
+    result = f(doc._transaction)
  } finally {
    if (initialCall) {
      const finishCleanup = doc._transaction === transactionCleanups[0]
@ -413,4 +440,5 @@ export const transact = (doc, f, origin = null, local = true) => {
      }
    }
  }
+  return result
 }
--- a/src/utils/UndoManager.js
+++ b/src/utils/UndoManager.js
@ -10,14 +10,15 @@ import {
  getItemCleanStart,
  isDeleted,
  addToDeleteSet,
-  Transaction, Doc, Item, GC, DeleteSet, AbstractType, YEvent // eslint-disable-line
+  YEvent, Transaction, Doc, Item, GC, DeleteSet, AbstractType // eslint-disable-line
 } from '../internals.js'

 import * as time from 'lib0/time'
 import * as array from 'lib0/array'
-import { Observable } from 'lib0/observable'
+import * as logging from 'lib0/logging'
+import { ObservableV2 } from 'lib0/observable'

-class StackItem {
+export class StackItem {
  /**
   * @param {DeleteSet} deletions
   * @param {DeleteSet} insertions
@ -38,7 +39,7 @@ class StackItem {
 */
 const clearUndoManagerStackItem = (tr, um, stackItem) => {
  iterateDeletedStructs(tr, stackItem.deletions, item => {
-    if (item instanceof Item && um.scope.some(type => isParentOf(type, item))) {
+    if (item instanceof Item && um.scope.some(type => type === tr.doc || isParentOf(/** @type {AbstractType<any>} */ (type), item))) {
      keepItem(item, false)
    }
  })
@ -47,15 +48,10 @@ const clearUndoManagerStackItem = (tr, um, stackItem) => {
 /**
 * @param {UndoManager} undoManager
 * @param {Array<StackItem>} stack
- * @param {string} eventType
+ * @param {'undo'|'redo'} eventType
 * @return {StackItem?}
 */
 const popStackItem = (undoManager, stack, eventType) => {
-  /**
-   * Whether a change happened
-   * @type {StackItem?}
-   */
-  let result = null
  /**
   * Keep a reference to the transaction so we can fire the event with the changedParentTypes
   * @type {any}
@ -64,7 +60,7 @@ const popStackItem = (undoManager, stack, eventType) => {
  const doc = undoManager.doc
  const scope = undoManager.scope
  transact(doc, transaction => {
-    while (stack.length > 0 && result === null) {
+    while (stack.length > 0 && undoManager.currStackItem === null) {
      const store = doc.store
      const stackItem = /** @type {StackItem} */ (stack.pop())
      /**
@ -85,7 +81,7 @@ const popStackItem = (undoManager, stack, eventType) => {
            }
            struct = item
          }
-          if (!struct.deleted && scope.some(type => isParentOf(type, /** @type {Item} */ (struct)))) {
+          if (!struct.deleted && scope.some(type => type === transaction.doc || isParentOf(/** @type {AbstractType<any>} */ (type), /** @type {Item} */ (struct)))) {
            itemsToDelete.push(struct)
          }
        }
@ -93,7 +89,7 @@ const popStackItem = (undoManager, stack, eventType) => {
      iterateDeletedStructs(transaction, stackItem.deletions, struct => {
        if (
          struct instanceof Item &&
-          scope.some(type => isParentOf(type, struct)) &&
+          scope.some(type => type === transaction.doc || isParentOf(/** @type {AbstractType<any>} */ (type), struct)) &&
          // Never redo structs in stackItem.insertions because they were created and deleted in the same capture interval.
          !isDeleted(stackItem.insertions, struct.id)
        ) {
@ -101,7 +97,7 @@ const popStackItem = (undoManager, stack, eventType) => {
        }
      })
      itemsToRedo.forEach(struct => {
-        performedChange = redoItem(transaction, struct, itemsToRedo, stackItem.insertions, undoManager.ignoreRemoteMapChanges) !== null || performedChange
+        performedChange = redoItem(transaction, struct, itemsToRedo, stackItem.insertions, undoManager.ignoreRemoteMapChanges, undoManager) !== null || performedChange
      })
      // We want to delete in reverse order so that children are deleted before
      // parents, so we have more information available when items are filtered.
@ -112,7 +108,7 @@ const popStackItem = (undoManager, stack, eventType) => {
          performedChange = true
        }
      }
-      result = performedChange ? stackItem : null
+      undoManager.currStackItem = performedChange ? stackItem : null
    }
    transaction.changed.forEach((subProps, type) => {
      // destroy search marker if necessary
@ -122,11 +118,13 @@ const popStackItem = (undoManager, stack, eventType) => {
    })
    _tr = transaction
  }, undoManager)
-  if (result != null) {
+  const res = undoManager.currStackItem
+  if (res != null) {
    const changedParentTypes = _tr.changedParentTypes
-    undoManager.emit('stack-item-popped', [{ stackItem: result, type: eventType, changedParentTypes }, undoManager])
+    undoManager.emit('stack-item-popped', [{ stackItem: res, type: eventType, changedParentTypes, origin: undoManager }, undoManager])
+    undoManager.currStackItem = null
  }
-  return result
+  return res
 }

 /**
@ -142,6 +140,14 @@ const popStackItem = (undoManager, stack, eventType) => {
 * @property {Doc} [doc] The document that this UndoManager operates on. Only needed if typeScope is empty.
 */

+/**
+ * @typedef {Object} StackItemEvent
+ * @property {StackItem} StackItemEvent.stackItem
+ * @property {any} StackItemEvent.origin
+ * @property {'undo'|'redo'} StackItemEvent.type
+ * @property {Map<AbstractType<YEvent<any>>,Array<YEvent<any>>>} StackItemEvent.changedParentTypes
+ */
+
 /**
 * Fires 'stack-item-added' event when a stack item was added to either the undo- or
 * the redo-stack. You may store additional stack information via the
@ -149,26 +155,27 @@ const popStackItem = (undoManager, stack, eventType) => {
 * Fires 'stack-item-popped' event when a stack item was popped from either the
 * undo- or the redo-stack. You may restore the saved stack information from `event.stackItem.meta`.
 *
- * @extends {Observable<'stack-item-added'|'stack-item-popped'|'stack-cleared'|'stack-item-updated'>}
+ * @extends {ObservableV2<{'stack-item-added':function(StackItemEvent, UndoManager):void, 'stack-item-popped': function(StackItemEvent, UndoManager):void, 'stack-cleared': function({ undoStackCleared: boolean, redoStackCleared: boolean }):void, 'stack-item-updated': function(StackItemEvent, UndoManager):void }>}
 */
-export class UndoManager extends Observable {
+export class UndoManager extends ObservableV2 {
  /**
-   * @param {AbstractType<any>|Array<AbstractType<any>>} typeScope Accepts either a single type, or an array of types
+   * @param {Doc|AbstractType<any>|Array<AbstractType<any>>} typeScope Limits the scope of the UndoManager. If this is set to a ydoc instance, all changes on that ydoc will be undone. If set to a specific type, only changes on that type or its children will be undone. Also accepts an array of types.
   * @param {UndoManagerOptions} options
   */
  constructor (typeScope, {
    captureTimeout = 500,
-    captureTransaction = tr => true,
+    captureTransaction = _tr => true,
    deleteFilter = () => true,
    trackedOrigins = new Set([null]),
    ignoreRemoteMapChanges = false,
-    doc = /** @type {Doc} */ (array.isArray(typeScope) ? typeScope[0].doc : typeScope.doc)
+    doc = /** @type {Doc} */ (array.isArray(typeScope) ? typeScope[0].doc : typeScope instanceof Doc ? typeScope : typeScope.doc)
  } = {}) {
    super()
    /**
-     * @type {Array<AbstractType<any>>}
+     * @type {Array<AbstractType<any> | Doc>}
     */
    this.scope = []
+    this.doc = doc
    this.addToScope(typeScope)
    this.deleteFilter = deleteFilter
    trackedOrigins.add(this)
@ -189,7 +196,12 @@ export class UndoManager extends Observable {
     */
    this.undoing = false
    this.redoing = false
-    this.doc = doc
+    /**
+     * The currently popped stack item if UndoManager.undoing or UndoManager.redoing
+     *
+     * @type {StackItem|null}
+     */
+    this.currStackItem = null
    this.lastChange = 0
    this.ignoreRemoteMapChanges = ignoreRemoteMapChanges
    this.captureTimeout = captureTimeout
@ -200,7 +212,7 @@ export class UndoManager extends Observable {
      // Only track certain transactions
      if (
        !this.captureTransaction(transaction) ||
-        !this.scope.some(type => transaction.changedParentTypes.has(type)) ||
+        !this.scope.some(type => transaction.changedParentTypes.has(/** @type {AbstractType<any>} */ (type)) || type === this.doc) ||
        (!this.trackedOrigins.has(transaction.origin) && (!transaction.origin || !this.trackedOrigins.has(transaction.origin.constructor)))
      ) {
        return
@ -239,10 +251,13 @@ export class UndoManager extends Observable {
      }
      // make sure that deleted structs are not gc'd
      iterateDeletedStructs(transaction, transaction.deleteSet, /** @param {Item|GC} item */ item => {
-        if (item instanceof Item && this.scope.some(type => isParentOf(type, item))) {
+        if (item instanceof Item && this.scope.some(type => type === transaction.doc || isParentOf(/** @type {AbstractType<any>} */ (type), item))) {
          keepItem(item, true)
        }
      })
+      /**
+       * @type {[StackItemEvent, UndoManager]}
+       */
      const changeEvent = [{ stackItem: stack[stack.length - 1], origin: transaction.origin, type: undoing ? 'redo' : 'undo', changedParentTypes: transaction.changedParentTypes }, this]
      if (didAdd) {
        this.emit('stack-item-added', changeEvent)
@ -257,12 +272,17 @@ export class UndoManager extends Observable {
  }

  /**
-   * @param {Array<AbstractType<any>> | AbstractType<any>} ytypes
+   * Extend the scope.
+   *
+   * @param {Array<AbstractType<any> | Doc> | AbstractType<any> | Doc} ytypes
   */
  addToScope (ytypes) {
+    const tmpSet = new Set(this.scope)
    ytypes = array.isArray(ytypes) ? ytypes : [ytypes]
    ytypes.forEach(ytype => {
-      if (this.scope.every(yt => yt !== ytype)) {
+      if (!tmpSet.has(ytype)) {
+        tmpSet.add(ytype)
+        if (ytype instanceof AbstractType ? ytype.doc !== this.doc : ytype !== this.doc) logging.warn('[yjs#509] Not same Y.Doc') // use MultiDocUndoManager instead. also see https://github.com/yjs/yjs/issues/509
        this.scope.push(ytype)
      }
    })
--- a/src/utils/UpdateEncoder.js
+++ b/src/utils/UpdateEncoder.js
@ -1,4 +1,3 @@
-
 import * as error from 'lib0/error'
 import * as encoding from 'lib0/encoding'

@ -168,7 +167,7 @@ export class UpdateEncoderV2 extends DSEncoderV2 {
     */
    this.keyMap = new Map()
    /**
-     * Refers to the next uniqe key-identifier to me used.
+     * Refers to the next unique key-identifier to me used.
     * See writeKey method for more information.
     *
     * @type {number}
--- a/src/utils/YEvent.js
+++ b/src/utils/YEvent.js
@ -1,4 +1,3 @@
-
 import {
  isDeleted,
  Item, AbstractType, Transaction, AbstractStruct // eslint-disable-line
@ -6,6 +5,9 @@ import {

 import * as set from 'lib0/set'
 import * as array from 'lib0/array'
+import * as error from 'lib0/error'
+
+const errorComputeChanges = 'You must not compute changes after the event-handler fired.'

 /**
 * @template {AbstractType<any>} T
@ -44,6 +46,10 @@ export class YEvent {
     * @type {null | Array<{ insert?: string | Array<any> | object | AbstractType<any>, retain?: number, delete?: number, attributes?: Object<string, any> }>}
     */
    this._delta = null
+    /**
+     * @type {Array<string|number>|null}
+     */
+    this._path = null
  }

  /**
@ -60,8 +66,7 @@ export class YEvent {
   *   type === event.target // => true
   */
  get path () {
-    // @ts-ignore _item is defined because target is integrated
-    return getPathTo(this.currentTarget, this.target)
+    return this._path || (this._path = getPathTo(this.currentTarget, this.target))
  }

  /**
@ -81,6 +86,9 @@ export class YEvent {
   */
  get keys () {
    if (this._keys === null) {
+      if (this.transaction.doc._transactionCleanups.length === 0) {
+        throw error.create(errorComputeChanges)
+      }
      const keys = new Map()
      const target = this.target
      const changed = /** @type Set<string|null> */ (this.transaction.changed.get(target))
@ -130,6 +138,11 @@ export class YEvent {
  }

  /**
+   * This is a computed property. Note that this can only be safely computed during the
+   * event call. Computing this property after other changes happened might result in
+   * unexpected behavior (incorrect computation of deltas). A safe way to collect changes
+   * is to store the `changes` or the `delta` object. Avoid storing the `transaction` object.
+   *
   * @type {Array<{insert?: string | Array<any> | object | AbstractType<any>, retain?: number, delete?: number, attributes?: Object<string, any>}>}
   */
  get delta () {
@ -149,11 +162,19 @@ export class YEvent {
  }

  /**
+   * This is a computed property. Note that this can only be safely computed during the
+   * event call. Computing this property after other changes happened might result in
+   * unexpected behavior (incorrect computation of deltas). A safe way to collect changes
+   * is to store the `changes` or the `delta` object. Avoid storing the `transaction` object.
+   *
   * @type {{added:Set<Item>,deleted:Set<Item>,keys:Map<string,{action:'add'|'update'|'delete',oldValue:any}>,delta:Array<{insert?:Array<any>|string, delete?:number, retain?:number}>}}
   */
  get changes () {
    let changes = this._changes
    if (changes === null) {
+      if (this.transaction.doc._transactionCleanups.length === 0) {
+        throw error.create(errorComputeChanges)
+      }
      const target = this.target
      const added = set.create()
      const deleted = set.create()
@ -243,8 +264,8 @@ const getPathTo = (parent, child) => {
      let i = 0
      let c = /** @type {AbstractType<any>} */ (child._item.parent)._start
      while (c !== child._item && c !== null) {
-        if (!c.deleted) {
-          i++
+        if (!c.deleted && c.countable) {
+          i += c.length
        }
        c = c.right
      }
--- a/src/utils/encoding.js
+++ b/src/utils/encoding.js
@ -1,4 +1,3 @@
-
 /**
 * @module encoding
 */
@ -45,6 +44,7 @@ import * as decoding from 'lib0/decoding'
 import * as binary from 'lib0/binary'
 import * as map from 'lib0/map'
 import * as math from 'lib0/math'
+import * as array from 'lib0/array'

 /**
 * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
@ -87,7 +87,7 @@ export const writeClientsStructs = (encoder, store, _sm) => {
      sm.set(client, clock)
    }
  })
-  getStateVector(store).forEach((clock, client) => {
+  getStateVector(store).forEach((_clock, client) => {
    if (!_sm.has(client)) {
      sm.set(client, 0)
    }
@ -96,9 +96,8 @@ export const writeClientsStructs = (encoder, store, _sm) => {
  encoding.writeVarUint(encoder.restEncoder, sm.size)
  // Write items with higher client ids first
  // This heavily improves the conflict algorithm.
-  Array.from(sm.entries()).sort((a, b) => b[0] - a[0]).forEach(([client, clock]) => {
-    // @ts-ignore
-    writeStructs(encoder, store.clients.get(client), client, clock)
+  array.from(sm.entries()).sort((a, b) => b[0] - a[0]).forEach(([client, clock]) => {
+    writeStructs(encoder, /** @type {Array<GC|Item>} */ (store.clients.get(client)), client, clock)
  })
 }

@ -155,7 +154,7 @@ export const readClientsStructRefs = (decoder, doc) => {
          // @type {string|null}
          const struct = new Item(
            createID(client, clock),
-            null, // leftd
+            null, // left
            (info & binary.BIT8) === binary.BIT8 ? decoder.readLeftID() : null, // origin
            null, // right
            (info & binary.BIT7) === binary.BIT7 ? decoder.readRightID() : null, // right origin
@ -179,7 +178,7 @@ export const readClientsStructRefs = (decoder, doc) => {

          const struct = new Item(
            createID(client, clock),
-            null, // leftd
+            null, // left
            origin, // origin
            null, // right
            rightOrigin, // right origin
@ -212,7 +211,7 @@ export const readClientsStructRefs = (decoder, doc) => {
 * then we start emptying the stack.
 *
 * It is not possible to have circles: i.e. struct1 (from client1) depends on struct2 (from client2)
- * depends on struct3 (from client1). Therefore the max stack size is eqaul to `structReaders.length`.
+ * depends on struct3 (from client1). Therefore the max stack size is equal to `structReaders.length`.
 *
 * This method is implemented in a way so that we can resume computation if this update
 * causally depends on another update.
@ -231,7 +230,7 @@ const integrateStructs = (transaction, store, clientsStructRefs) => {
   */
  const stack = []
  // sort them so that we take the higher id first, in case of conflicts the lower id will probably not conflict with the id from the higher user.
-  let clientsStructRefsIds = Array.from(clientsStructRefs.keys()).sort((a, b) => a - b)
+  let clientsStructRefsIds = array.from(clientsStructRefs.keys()).sort((a, b) => a - b)
  if (clientsStructRefsIds.length === 0) {
    return null
  }
@ -251,7 +250,7 @@ const integrateStructs = (transaction, store, clientsStructRefs) => {
    return nextStructsTarget
  }
  let curStructsTarget = getNextStructTarget()
-  if (curStructsTarget === null && stack.length === 0) {
+  if (curStructsTarget === null) {
    return null
  }

@ -280,14 +279,14 @@ const integrateStructs = (transaction, store, clientsStructRefs) => {
  const addStackToRestSS = () => {
    for (const item of stack) {
      const client = item.id.client
-      const unapplicableItems = clientsStructRefs.get(client)
-      if (unapplicableItems) {
+      const inapplicableItems = clientsStructRefs.get(client)
+      if (inapplicableItems) {
        // decrement because we weren't able to apply previous operation
-        unapplicableItems.i--
-        restStructs.clients.set(client, unapplicableItems.refs.slice(unapplicableItems.i))
+        inapplicableItems.i--
+        restStructs.clients.set(client, inapplicableItems.refs.slice(inapplicableItems.i))
        clientsStructRefs.delete(client)
-        unapplicableItems.i = 0
-        unapplicableItems.refs = []
+        inapplicableItems.i = 0
+        inapplicableItems.refs = []
      } else {
        // item was the last item on clientsStructRefs and the field was already cleared. Add item to restStructs and continue
        restStructs.clients.set(client, [item])
@ -371,7 +370,7 @@ export const writeStructsFromTransaction = (encoder, transaction) => writeClient
 /**
 * Read and apply a document update.
 *
- * This function has the same effect as `applyUpdate` but accepts an decoder.
+ * This function has the same effect as `applyUpdate` but accepts a decoder.
 *
 * @param {decoding.Decoder} decoder
 * @param {Doc} ydoc
@ -452,7 +451,7 @@ export const readUpdateV2 = (decoder, ydoc, transactionOrigin, structDecoder = n
 /**
 * Read and apply a document update.
 *
- * This function has the same effect as `applyUpdate` but accepts an decoder.
+ * This function has the same effect as `applyUpdate` but accepts a decoder.
 *
 * @param {decoding.Decoder} decoder
 * @param {Doc} ydoc
@ -601,7 +600,7 @@ export const decodeStateVector = decodedState => readStateVector(new DSDecoderV1
 */
 export const writeStateVector = (encoder, sv) => {
  encoding.writeVarUint(encoder.restEncoder, sv.size)
-  Array.from(sv.entries()).sort((a, b) => b[0] - a[0]).forEach(([client, clock]) => {
+  array.from(sv.entries()).sort((a, b) => b[0] - a[0]).forEach(([client, clock]) => {
    encoding.writeVarUint(encoder.restEncoder, client) // @todo use a special client decoder that is based on mapping
    encoding.writeVarUint(encoder.restEncoder, clock)
  })
--- a/src/utils/isParentOf.js
+++ b/src/utils/isParentOf.js
@ -1,4 +1,3 @@
-
 import { AbstractType, Item } from '../internals.js' // eslint-disable-line

 /**
--- a/src/utils/logging.js
+++ b/src/utils/logging.js
@ -1,4 +1,3 @@
-
 import {
  AbstractType // eslint-disable-line
 } from '../internals.js'
--- a/src/utils/updates.js
+++ b/src/utils/updates.js
@ -1,20 +1,40 @@
-
 import * as binary from 'lib0/binary'
 import * as decoding from 'lib0/decoding'
 import * as encoding from 'lib0/encoding'
+import * as error from 'lib0/error'
+import * as f from 'lib0/function'
 import * as logging from 'lib0/logging'
+import * as map from 'lib0/map'
 import * as math from 'lib0/math'
+import * as string from 'lib0/string'
+
 import {
+  ContentAny,
+  ContentBinary,
+  ContentDeleted,
+  ContentDoc,
+  ContentEmbed,
+  ContentFormat,
+  ContentJSON,
+  ContentString,
+  ContentType,
  createID,
-  readItemContent,
-  readDeleteSet,
-  writeDeleteSet,
-  Skip,
-  mergeDeleteSets,
+  decodeStateVector,
  DSEncoderV1,
  DSEncoderV2,
-  decodeStateVector,
-  Item, GC, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2 // eslint-disable-line
+  GC,
+  Item,
+  mergeDeleteSets,
+  readDeleteSet,
+  readItemContent,
+  Skip,
+  UpdateDecoderV1,
+  UpdateDecoderV2,
+  UpdateEncoderV1,
+  UpdateEncoderV2,
+  writeDeleteSet,
+  YXmlElement,
+  YXmlHook
 } from '../internals.js'

 /**
@ -552,17 +572,17 @@ const finishLazyStructWriting = (lazyWriter) => {

 /**
 * @param {Uint8Array} update
+ * @param {function(Item|GC|Skip):Item|GC|Skip} blockTransformer
 * @param {typeof UpdateDecoderV2 | typeof UpdateDecoderV1} YDecoder
 * @param {typeof UpdateEncoderV2 | typeof UpdateEncoderV1 } YEncoder
 */
-export const convertUpdateFormat = (update, YDecoder, YEncoder) => {
+export const convertUpdateFormat = (update, blockTransformer, YDecoder, YEncoder) => {
  const updateDecoder = new YDecoder(decoding.createDecoder(update))
  const lazyDecoder = new LazyStructReader(updateDecoder, false)
  const updateEncoder = new YEncoder()
  const lazyWriter = new LazyStructWriter(updateEncoder)
-
  for (let curr = lazyDecoder.curr; curr !== null; curr = lazyDecoder.next()) {
-    writeStructToLazyStructWriter(lazyWriter, curr, 0)
+    writeStructToLazyStructWriter(lazyWriter, blockTransformer(curr), 0)
  }
  finishLazyStructWriting(lazyWriter)
  const ds = readDeleteSet(updateDecoder)
@ -571,11 +591,132 @@ export const convertUpdateFormat = (update, YDecoder, YEncoder) => {
 }

 /**
- * @param {Uint8Array} update
+ * @typedef {Object} ObfuscatorOptions
+ * @property {boolean} [ObfuscatorOptions.formatting=true]
+ * @property {boolean} [ObfuscatorOptions.subdocs=true]
+ * @property {boolean} [ObfuscatorOptions.yxml=true] Whether to obfuscate nodeName / hookName
 */
-export const convertUpdateFormatV1ToV2 = update => convertUpdateFormat(update, UpdateDecoderV1, UpdateEncoderV2)
+
+/**
+ * @param {ObfuscatorOptions} obfuscator
+ */
+const createObfuscator = ({ formatting = true, subdocs = true, yxml = true } = {}) => {
+  let i = 0
+  const mapKeyCache = map.create()
+  const nodeNameCache = map.create()
+  const formattingKeyCache = map.create()
+  const formattingValueCache = map.create()
+  formattingValueCache.set(null, null) // end of a formatting range should always be the end of a formatting range
+  /**
+   * @param {Item|GC|Skip} block
+   * @return {Item|GC|Skip}
+   */
+  return block => {
+    switch (block.constructor) {
+      case GC:
+      case Skip:
+        return block
+      case Item: {
+        const item = /** @type {Item} */ (block)
+        const content = item.content
+        switch (content.constructor) {
+          case ContentDeleted:
+            break
+          case ContentType: {
+            if (yxml) {
+              const type = /** @type {ContentType} */ (content).type
+              if (type instanceof YXmlElement) {
+                type.nodeName = map.setIfUndefined(nodeNameCache, type.nodeName, () => 'node-' + i)
+              }
+              if (type instanceof YXmlHook) {
+                type.hookName = map.setIfUndefined(nodeNameCache, type.hookName, () => 'hook-' + i)
+              }
+            }
+            break
+          }
+          case ContentAny: {
+            const c = /** @type {ContentAny} */ (content)
+            c.arr = c.arr.map(() => i)
+            break
+          }
+          case ContentBinary: {
+            const c = /** @type {ContentBinary} */ (content)
+            c.content = new Uint8Array([i])
+            break
+          }
+          case ContentDoc: {
+            const c = /** @type {ContentDoc} */ (content)
+            if (subdocs) {
+              c.opts = {}
+              c.doc.guid = i + ''
+            }
+            break
+          }
+          case ContentEmbed: {
+            const c = /** @type {ContentEmbed} */ (content)
+            c.embed = {}
+            break
+          }
+          case ContentFormat: {
+            const c = /** @type {ContentFormat} */ (content)
+            if (formatting) {
+              c.key = map.setIfUndefined(formattingKeyCache, c.key, () => i + '')
+              c.value = map.setIfUndefined(formattingValueCache, c.value, () => ({ i }))
+            }
+            break
+          }
+          case ContentJSON: {
+            const c = /** @type {ContentJSON} */ (content)
+            c.arr = c.arr.map(() => i)
+            break
+          }
+          case ContentString: {
+            const c = /** @type {ContentString} */ (content)
+            c.str = string.repeat((i % 10) + '', c.str.length)
+            break
+          }
+          default:
+            // unknown content type
+            error.unexpectedCase()
+        }
+        if (item.parentSub) {
+          item.parentSub = map.setIfUndefined(mapKeyCache, item.parentSub, () => i + '')
+        }
+        i++
+        return block
+      }
+      default:
+        // unknown block-type
+        error.unexpectedCase()
+    }
+  }
+}
+
+/**
+ * This function obfuscates the content of a Yjs update. This is useful to share
+ * buggy Yjs documents while significantly limiting the possibility that a
+ * developer can on the user. Note that it might still be possible to deduce
+ * some information by analyzing the "structure" of the document or by analyzing
+ * the typing behavior using the CRDT-related metadata that is still kept fully
+ * intact.
+ *
+ * @param {Uint8Array} update
+ * @param {ObfuscatorOptions} [opts]
+ */
+export const obfuscateUpdate = (update, opts) => convertUpdateFormat(update, createObfuscator(opts), UpdateDecoderV1, UpdateEncoderV1)
+
+/**
+ * @param {Uint8Array} update
+ * @param {ObfuscatorOptions} [opts]
+ */
+export const obfuscateUpdateV2 = (update, opts) => convertUpdateFormat(update, createObfuscator(opts), UpdateDecoderV2, UpdateEncoderV2)

 /**
 * @param {Uint8Array} update
 */
-export const convertUpdateFormatV2ToV1 = update => convertUpdateFormat(update, UpdateDecoderV2, UpdateEncoderV1)
+export const convertUpdateFormatV1ToV2 = update => convertUpdateFormat(update, f.id, UpdateDecoderV1, UpdateEncoderV2)
+
+/**
+ * @param {Uint8Array} update
+ */
+export const convertUpdateFormatV2ToV1 = update => convertUpdateFormat(update, f.id, UpdateDecoderV2, UpdateEncoderV1)
--- a/tests/compatibility.tests.js
+++ b/tests/compatibility.tests.js
@ -1,6 +1,5 @@
-
 /**
- * Testing if encoding/decoding compatibility and integration compatiblity is given.
+ * Testing if encoding/decoding compatibility and integration compatibility is given.
 * We expect that the document always looks the same, even if we upgrade the integration algorithm, or add additional encoding approaches.
 *
 * The v1 documents were generated with Yjs v13.2.0 based on the randomisized tests.
--- a/tests/doc.tests.js
+++ b/tests/doc.tests.js
@ -1,7 +1,24 @@
-
 import * as Y from '../src/index.js'
 import * as t from 'lib0/testing'

+/**
+ * @param {t.TestCase} _tc
+ */
+export const testAfterTransactionRecursion = _tc => {
+  const ydoc = new Y.Doc()
+  const yxml = ydoc.getXmlFragment('')
+  ydoc.on('afterTransaction', tr => {
+    if (tr.origin === 'test') {
+      yxml.toJSON()
+    }
+  })
+  ydoc.transact(_tr => {
+    for (let i = 0; i < 15000; i++) {
+      yxml.push([new Y.XmlText('a')])
+    }
+  }, 'test')
+}
+
 /**
 * @param {t.TestCase} _tc
 */
@ -15,7 +32,7 @@ export const testOriginInTransaction = _tc => {
  doc.on('afterTransaction', (tr) => {
    origins.push(tr.origin)
    if (origins.length <= 1) {
-      ytext.toDelta()
+      ytext.toDelta(Y.snapshot(doc)) // adding a snapshot forces toDelta to create a cleanup transaction
      doc.transact(() => {
        ytext.insert(0, 'a')
      }, 'nested')
@ -30,9 +47,9 @@ export const testOriginInTransaction = _tc => {
 /**
 * Client id should be changed when an instance receives updates from another client using the same client id.
 *
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testClientIdDuplicateChange = tc => {
+export const testClientIdDuplicateChange = _tc => {
  const doc1 = new Y.Doc()
  doc1.clientID = 0
  const doc2 = new Y.Doc()
@ -44,9 +61,9 @@ export const testClientIdDuplicateChange = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testGetTypeEmptyId = tc => {
+export const testGetTypeEmptyId = _tc => {
  const doc1 = new Y.Doc()
  doc1.getText('').insert(0, 'h')
  doc1.getText().insert(1, 'i')
@ -57,9 +74,9 @@ export const testGetTypeEmptyId = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testToJSON = tc => {
+export const testToJSON = _tc => {
  const doc = new Y.Doc()
  t.compare(doc.toJSON(), {}, 'doc.toJSON yields empty object')

@ -84,9 +101,9 @@ export const testToJSON = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testSubdoc = tc => {
+export const testSubdoc = _tc => {
  const doc = new Y.Doc()
  doc.load() // doesn't do anything
  {
@ -151,9 +168,9 @@ export const testSubdoc = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testSubdocLoadEdgeCases = tc => {
+export const testSubdocLoadEdgeCases = _tc => {
  const ydoc = new Y.Doc()
  const yarray = ydoc.getArray()
  const subdoc1 = new Y.Doc()
@ -198,9 +215,9 @@ export const testSubdocLoadEdgeCases = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testSubdocLoadEdgeCasesAutoload = tc => {
+export const testSubdocLoadEdgeCasesAutoload = _tc => {
  const ydoc = new Y.Doc()
  const yarray = ydoc.getArray()
  const subdoc1 = new Y.Doc({ autoLoad: true })
@ -240,9 +257,9 @@ export const testSubdocLoadEdgeCasesAutoload = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testSubdocsUndo = tc => {
+export const testSubdocsUndo = _tc => {
  const ydoc = new Y.Doc()
  const elems = ydoc.getXmlFragment()
  const undoManager = new Y.UndoManager(elems)
@ -255,9 +272,9 @@ export const testSubdocsUndo = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testLoadDocs = async tc => {
+export const testLoadDocsEvent = async _tc => {
  const ydoc = new Y.Doc()
  t.assert(ydoc.isLoaded === false)
  let loadedEvent = false
@ -269,3 +286,44 @@ export const testLoadDocs = async tc => {
  t.assert(loadedEvent)
  t.assert(ydoc.isLoaded)
 }
+
+/**
+ * @param {t.TestCase} _tc
+ */
+export const testSyncDocsEvent = async _tc => {
+  const ydoc = new Y.Doc()
+  t.assert(ydoc.isLoaded === false)
+  t.assert(ydoc.isSynced === false)
+  let loadedEvent = false
+  ydoc.once('load', () => {
+    loadedEvent = true
+  })
+  let syncedEvent = false
+  ydoc.once('sync', /** @param {any} isSynced */ (isSynced) => {
+    syncedEvent = true
+    t.assert(isSynced)
+  })
+  ydoc.emit('sync', [true, ydoc])
+  await ydoc.whenLoaded
+  const oldWhenSynced = ydoc.whenSynced
+  await ydoc.whenSynced
+  t.assert(loadedEvent)
+  t.assert(syncedEvent)
+  t.assert(ydoc.isLoaded)
+  t.assert(ydoc.isSynced)
+  let loadedEvent2 = false
+  ydoc.on('load', () => {
+    loadedEvent2 = true
+  })
+  let syncedEvent2 = false
+  ydoc.on('sync', (isSynced) => {
+    syncedEvent2 = true
+    t.assert(isSynced === false)
+  })
+  ydoc.emit('sync', [false, ydoc])
+  t.assert(!loadedEvent2)
+  t.assert(syncedEvent2)
+  t.assert(ydoc.isLoaded)
+  t.assert(!ydoc.isSynced)
+  t.assert(ydoc.whenSynced !== oldWhenSynced)
+}
--- a/tests/index.js
+++ b/tests/index.js
@ -1,3 +1,4 @@
+/* eslint-env node */

 import * as map from './y-map.tests.js'
 import * as array from './y-array.tests.js'
@ -14,15 +15,28 @@ import * as relativePositions from './relativePositions.tests.js'
 import { runTests } from 'lib0/testing'
 import { isBrowser, isNode } from 'lib0/environment'
 import * as log from 'lib0/logging'
+import { environment } from 'lib0'

 if (isBrowser) {
  log.createVConsole(document.body)
 }
-runTests({
+
+/**
+ * @type {any}
+ */
+const tests = {
  doc, map, array, text, xml, encoding, undoredo, compatibility, snapshot, updates, relativePositions
-}).then(success => {
+}
+
+const run = async () => {
+  if (environment.isNode) {
+    // tests.nodejs = await import('./node.tests.js')
+  }
+
+  const success = await runTests(tests)
  /* istanbul ignore next */
  if (isNode) {
    process.exit(success ? 0 : 1)
  }
-})
+}
+run()
--- a/tests/relativePositions.tests.js
+++ b/tests/relativePositions.tests.js
@ -1,4 +1,3 @@
-
 import * as Y from '../src/index.js'
 import * as t from 'lib0/testing'

@ -86,6 +85,26 @@ export const testRelativePositionCase6 = tc => {
  checkRelativePositions(ytext)
 }

+/**
+ * Testing https://github.com/yjs/yjs/issues/657
+ *
+ * @param {t.TestCase} tc
+ */
+export const testRelativePositionCase7 = tc => {
+  const docA = new Y.Doc()
+  const textA = docA.getText('text')
+  textA.insert(0, 'abcde')
+  // Create a relative position at index 2 in 'textA'
+  const relativePosition = Y.createRelativePositionFromTypeIndex(textA, 2)
+  // Verify that the absolutes positions on 'docA' are the same
+  const absolutePositionWithFollow =
+    Y.createAbsolutePositionFromRelativePosition(relativePosition, docA, true)
+  const absolutePositionWithoutFollow =
+    Y.createAbsolutePositionFromRelativePosition(relativePosition, docA, false)
+  t.assert(absolutePositionWithFollow?.index === 2)
+  t.assert(absolutePositionWithoutFollow?.index === 2)
+}
+
 /**
 * @param {t.TestCase} tc
 */
@ -102,3 +121,25 @@ export const testRelativePositionAssociationDifference = tc => {
  t.assert(posRight != null && posRight.index === 2)
  t.assert(posLeft != null && posLeft.index === 1)
 }
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testRelativePositionWithUndo = tc => {
+  const ydoc = new Y.Doc()
+  const ytext = ydoc.getText()
+  ytext.insert(0, 'hello world')
+  const rpos = Y.createRelativePositionFromTypeIndex(ytext, 1)
+  const um = new Y.UndoManager(ytext)
+  ytext.delete(0, 6)
+  t.assert(Y.createAbsolutePositionFromRelativePosition(rpos, ydoc)?.index === 0)
+  um.undo()
+  t.assert(Y.createAbsolutePositionFromRelativePosition(rpos, ydoc)?.index === 1)
+  const posWithoutFollow = Y.createAbsolutePositionFromRelativePosition(rpos, ydoc, false)
+  console.log({ posWithoutFollow })
+  t.assert(Y.createAbsolutePositionFromRelativePosition(rpos, ydoc, false)?.index === 6)
+  const ydocClone = new Y.Doc()
+  Y.applyUpdate(ydocClone, Y.encodeStateAsUpdate(ydoc))
+  t.assert(Y.createAbsolutePositionFromRelativePosition(rpos, ydocClone)?.index === 6)
+  t.assert(Y.createAbsolutePositionFromRelativePosition(rpos, ydocClone, false)?.index === 6)
+}
--- a/tests/snapshot.tests.js
+++ b/tests/snapshot.tests.js
@ -3,9 +3,36 @@ import * as t from 'lib0/testing'
 import { init } from './testHelper.js'

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testBasicRestoreSnapshot = tc => {
+export const testBasic = _tc => {
+  const ydoc = new Y.Doc({ gc: false })
+  ydoc.getText().insert(0, 'world!')
+  const snapshot = Y.snapshot(ydoc)
+  ydoc.getText().insert(0, 'hello ')
+  const restored = Y.createDocFromSnapshot(ydoc, snapshot)
+  t.assert(restored.getText().toString() === 'world!')
+}
+
+/**
+ * @param {t.TestCase} _tc
+ */
+export const testBasicXmlAttributes = _tc => {
+  const ydoc = new Y.Doc({ gc: false })
+  const yxml = ydoc.getMap().set('el', new Y.XmlElement('div'))
+  const snapshot1 = Y.snapshot(ydoc)
+  yxml.setAttribute('a', '1')
+  const snapshot2 = Y.snapshot(ydoc)
+  yxml.setAttribute('a', '2')
+  t.compare(yxml.getAttributes(), { a: '2' })
+  t.compare(yxml.getAttributes(snapshot2), { a: '1' })
+  t.compare(yxml.getAttributes(snapshot1), {})
+}
+
+/**
+ * @param {t.TestCase} _tc
+ */
+export const testBasicRestoreSnapshot = _tc => {
  const doc = new Y.Doc({ gc: false })
  doc.getArray('array').insert(0, ['hello'])
  const snap = Y.snapshot(doc)
@ -18,9 +45,9 @@ export const testBasicRestoreSnapshot = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testEmptyRestoreSnapshot = tc => {
+export const testEmptyRestoreSnapshot = _tc => {
  const doc = new Y.Doc({ gc: false })
  const snap = Y.snapshot(doc)
  snap.sv.set(9999, 0)
@ -31,16 +58,16 @@ export const testEmptyRestoreSnapshot = tc => {
  t.compare(docRestored.getArray().toArray(), [])
  t.compare(doc.getArray().toArray(), ['world'])

-  // now this snapshot reflects the latest state. It shoult still work.
+  // now this snapshot reflects the latest state. It should still work.
  const snap2 = Y.snapshot(doc)
  const docRestored2 = Y.createDocFromSnapshot(doc, snap2)
  t.compare(docRestored2.getArray().toArray(), ['world'])
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testRestoreSnapshotWithSubType = tc => {
+export const testRestoreSnapshotWithSubType = _tc => {
  const doc = new Y.Doc({ gc: false })
  doc.getArray('array').insert(0, [new Y.Map()])
  const subMap = doc.getArray('array').get(0)
@ -61,9 +88,9 @@ export const testRestoreSnapshotWithSubType = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testRestoreDeletedItem1 = tc => {
+export const testRestoreDeletedItem1 = _tc => {
  const doc = new Y.Doc({ gc: false })
  doc.getArray('array').insert(0, ['item1', 'item2'])

@ -77,9 +104,9 @@ export const testRestoreDeletedItem1 = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testRestoreLeftItem = tc => {
+export const testRestoreLeftItem = _tc => {
  const doc = new Y.Doc({ gc: false })
  doc.getArray('array').insert(0, ['item1'])
  doc.getMap('map').set('test', 1)
@ -95,9 +122,9 @@ export const testRestoreLeftItem = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testDeletedItemsBase = tc => {
+export const testDeletedItemsBase = _tc => {
  const doc = new Y.Doc({ gc: false })
  doc.getArray('array').insert(0, ['item1'])
  doc.getArray('array').delete(0)
@ -111,9 +138,9 @@ export const testDeletedItemsBase = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testDeletedItems2 = tc => {
+export const testDeletedItems2 = _tc => {
  const doc = new Y.Doc({ gc: false })
  doc.getArray('array').insert(0, ['item1', 'item2', 'item3'])
  doc.getArray('array').delete(1)
@ -169,3 +196,28 @@ export const testDependentChanges = tc => {
  const docRestored1 = Y.createDocFromSnapshot(array1.doc, snap)
  t.compare(docRestored1.getArray('array').toArray(), ['user1item1', 'user2item1'])
 }
+
+/**
+ * @param {t.TestCase} _tc
+ */
+export const testContainsUpdate = _tc => {
+  const ydoc = new Y.Doc()
+  /**
+   * @type {Array<Uint8Array>}
+   */
+  const updates = []
+  ydoc.on('update', update => {
+    updates.push(update)
+  })
+  const yarr = ydoc.getArray()
+  const snapshot1 = Y.snapshot(ydoc)
+  yarr.insert(0, [1])
+  const snapshot2 = Y.snapshot(ydoc)
+  yarr.delete(0, 1)
+  const snapshotFinal = Y.snapshot(ydoc)
+  t.assert(!Y.snapshotContainsUpdate(snapshot1, updates[0]))
+  t.assert(!Y.snapshotContainsUpdate(snapshot2, updates[1]))
+  t.assert(Y.snapshotContainsUpdate(snapshot2, updates[0]))
+  t.assert(Y.snapshotContainsUpdate(snapshotFinal, updates[0]))
+  t.assert(Y.snapshotContainsUpdate(snapshotFinal, updates[1]))
+}
--- a/tests/testHelper.js
+++ b/tests/testHelper.js
@ -1,4 +1,3 @@
-
 import * as t from 'lib0/testing'
 import * as prng from 'lib0/prng'
 import * as encoding from 'lib0/encoding'
@ -35,7 +34,7 @@ export const encV1 = {
  mergeUpdates: Y.mergeUpdates,
  applyUpdate: Y.applyUpdate,
  logUpdate: Y.logUpdate,
-  updateEventName: 'update',
+  updateEventName: /** @type {'update'} */ ('update'),
  diffUpdate: Y.diffUpdate
 }

@ -44,7 +43,7 @@ export const encV2 = {
  mergeUpdates: Y.mergeUpdatesV2,
  applyUpdate: Y.applyUpdateV2,
  logUpdate: Y.logUpdateV2,
-  updateEventName: 'updateV2',
+  updateEventName: /** @type {'updateV2'} */ ('updateV2'),
  diffUpdate: Y.diffUpdateV2
 }

@ -134,7 +133,7 @@ export class TestYInstance extends Y.Doc {
   * @param {TestYInstance} remoteClient
   */
  _receive (message, remoteClient) {
-    map.setIfUndefined(this.receiving, remoteClient, () => []).push(message)
+    map.setIfUndefined(this.receiving, remoteClient, () => /** @type {Array<Uint8Array>} */ ([])).push(message)
  }
 }

@ -347,7 +346,7 @@ export const compare = users => {
    t.compare(userMapValues[i], userMapValues[i + 1])
    t.compare(userXmlValues[i], userXmlValues[i + 1])
    t.compare(userTextValues[i].map(/** @param {any} a */ a => typeof a.insert === 'string' ? a.insert : ' ').join('').length, users[i].getText('text').length)
-    t.compare(userTextValues[i], userTextValues[i + 1], '', (constructor, a, b) => {
+    t.compare(userTextValues[i], userTextValues[i + 1], '', (_constructor, a, b) => {
      if (a instanceof Y.AbstractType) {
        t.compare(a.toJSON(), b.toJSON())
      } else if (a !== b) {
@ -356,8 +355,9 @@ export const compare = users => {
      return true
    })
    t.compare(Y.encodeStateVector(users[i]), Y.encodeStateVector(users[i + 1]))
-    compareDS(Y.createDeleteSetFromStructStore(users[i].store), Y.createDeleteSetFromStructStore(users[i + 1].store))
+    Y.equalDeleteSets(Y.createDeleteSetFromStructStore(users[i].store), Y.createDeleteSetFromStructStore(users[i + 1].store))
    compareStructStores(users[i].store, users[i + 1].store)
+    t.compare(Y.encodeSnapshot(Y.snapshot(users[i])), Y.encodeSnapshot(Y.snapshot(users[i + 1])))
  }
  users.map(u => u.destroy())
 }
@ -370,8 +370,8 @@ export const compare = users => {
 export const compareItemIDs = (a, b) => a === b || (a !== null && b != null && Y.compareIDs(a.id, b.id))

 /**
- * @param {import('../src/internals').StructStore} ss1
- * @param {import('../src/internals').StructStore} ss2
+ * @param {import('../src/internals.js').StructStore} ss1
+ * @param {import('../src/internals.js').StructStore} ss2
 */
 export const compareStructStores = (ss1, ss2) => {
  t.assert(ss1.clients.size === ss2.clients.size)
@ -412,25 +412,6 @@ export const compareStructStores = (ss1, ss2) => {
  }
 }

-/**
- * @param {import('../src/internals').DeleteSet} ds1
- * @param {import('../src/internals').DeleteSet} ds2
- */
-export const compareDS = (ds1, ds2) => {
-  t.assert(ds1.clients.size === ds2.clients.size)
-  ds1.clients.forEach((deleteItems1, client) => {
-    const deleteItems2 = /** @type {Array<import('../src/internals').DeleteItem>} */ (ds2.clients.get(client))
-    t.assert(deleteItems2 !== undefined && deleteItems1.length === deleteItems2.length)
-    for (let i = 0; i < deleteItems1.length; i++) {
-      const di1 = deleteItems1[i]
-      const di2 = deleteItems2[i]
-      if (di1.clock !== di2.clock || di1.len !== di2.len) {
-        t.fail('DeleteSets dont match')
-      }
-    }
-  })
-}
-
 /**
 * @template T
 * @callback InitTestObjectCallback
--- a/tests/undo-redo.tests.js
+++ b/tests/undo-redo.tests.js
@ -1,8 +1,48 @@
-import { init, compare, applyRandomTests, Doc } from './testHelper.js' // eslint-disable-line
+import { init } from './testHelper.js' // eslint-disable-line

 import * as Y from '../src/index.js'
 import * as t from 'lib0/testing'

+export const testInconsistentFormat = () => {
+  /**
+   * @param {Y.Doc} ydoc
+   */
+  const testYjsMerge = ydoc => {
+    const content = /** @type {Y.XmlText} */ (ydoc.get('text', Y.XmlText))
+    content.format(0, 6, { bold: null })
+    content.format(6, 4, { type: 'text' })
+    t.compare(content.toDelta(), [
+      {
+        attributes: { type: 'text' },
+        insert: 'Merge Test'
+      },
+      {
+        attributes: { type: 'text', italic: true },
+        insert: ' After'
+      }
+    ])
+  }
+  const initializeYDoc = () => {
+    const yDoc = new Y.Doc({ gc: false })
+
+    const content = /** @type {Y.XmlText} */ (yDoc.get('text', Y.XmlText))
+    content.insert(0, ' After', { type: 'text', italic: true })
+    content.insert(0, 'Test', { type: 'text' })
+    content.insert(0, 'Merge ', { type: 'text', bold: true })
+    return yDoc
+  }
+  {
+    const yDoc = initializeYDoc()
+    testYjsMerge(yDoc)
+  }
+  {
+    const initialYDoc = initializeYDoc()
+    const yDoc = new Y.Doc({ gc: false })
+    Y.applyUpdate(yDoc, Y.encodeStateAsUpdate(initialYDoc))
+    testYjsMerge(yDoc)
+  }
+}
+
 /**
 * @param {t.TestCase} tc
 */
@ -64,9 +104,9 @@ export const testUndoText = tc => {

 /**
 * Test case to fix #241
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testEmptyTypeScope = tc => {
+export const testEmptyTypeScope = _tc => {
  const ydoc = new Y.Doc()
  const um = new Y.UndoManager([], { doc: ydoc })
  const yarray = ydoc.getArray()
@ -77,10 +117,76 @@ export const testEmptyTypeScope = tc => {
 }

 /**
- * Test case to fix #241
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testDoubleUndo = tc => {
+export const testRejectUpdateExample = _tc => {
+  const tmpydoc1 = new Y.Doc()
+  tmpydoc1.getArray('restricted').insert(0, [1])
+  tmpydoc1.getArray('public').insert(0, [1])
+  const update1 = Y.encodeStateAsUpdate(tmpydoc1)
+  const tmpydoc2 = new Y.Doc()
+  tmpydoc2.getArray('public').insert(0, [2])
+  const update2 = Y.encodeStateAsUpdate(tmpydoc2)
+
+  const ydoc = new Y.Doc()
+  const restrictedType = ydoc.getArray('restricted')
+
+  /**
+   * Assume this function handles incoming updates via a communication channel like websockets.
+   * Changes to the `ydoc.getMap('restricted')` type should be rejected.
+   *
+   * - set up undo manager on the restricted types
+   * - cache pending* updates from the Ydoc to avoid certain attacks
+   * - apply received update and check whether the restricted type (or any of its children) has been changed.
+   * - catch errors that might try to circumvent the restrictions
+   * - undo changes on restricted types
+   * - reapply pending* updates
+   *
+   * @param {Uint8Array} update
+   */
+  const updateHandler = (update) => {
+    // don't handle changes of the local undo manager, which is used to undo invalid changes
+    const um = new Y.UndoManager(restrictedType, { trackedOrigins: new Set(['remote change']) })
+    const beforePendingDs = ydoc.store.pendingDs
+    const beforePendingStructs = ydoc.store.pendingStructs?.update
+    try {
+      Y.applyUpdate(ydoc, update, 'remote change')
+    } finally {
+      while (um.undoStack.length) {
+        um.undo()
+      }
+      um.destroy()
+      ydoc.store.pendingDs = beforePendingDs
+      ydoc.store.pendingStructs = null
+      if (beforePendingStructs) {
+        Y.applyUpdateV2(ydoc, beforePendingStructs)
+      }
+    }
+  }
+  updateHandler(update1)
+  updateHandler(update2)
+  t.assert(restrictedType.length === 0)
+  t.assert(ydoc.getArray('public').length === 2)
+}
+
+/**
+ * Test case to fix #241
+ * @param {t.TestCase} _tc
+ */
+export const testGlobalScope = _tc => {
+  const ydoc = new Y.Doc()
+  const um = new Y.UndoManager(ydoc)
+  const yarray = ydoc.getArray()
+  yarray.insert(0, [1])
+  um.undo()
+  t.assert(yarray.length === 0)
+}
+
+/**
+ * Test case to fix #241
+ * @param {t.TestCase} _tc
+ */
+export const testDoubleUndo = _tc => {
  const doc = new Y.Doc()
  const text = doc.getText()
  text.insert(0, '1221')
@ -316,9 +422,9 @@ export const testUndoDeleteFilter = tc => {

 /**
 * This issue has been reported in https://discuss.yjs.dev/t/undomanager-with-external-updates/454/6
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testUndoUntilChangePerformed = tc => {
+export const testUndoUntilChangePerformed = _tc => {
  const doc = new Y.Doc()
  const doc2 = new Y.Doc()
  doc.on('update', update => Y.applyUpdate(doc2, update))
@ -347,9 +453,9 @@ export const testUndoUntilChangePerformed = tc => {

 /**
 * This issue has been reported in https://github.com/yjs/yjs/issues/317
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testUndoNestedUndoIssue = tc => {
+export const testUndoNestedUndoIssue = _tc => {
  const doc = new Y.Doc({ gc: false })
  const design = doc.getMap()
  const undoManager = new Y.UndoManager(design, { captureTimeout: 0 })
@ -403,9 +509,9 @@ export const testUndoNestedUndoIssue = tc => {
 /**
 * This issue has been reported in https://github.com/yjs/yjs/issues/355
 *
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testConsecutiveRedoBug = tc => {
+export const testConsecutiveRedoBug = _tc => {
  const doc = new Y.Doc()
  const yRoot = doc.getMap()
  const undoMgr = new Y.UndoManager(yRoot)
@ -454,9 +560,9 @@ export const testConsecutiveRedoBug = tc => {
 /**
 * This issue has been reported in https://github.com/yjs/yjs/issues/304
 *
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testUndoXmlBug = tc => {
+export const testUndoXmlBug = _tc => {
  const origin = 'origin'
  const doc = new Y.Doc()
  const fragment = doc.getXmlFragment('t')
@ -499,9 +605,9 @@ export const testUndoXmlBug = tc => {
 /**
 * This issue has been reported in https://github.com/yjs/yjs/issues/343
 *
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testUndoBlockBug = tc => {
+export const testUndoBlockBug = _tc => {
  const doc = new Y.Doc({ gc: false })
  const design = doc.getMap()

@ -559,9 +665,9 @@ export const testUndoBlockBug = tc => {
 * Undo text formatting delete should not corrupt peer state.
 *
 * @see https://github.com/yjs/yjs/issues/392
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testUndoDeleteTextFormat = tc => {
+export const testUndoDeleteTextFormat = _tc => {
  const doc = new Y.Doc()
  const text = doc.getText()
  text.insert(0, 'Attack ships on fire off the shoulder of Orion.')
@ -597,9 +703,9 @@ export const testUndoDeleteTextFormat = tc => {
 * Undo text formatting delete should not corrupt peer state.
 *
 * @see https://github.com/yjs/yjs/issues/392
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testBehaviorOfIgnoreremotemapchangesProperty = tc => {
+export const testBehaviorOfIgnoreremotemapchangesProperty = _tc => {
  const doc = new Y.Doc()
  const doc2 = new Y.Doc()
  doc.on('update', update => Y.applyUpdate(doc2, update, doc))
@ -620,9 +726,9 @@ export const testBehaviorOfIgnoreremotemapchangesProperty = tc => {
 * Special deletion case.
 *
 * @see https://github.com/yjs/yjs/issues/447
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testSpecialDeletionCase = tc => {
+export const testSpecialDeletionCase = _tc => {
  const origin = 'undoable'
  const doc = new Y.Doc()
  const fragment = doc.getXmlFragment()
@ -644,3 +750,64 @@ export const testSpecialDeletionCase = tc => {
  undoManager.undo()
  t.compareStrings(fragment.toString(), '<test a="1" b="2"></test>')
 }
+
+/**
+ * Deleted entries in a map should be restored on undo.
+ *
+ * @see https://github.com/yjs/yjs/issues/500
+ * @param {t.TestCase} tc
+ */
+export const testUndoDeleteInMap = (tc) => {
+  const { map0 } = init(tc, { users: 3 })
+  const undoManager = new Y.UndoManager(map0, { captureTimeout: 0 })
+  map0.set('a', 'a')
+  map0.delete('a')
+  map0.set('a', 'b')
+  map0.delete('a')
+  map0.set('a', 'c')
+  map0.delete('a')
+  map0.set('a', 'd')
+  t.compare(map0.toJSON(), { a: 'd' })
+  undoManager.undo()
+  t.compare(map0.toJSON(), {})
+  undoManager.undo()
+  t.compare(map0.toJSON(), { a: 'c' })
+  undoManager.undo()
+  t.compare(map0.toJSON(), {})
+  undoManager.undo()
+  t.compare(map0.toJSON(), { a: 'b' })
+  undoManager.undo()
+  t.compare(map0.toJSON(), {})
+  undoManager.undo()
+  t.compare(map0.toJSON(), { a: 'a' })
+}
+
+/**
+ * It should expose the StackItem being processed if undoing
+ *
+ * @param {t.TestCase} _tc
+ */
+export const testUndoDoingStackItem = async (_tc) => {
+  const doc = new Y.Doc()
+  const text = doc.getText('text')
+  const undoManager = new Y.UndoManager([text])
+  undoManager.on('stack-item-added', /** @param {any} event */ event => {
+    event.stackItem.meta.set('str', '42')
+  })
+  let metaUndo = /** @type {any} */ (null)
+  let metaRedo = /** @type {any} */ (null)
+  text.observe((event) => {
+    const /** @type {Y.UndoManager} */ origin = event.transaction.origin
+    if (origin === undoManager && origin.undoing) {
+      metaUndo = origin.currStackItem?.meta.get('str')
+    } else if (origin === undoManager && origin.redoing) {
+      metaRedo = origin.currStackItem?.meta.get('str')
+    }
+  })
+  text.insert(0, 'abc')
+  undoManager.undo()
+  undoManager.redo()
+  t.compare(metaUndo, '42', 'currStackItem is accessible while undoing')
+  t.compare(metaRedo, '42', 'currStackItem is accessible while redoing')
+  t.compare(undoManager.currStackItem, null, 'currStackItem is null after observe/transaction')
+}
--- a/tests/updates.tests.js
+++ b/tests/updates.tests.js
@ -4,6 +4,7 @@ import * as Y from '../src/index.js'
 import { readClientsStructRefs, readDeleteSet, UpdateDecoderV2, UpdateEncoderV2, writeDeleteSet } from '../src/internals.js'
 import * as encoding from 'lib0/encoding'
 import * as decoding from 'lib0/decoding'
+import * as object from 'lib0/object'

 /**
 * @typedef {Object} Enc
@ -14,7 +15,7 @@ import * as decoding from 'lib0/decoding'
 * @property {function(Uint8Array):{from:Map<number,number>,to:Map<number,number>}} Enc.parseUpdateMeta
 * @property {function(Y.Doc):Uint8Array} Enc.encodeStateVector
 * @property {function(Uint8Array):Uint8Array} Enc.encodeStateVectorFromUpdate
- * @property {string} Enc.updateEventName
+ * @property {'update'|'updateV2'} Enc.updateEventName
 * @property {string} Enc.description
 * @property {function(Uint8Array, Uint8Array):Uint8Array} Enc.diffUpdate
 */
@ -138,7 +139,6 @@ export const testKeyEncoding = tc => {
 */
 const checkUpdateCases = (ydoc, updates, enc, hasDeletes) => {
  const cases = []
-
  // Case 1: Simple case, simply merge everything
  cases.push(enc.mergeUpdates(updates))

@ -169,7 +169,7 @@ const checkUpdateCases = (ydoc, updates, enc, hasDeletes) => {
  // t.info('Target State: ')
  // enc.logUpdate(targetState)

-  cases.forEach((mergedUpdates, i) => {
+  cases.forEach((mergedUpdates) => {
    // t.info('State Case $' + i + ':')
    // enc.logUpdate(updates)
    const merged = new Y.Doc({ gc: false })
@ -218,10 +218,10 @@ const checkUpdateCases = (ydoc, updates, enc, hasDeletes) => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testMergeUpdates1 = tc => {
-  encoders.forEach((enc, i) => {
+export const testMergeUpdates1 = _tc => {
+  encoders.forEach((enc) => {
    t.info(`Using encoder: ${enc.description}`)
    const ydoc = new Y.Doc({ gc: false })
    const updates = /** @type {Array<Uint8Array>} */ ([])
@ -299,8 +299,59 @@ export const testMergePendingUpdates = tc => {
  Y.applyUpdate(yDoc5, update4)
  Y.applyUpdate(yDoc5, serverUpdates[4])
  // @ts-ignore
-  const update5 = Y.encodeStateAsUpdate(yDoc5) // eslint-disable-line
+  const _update5 = Y.encodeStateAsUpdate(yDoc5) // eslint-disable-line

  const yText5 = yDoc5.getText('textBlock')
  t.compareStrings(yText5.toString(), 'nenor')
 }
+
+/**
+ * @param {t.TestCase} _tc
+ */
+export const testObfuscateUpdates = _tc => {
+  const ydoc = new Y.Doc()
+  const ytext = ydoc.getText('text')
+  const ymap = ydoc.getMap('map')
+  const yarray = ydoc.getArray('array')
+  // test ytext
+  ytext.applyDelta([{ insert: 'text', attributes: { bold: true } }, { insert: { href: 'supersecreturl' } }])
+  // test ymap
+  ymap.set('key', 'secret1')
+  ymap.set('key', 'secret2')
+  // test yarray with subtype & subdoc
+  const subtype = new Y.XmlElement('secretnodename')
+  const subdoc = new Y.Doc({ guid: 'secret' })
+  subtype.setAttribute('attr', 'val')
+  yarray.insert(0, ['teststring', 42, subtype, subdoc])
+  // obfuscate the content and put it into a new document
+  const obfuscatedUpdate = Y.obfuscateUpdate(Y.encodeStateAsUpdate(ydoc))
+  const odoc = new Y.Doc()
+  Y.applyUpdate(odoc, obfuscatedUpdate)
+  const otext = odoc.getText('text')
+  const omap = odoc.getMap('map')
+  const oarray = odoc.getArray('array')
+  // test ytext
+  const delta = otext.toDelta()
+  t.assert(delta.length === 2)
+  t.assert(delta[0].insert !== 'text' && delta[0].insert.length === 4)
+  t.assert(object.length(delta[0].attributes) === 1)
+  t.assert(!object.hasProperty(delta[0].attributes, 'bold'))
+  t.assert(object.length(delta[1]) === 1)
+  t.assert(object.hasProperty(delta[1], 'insert'))
+  // test ymap
+  t.assert(omap.size === 1)
+  t.assert(!omap.has('key'))
+  // test yarray with subtype & subdoc
+  const result = oarray.toArray()
+  t.assert(result.length === 4)
+  t.assert(result[0] !== 'teststring')
+  t.assert(result[1] !== 42)
+  const osubtype = /** @type {Y.XmlElement} */ (result[2])
+  const osubdoc = result[3]
+  // test subtype
+  t.assert(osubtype.nodeName !== subtype.nodeName)
+  t.assert(object.length(osubtype.getAttributes()) === 1)
+  t.assert(osubtype.getAttribute('attr') === undefined)
+  // test subdoc
+  t.assert(osubdoc.guid !== subdoc.guid)
+}
--- a/tests/y-array.tests.js
+++ b/tests/y-array.tests.js
@ -4,6 +4,9 @@ import * as Y from '../src/index.js'
 import * as t from 'lib0/testing'
 import * as prng from 'lib0/prng'
 import * as math from 'lib0/math'
+import * as env from 'lib0/environment'
+
+const isDevMode = env.getVariable('node_env') === 'development'

 /**
 * @param {t.TestCase} tc
@ -17,6 +20,28 @@ export const testBasicUpdate = tc => {
  t.compare(doc2.getArray('array').toArray(), ['hi'])
 }

+/**
+ * @param {t.TestCase} tc
+ */
+export const testFailsObjectManipulationInDevMode = tc => {
+  if (isDevMode) {
+    t.info('running in dev mode')
+    const doc = new Y.Doc()
+    const a = [1, 2, 3]
+    const b = { o: 1 }
+    doc.getArray('test').insert(0, [a])
+    doc.getMap('map').set('k', b)
+    t.fails(() => {
+      a[0] = 42
+    })
+    t.fails(() => {
+      b.o = 42
+    })
+  } else {
+    t.info('not in dev mode')
+  }
+}
+
 /**
 * @param {t.TestCase} tc
 */
@ -32,6 +57,17 @@ export const testSlice = tc => {
  t.compareArrays(arr.slice(0, 2), [0, 1])
 }

+/**
+ * @param {t.TestCase} tc
+ */
+export const testArrayFrom = tc => {
+  const doc1 = new Y.Doc()
+  const db1 = doc1.getMap('root')
+  const nestedArray1 = Y.Array.from([0, 1, 2])
+  db1.set('array', nestedArray1)
+  t.compare(nestedArray1.toArray(), [0, 1, 2])
+}
+
 /**
 * Debugging yjs#297 - a critical bug connected to the search-marker approach
 *
@ -319,6 +355,29 @@ export const testObserveDeepEventOrder = tc => {
  }
 }

+/**
+ * Correct index when computing event.path in observeDeep - https://github.com/yjs/yjs/issues/457
+ *
+ * @param {t.TestCase} _tc
+ */
+export const testObservedeepIndexes = _tc => {
+  const doc = new Y.Doc()
+  const map = doc.getMap()
+  // Create a field with the array as value
+  map.set('my-array', new Y.Array())
+  // Fill the array with some strings and our Map
+  map.get('my-array').push(['a', 'b', 'c', new Y.Map()])
+  /**
+   * @type {Array<any>}
+   */
+  let eventPath = []
+  map.observeDeep((events) => { eventPath = events[0].path })
+  // set a value on the map inside of our array
+  map.get('my-array').get(3).set('hello', 'world')
+  console.log(eventPath)
+  t.compare(eventPath, ['my-array', 3])
+}
+
 /**
 * @param {t.TestCase} tc
 */
--- a/tests/y-map.tests.js
+++ b/tests/y-map.tests.js
@ -8,6 +8,54 @@ import * as Y from '../src/index.js'
 import * as t from 'lib0/testing'
 import * as prng from 'lib0/prng'

+/**
+ * @param {t.TestCase} _tc
+ */
+export const testIterators = _tc => {
+  const ydoc = new Y.Doc()
+  /**
+   * @type {Y.Map<number>}
+   */
+  const ymap = ydoc.getMap()
+  // we are only checking if the type assumptions are correct
+  /**
+   * @type {Array<number>}
+   */
+  const vals = Array.from(ymap.values())
+  /**
+   * @type {Array<[string,number]>}
+   */
+  const entries = Array.from(ymap.entries())
+  /**
+   * @type {Array<string>}
+   */
+  const keys = Array.from(ymap.keys())
+  console.log(vals, entries, keys)
+}
+
+/**
+ * Computing event changes after transaction should result in an error. See yjs#539
+ *
+ * @param {t.TestCase} _tc
+ */
+export const testMapEventError = _tc => {
+  const doc = new Y.Doc()
+  const ymap = doc.getMap()
+  /**
+   * @type {any}
+   */
+  let event = null
+  ymap.observe((e) => {
+    event = e
+  })
+  t.fails(() => {
+    t.info(event.keys)
+  })
+  t.fails(() => {
+    t.info(event.keys)
+  })
+}
+
 /**
 * @param {t.TestCase} tc
 */
@ -321,11 +369,11 @@ export const testObserversUsingObservedeep = tc => {
  /**
   * @type {Array<Array<string|number>>}
   */
-  const pathes = []
+  const paths = []
  let calls = 0
  map0.observeDeep(events => {
    events.forEach(event => {
-      pathes.push(event.path)
+      paths.push(event.path)
    })
    calls++
  })
@ -333,7 +381,35 @@ export const testObserversUsingObservedeep = tc => {
  map0.get('map').set('array', new Y.Array())
  map0.get('map').get('array').insert(0, ['content'])
  t.assert(calls === 3)
-  t.compare(pathes, [[], ['map'], ['map', 'array']])
+  t.compare(paths, [[], ['map'], ['map', 'array']])
+  compare(users)
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testPathsOfSiblingEvents = tc => {
+  const { users, map0 } = init(tc, { users: 2 })
+  /**
+   * @type {Array<Array<string|number>>}
+   */
+  const paths = []
+  let calls = 0
+  const doc = users[0]
+  map0.set('map', new Y.Map())
+  map0.get('map').set('text1', new Y.Text('initial'))
+  map0.observeDeep(events => {
+    events.forEach(event => {
+      paths.push(event.path)
+    })
+    calls++
+  })
+  doc.transact(() => {
+    map0.get('map').get('text1').insert(0, 'post-')
+    map0.get('map').set('text2', new Y.Text('new'))
+  })
+  t.assert(calls === 1)
+  t.compare(paths, [['map'], ['map', 'text1']])
  compare(users)
 }

@ -455,9 +531,9 @@ export const testChangeEvent = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testYmapEventExceptionsShouldCompleteTransaction = tc => {
+export const testYmapEventExceptionsShouldCompleteTransaction = _tc => {
  const doc = new Y.Doc()
  const map = doc.getMap('map')

--- a/tests/y-text.tests.js
+++ b/tests/y-text.tests.js
--- a/tests/y-xml.tests.js
+++ b/tests/y-xml.tests.js
@ -3,6 +3,33 @@ import * as Y from '../src/index.js'

 import * as t from 'lib0/testing'

+export const testCustomTypings = () => {
+  const ydoc = new Y.Doc()
+  const ymap = ydoc.getMap()
+  /**
+   * @type {Y.XmlElement<{ num: number, str: string, [k:string]: object|number|string }>}
+   */
+  const yxml = ymap.set('yxml', new Y.XmlElement('test'))
+  /**
+   * @type {number|undefined}
+   */
+  const num = yxml.getAttribute('num')
+  /**
+   * @type {string|undefined}
+   */
+  const str = yxml.getAttribute('str')
+  /**
+   * @type {object|number|string|undefined}
+   */
+  const dtrn = yxml.getAttribute('dtrn')
+  const attrs = yxml.getAttributes()
+  /**
+   * @type {object|number|string|undefined}
+   */
+  const any = attrs.shouldBeAny
+  console.log({ num, str, dtrn, attrs, any })
+}
+
 /**
 * @param {t.TestCase} tc
 */
@ -92,9 +119,9 @@ export const testTreewalker = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testYtextAttributes = tc => {
+export const testYtextAttributes = _tc => {
  const ydoc = new Y.Doc()
  const ytext = /** @type {Y.XmlText} */ (ydoc.get('', Y.XmlText))
  ytext.observe(event => {
@ -106,9 +133,9 @@ export const testYtextAttributes = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testSiblings = tc => {
+export const testSiblings = _tc => {
  const ydoc = new Y.Doc()
  const yxml = ydoc.getXmlFragment()
  const first = new Y.XmlText()
@ -122,9 +149,9 @@ export const testSiblings = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testInsertafter = tc => {
+export const testInsertafter = _tc => {
  const ydoc = new Y.Doc()
  const yxml = ydoc.getXmlFragment()
  const first = new Y.XmlText()
@ -152,9 +179,9 @@ export const testInsertafter = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testClone = tc => {
+export const testClone = _tc => {
  const ydoc = new Y.Doc()
  const yxml = ydoc.getXmlFragment()
  const first = new Y.XmlText('text')
@ -162,7 +189,6 @@ export const testClone = tc => {
  const third = new Y.XmlElement('p')
  yxml.push([first, second, third])
  t.compareArrays(yxml.toArray(), [first, second, third])
-
  const cloneYxml = yxml.clone()
  ydoc.getArray('copyarr').insert(0, [cloneYxml])
  t.assert(cloneYxml.length === 3)
@ -170,9 +196,9 @@ export const testClone = tc => {
 }

 /**
- * @param {t.TestCase} tc
+ * @param {t.TestCase} _tc
 */
-export const testFormattingBug = tc => {
+export const testFormattingBug = _tc => {
  const ydoc = new Y.Doc()
  const yxml = /** @type {Y.XmlText} */ (ydoc.get('', Y.XmlText))
  const delta = [
@ -183,3 +209,15 @@ export const testFormattingBug = tc => {
  yxml.applyDelta(delta)
  t.compare(yxml.toDelta(), delta)
 }
+
+/**
+ * @param {t.TestCase} _tc
+ */
+export const testElement = _tc => {
+  const ydoc = new Y.Doc()
+  const yxmlel = ydoc.getXmlElement()
+  const text1 = new Y.XmlText('text1')
+  const text2 = new Y.XmlText('text2')
+  yxmlel.insert(0, [text1, text2])
+  t.compareArrays(yxmlel.toArray(), [text1, text2])
+}
--- a/tsconfig.json
+++ b/tsconfig.json
@ -1,64 +1,21 @@
 {
  "compilerOptions": {
-    /* Basic Options */
-    "target": "es2018",
-    "lib": ["es2018", "dom"],                             /* Specify library files to be included in the compilation. */
-    "allowJs": true,                       /* Allow javascript files to be compiled. */
-    "checkJs": true,                       /* Report errors in .js files. */
-    // "jsx": "preserve",                     /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
-    "declaration": true,                   /* Generates corresponding '.d.ts' file. */
-    // "declarationMap": true,                /* Generates a sourcemap for each corresponding '.d.ts' file. */
-    // "sourceMap": true,                     /* Generates corresponding '.map' file. */
-    // "outFile": "./dist/yjs.js",                       /* Concatenate and emit output to single file. */
-    "outDir": "./dist",                        /* Redirect output structure to the directory. */
-    "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
-    // "composite": true,                     /* Enable project compilation */
-    // "removeComments": true,                /* Do not emit comments to output. */
-    // "noEmit": true,                        /* Do not emit outputs. */
-    // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
-    // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
-    // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
-
-    /* Strict Type-Checking Options */
-    "strict": true,                           /* Enable all strict type-checking options. */
-    "noImplicitAny": true,                 /* Raise error on expressions and declarations with an implied 'any' type. */
+    "target": "ES2021",
+    "lib": ["ES2021", "dom"],
+    "module": "node16",
+    "allowJs": true,
+    "checkJs": true,
+    "declaration": true,
+    "declarationMap": true,
+    "outDir": "./dist",
+    "baseUrl": "./",
    "emitDeclarationOnly": true,
-    // "strictNullChecks": true,              /* Enable strict null checks. */
-    // "strictFunctionTypes": true,           /* Enable strict checking of function types. */
-    // "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. */
-    // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
-    // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */
-
-    /* Additional Checks */
-    // "noUnusedLocals": true,                /* Report errors on unused locals. */
-    // "noUnusedParameters": true,            /* Report errors on unused parameters. */
-    // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
-    // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */
-
-    /* Module Resolution Options */
-    "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
-    "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
+    "strict": true,
+    "noImplicitAny": true,
+    "moduleResolution": "nodenext",
    "paths": {
      "yjs": ["./src/index.js"]
-    },                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
-    // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
-    // "typeRoots": [],                       /* List of folders to include type definitions from. */
-    // "types": [],                           /* Type declaration files to be included in compilation. */
-    // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
-    "esModuleInterop": true,                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
-    // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
-
-    /* Source Map Options */
-    // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */
-    // "mapRoot": "",                         /* Specify the location where debugger should locate map files instead of generated locations. */
-    // "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
-    // "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
-
-    /* Experimental Options */
-    // "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
-    // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
-    // "maxNodeModuleJsDepth": 0,
-    // "types": ["./src/utils/typedefs.js"]
+    }
  },
  "include": ["./src/**/*.js", "./tests/**/*.js"]
 }