diff --git a/src/Bindings/Binding.js b/src/Bindings/Binding.js
index 8ccab2c2..195550b0 100644
--- a/src/Bindings/Binding.js
+++ b/src/Bindings/Binding.js
@@ -2,7 +2,7 @@
 import { createMutualExclude } from '../Util/mutualExclude.js'
 
 /**
- * Abstract class for bindings
+ * Abstract class for bindings.
  *
  * A binding handles data binding from a Yjs type to a data object. For example,
  * you can bind a Quill editor instance to a YText instance with the `QuillBinding` class.
@@ -18,16 +18,27 @@ import { createMutualExclude } from '../Util/mutualExclude.js'
  */
 export default class Binding {
   /**
-   * @param {YType} type Yjs type
-   * @param {any} target Binding Target
+   * @param {YType} type Yjs type.
+   * @param {any} target Binding Target.
    */
   constructor (type, target) {
+    /**
+     * The Yjs type that is bound to `target`
+     * @type {YType}
+     */
     this.type = type
+    /**
+     * The target that `type` is bound to.
+     * @type {*}
+     */
     this.target = target
+    /**
+     * @private
+     */
     this._mutualExclude = createMutualExclude()
   }
   /**
-   * Remove all data observers (both from the type and th target).
+   * Remove all data observers (both from the type and the target).
    */
   destroy () {
     this.type = null
diff --git a/src/Bindings/DomBinding/DomBinding.js b/src/Bindings/DomBinding/DomBinding.js
index d8b06dab..0694b66a 100644
--- a/src/Bindings/DomBinding/DomBinding.js
+++ b/src/Bindings/DomBinding/DomBinding.js
@@ -17,9 +17,9 @@ import { removeAssociation } from './util.js'
  * This binding is automatically destroyed when its parent is deleted.
  *
  * @example
- *   const div = document.createElement('div')
- *   const type = y.define('xml', Y.XmlFragment)
- *   const binding = new Y.QuillBinding(type, div)
+ * const div = document.createElement('div')
+ * const type = y.define('xml', Y.XmlFragment)
+ * const binding = new Y.QuillBinding(type, div)
  *
  */
 export default class DomBinding extends Binding {
@@ -27,12 +27,28 @@ export default class DomBinding extends Binding {
    * @param {YXmlFragment} type The bind source. This is the ultimate source of
    *                            truth.
    * @param {Element} target The bind target. Mirrors the target.
+   * @param {Object} [opts] Optional configurations
+
+   * @param {FilterFunction} [opts.filter=defaultFilter] The filter function to use.
    */
   constructor (type, target, opts = {}) {
     // Binding handles textType as this.type and domTextarea as this.target
     super(type, target)
+    /**
+     * Maps each DOM element to the type that it is associated with.
+     * @type {Map}
+     */
     this.domToType = new Map()
+    /**
+     * Maps each YXml type to the DOM element that it is associated with.
+     * @type {Map}
+     */
     this.typeToDom = new Map()
+    /**
+     * Defines which DOM attributes and elements to filter out.
+     * Also filters remote changes.
+     * @type {FilterFunction}
+     */
     this.filter = opts.filter || defaultFilter
     // set initial value
     target.innerHTML = ''
@@ -103,6 +119,7 @@ export default class DomBinding extends Binding {
 
   /**
    * NOTE: currently does not apply filter to existing elements!
+   * @param {FilterFunction} filter The filter function to use from now on.
    */
   setFilter (filter) {
     this.filter = filter
@@ -110,7 +127,7 @@ export default class DomBinding extends Binding {
   }
 
   /**
-   * Remove all properties that are handled by this class
+   * Remove all properties that are handled by this class.
    */
   destroy () {
     this.domToType = null
@@ -125,3 +142,11 @@ export default class DomBinding extends Binding {
     super.destroy()
   }
 }
+
+  /**
+   * A filter defines which elements and attributes to share.
+   * Return null if the node should be filtered. Otherwise return the Map of
+   * accepted attributes.
+   *
+   * @typedef {function(nodeName: String, attrs: Map): Map|null} FilterFunction
+   */
diff --git a/src/Bindings/DomBinding/domObserver.js b/src/Bindings/DomBinding/domObserver.js
index f0f4d6bb..8304c079 100644
--- a/src/Bindings/DomBinding/domObserver.js
+++ b/src/Bindings/DomBinding/domObserver.js
@@ -7,7 +7,7 @@ import {
 import diff from '../../Util/simpleDiff.js'
 import YXmlFragment from '../../Types/YXml/YXmlFragment.js'
 
-/*
+/**
  * 1. Check if any of the nodes was deleted
  * 2. Iterate over the children.
  *    2.1 If a node exists that is not yet bound to a type, insert a new node
@@ -17,6 +17,7 @@ import YXmlFragment from '../../Types/YXml/YXmlFragment.js'
  *       recreate a new yxml element that is bound to that node.
  *       You can detect that a node was moved because expectedId
  *       !== actualId in the list
+ * @private
  */
 function applyChangesFromDom (binding, dom, yxml, _document) {
   if (yxml == null || yxml === false || yxml.constructor === YXmlHook) {
@@ -79,6 +80,9 @@ function applyChangesFromDom (binding, dom, yxml, _document) {
   }
 }
 
+/**
+ * @private
+ */
 export default function domObserver (mutations, _document) {
   this._mutualExclude(() => {
     this.type._y.transact(() => {
diff --git a/src/Bindings/DomBinding/domToType.js b/src/Bindings/DomBinding/domToType.js
index ddf21a6d..d95f8d28 100644
--- a/src/Bindings/DomBinding/domToType.js
+++ b/src/Bindings/DomBinding/domToType.js
@@ -5,7 +5,11 @@ import { createAssociation } from './util.js'
 /**
  * Creates a Yjs type (YXml) based on the contents of a DOM Element.
  *
- * @param {Element|TextNode}
+ * @param {Element|TextNode} element The DOM Element
+ * @param {?Document} _document Optional. Provide the global document object.
+ * @param {?DomBinding} binding This property should only be set if the type
+ *                              is going to be bound with the dom-binding.
+ * @return {YXmlElement | YXmlText}
  */
 export default function domToType (element, _document = document, binding) {
   let type
diff --git a/src/Bindings/DomBinding/filter.js b/src/Bindings/DomBinding/filter.js
index e9cb8b87..81fac728 100644
--- a/src/Bindings/DomBinding/filter.js
+++ b/src/Bindings/DomBinding/filter.js
@@ -1,10 +1,27 @@
 import isParentOf from '../../Util/isParentOf.js'
 
+/**
+ * Default filter method (does nothing).
+ *
+ * @param {String} nodeName The nodeName of the element
+ * @param {Map} attrs Map of key-value pairs that are attributes of the node.
+ * @return {Map | null} The allowed attributes or null, if the element should be
+ *                      filtered.
+ */
 export function defaultFilter (nodeName, attrs) {
+  // TODO: implement basic filter that filters out dangerous properties!
   return attrs
 }
 
-
+/**
+ * Applies a filter on a type.
+ *
+ * @param {Y} y The Yjs instance.
+ * @param {DomBinding} binding The DOM binding instance that has the dom filter.
+ * @param {YXmlElement | YXmlFragment } type The type to apply the filter to.
+ *
+ * @private
+ */
 export function applyFilterOnType (y, binding, type) {
   if (isParentOf(binding.type, type)) {
     const nodeName = type.nodeName
diff --git a/src/Bindings/DomBinding/selection.js b/src/Bindings/DomBinding/selection.js
index 551f4e87..366a1db9 100644
--- a/src/Bindings/DomBinding/selection.js
+++ b/src/Bindings/DomBinding/selection.js
@@ -5,6 +5,9 @@ import { getRelativePosition, fromRelativePosition } from '../../Util/relativePo
 let browserSelection = null
 let relativeSelection = null
 
+/**
+ * @private
+ */
 export let beforeTransactionSelectionFixer
 if (typeof getSelection !== 'undefined') {
   beforeTransactionSelectionFixer = function _beforeTransactionSelectionFixer (y, domBinding, transaction, remote) {
@@ -30,6 +33,9 @@ if (typeof getSelection !== 'undefined') {
   beforeTransactionSelectionFixer = function _fakeBeforeTransactionSelectionFixer () {}
 }
 
+/**
+ * @private
+ */
 export function afterTransactionSelectionFixer (y, domBinding, transaction, remote) {
   if (relativeSelection === null || !remote) {
     return
diff --git a/src/Bindings/DomBinding/typeObserver.js b/src/Bindings/DomBinding/typeObserver.js
index 46f8c79d..e5b4343a 100644
--- a/src/Bindings/DomBinding/typeObserver.js
+++ b/src/Bindings/DomBinding/typeObserver.js
@@ -3,6 +3,9 @@ import YXmlText from '../../Types/YXml/YXmlText.js'
 import YXmlHook from '../../Types/YXml/YXmlHook.js'
 import { removeDomChildrenUntilElementFound } from './util.js'
 
+/**
+ * @private
+ */
 export default function typeObserver (events, _document) {
   this._mutualExclude(() => {
     events.forEach(event => {
diff --git a/src/Bindings/DomBinding/util.js b/src/Bindings/DomBinding/util.js
index f8e5c94c..5396766b 100644
--- a/src/Bindings/DomBinding/util.js
+++ b/src/Bindings/DomBinding/util.js
@@ -1,6 +1,11 @@
 
 import domToType from './domToType.js'
 
+/**
+ * Iterates items until an undeleted item is found.
+ *
+ * @private
+ */
 export function iterateUntilUndeleted (item) {
   while (item !== null && item._deleted) {
     item = item._right
@@ -8,11 +13,23 @@ export function iterateUntilUndeleted (item) {
   return item
 }
 
+/**
+ * Removes an association (the information that a DOM element belongs to a
+ * type).
+ *
+ * @private
+ */
 export function removeAssociation (domBinding, dom, type) {
   domBinding.domToType.delete(dom)
   domBinding.typeToDom.delete(type)
 }
 
+/**
+ * Creates an association (the information that a DOM element belongs to a
+ * type).
+ *
+ * @private
+ */
 export function createAssociation (domBinding, dom, type) {
   if (domBinding !== undefined) {
     domBinding.domToType.set(dom, type)
@@ -31,12 +48,18 @@ export function createAssociation (domBinding, dom, type) {
  *                           the beginning.
  * @param {Array<Element>} doms The Dom elements to insert.
  * @param {?Document} _document Optional. Provide the global document object.
+ * @param {DomBinding} binding The dom binding
  * @return {Array<YXmlElement>} The YxmlElements that are inserted.
+ *
+ * @private
  */
 export function insertDomElementsAfter (type, prev, doms, _document, binding) {
   return type.insertAfter(prev, doms.map(dom => domToType(dom, _document, binding)))
 }
 
+/**
+ * @private
+ */
 export function insertNodeHelper (yxml, prevExpectedNode, child, _document, binding) {
   let insertedNodes = insertDomElementsAfter(yxml, prevExpectedNode, [child], _document, binding)
   if (insertedNodes.length > 0) {
@@ -54,6 +77,8 @@ export function insertNodeHelper (yxml, prevExpectedNode, child, _document, bind
  * @param {Element} currentChild Start removing elements with `currentChild`. If
  *                               `currentChild` is `elem` it won't be removed.
  * @param {Element|null} elem The elemnt to look for.
+ *
+ * @private
  */
 export function removeDomChildrenUntilElementFound (parent, currentChild, elem) {
   while (currentChild !== elem) {
diff --git a/src/Connector.js b/src/Connector.js
index a76fd687..654a2e9f 100644
--- a/src/Connector.js
+++ b/src/Connector.js
@@ -7,6 +7,8 @@ import { integrateRemoteStructs } from './MessageHandler/integrateRemoteStructs.
 
 import debug from 'debug'
 
+// TODO: rename Connector
+
 export default class AbstractConnector {
   constructor (y, opts) {
     this.y = y
diff --git a/src/Persistence.js b/src/Persistence.js
index 851e868a..20fc9178 100644
--- a/src/Persistence.js
+++ b/src/Persistence.js
@@ -14,7 +14,6 @@ function getFreshCnf () {
 }
 
 /**
- * @private
  * Abstract persistence class.
  */
 export default class AbstractPersistence {
diff --git a/src/Transaction.js b/src/Transaction.js
index 4b372fdf..237ed166 100644
--- a/src/Transaction.js
+++ b/src/Transaction.js
@@ -1,26 +1,69 @@
 
 /**
- * Changes that are created within a transaction are bundled and sent as one
- * message to the remote peers. This implies that the changes are applied
- * in one flush and at most one {@link YEvent} per type is created.
+ * A transaction is created for every change on the Yjs model. It is possible
+ * to bundle changes on the Yjs model in a single transaction to
+ * minimize the number on messages sent and the number of observer calls.
+ * If possible the user of this library should bundle as many changes as
+ * possible. Here is an example to illustrate the advantages of bundling:
+ *
+ * @example
+ * const map = y.define('map', YMap)
+ * // Log content when change is triggered
+ * map.observe(function () {
+ *   console.log('change triggered')
+ * })
+ * // Each change on the map type triggers a log message:
+ * map.set('a', 0) // => "change triggered"
+ * map.set('b', 0) // => "change triggered"
+ * // When put in a transaction, it will trigger the log after the transaction:
+ * y.transact(function () {
+ *   map.set('a', 1)
+ *   map.set('b', 1)
+ * }) // => "change triggered"
  *
- * It is best to bundle as many changes in a single Transaction as possible.
- * This way only few changes need to be computed
  */
 export default class Transaction {
   constructor (y) {
+    /**
+     * @type {Y} The Yjs instance.
+     */
     this.y = y
-    // types added during transaction
+    /**
+     * All new types that are added during a transaction.
+     * @type {Set<Item>}
+     */
     this.newTypes = new Set()
-    // changed types (does not include new types)
-    // maps from type to parentSubs (item._parentSub = null for array elements)
+    /**
+     * All types that were directly modified (property added or child
+     * inserted/deleted). New types are not included in this Set.
+     * Maps from type to parentSubs (`item._parentSub = null` for YArray)
+     * @type {Set<YType,String>}
+     */
     this.changedTypes = new Map()
+    // TODO: rename deletedTypes
+    /**
+     * Set of all deleted Types and Structs.
+     * @type {Set<Item>}
+     */
     this.deletedStructs = new Set()
+    /**
+     * Saves the old state set of the Yjs instance. If a state was modified,
+     * the original value is saved here.
+     * @type {Map<Number,Number>}
+     */
     this.beforeState = new Map()
+    /**
+     * Stores the events for the types that observe also child elements.
+     * It is mainly used by `observeDeep`.
+     * @type {Map<YType,Array<YEvent>>}
+     */
     this.changedParentTypes = new Map()
   }
 }
 
+/**
+ * @private
+ */
 export function transactionTypeChanged (y, type, sub) {
   if (type !== y && !type._deleted && !y._transaction.newTypes.has(type)) {
     const changedTypes = y._transaction.changedTypes
diff --git a/src/Util/Binary/Encoder.js b/src/Util/Binary/Encoder.js
index 42e561e4..53e09260 100644
--- a/src/Util/Binary/Encoder.js
+++ b/src/Util/Binary/Encoder.js
@@ -9,6 +9,7 @@ const bits8 = 0b11111111
 export default class BinaryEncoder {
   constructor () {
     // TODO: implement chained Uint8Array buffers instead of Array buffer
+    // TODO: Rewrite all methods as functions!
     this.data = []
   }
 
diff --git a/src/Util/Tree.js b/src/Util/Tree.js
index 7cca3767..d39060a3 100644
--- a/src/Util/Tree.js
+++ b/src/Util/Tree.js
@@ -467,5 +467,4 @@ export default class Tree {
       }
     }
   }
-  flush () {}
 }
diff --git a/src/Util/UndoManager.js b/src/Util/UndoManager.js
index a074ce7c..56cf2d95 100644
--- a/src/Util/UndoManager.js
+++ b/src/Util/UndoManager.js
@@ -1,4 +1,5 @@
 import ID from './ID/ID.js'
+import isParentOf from './isParentOf.js'
 
 class ReverseOperation {
   constructor (y, transaction) {
@@ -15,16 +16,6 @@ class ReverseOperation {
   }
 }
 
-function isStructInScope (y, struct, scope) {
-  while (struct !== y) {
-    if (struct === scope) {
-      return true
-    }
-    struct = struct._parent
-  }
-  return false
-}
-
 function applyReverseOperation (y, scope, reverseBuffer) {
   let performedUndo = false
   y.transact(() => {
@@ -38,7 +29,7 @@ function applyReverseOperation (y, scope, reverseBuffer) {
           while (op._deleted && op._redone !== null) {
             op = op._redone
           }
-          if (op._deleted === false && isStructInScope(y, op, scope)) {
+          if (op._deleted === false && isParentOf(scope, op)) {
             performedUndo = true
             op._delete(y)
           }
@@ -46,7 +37,7 @@ function applyReverseOperation (y, scope, reverseBuffer) {
       }
       for (let op of undoOp.deletedStructs) {
         if (
-          isStructInScope(y, op, scope) &&
+          isParentOf(scope, op) &&
           op._parent !== y &&
           (
             op._id.user !== y.userID ||
diff --git a/src/Util/YEvent.js b/src/Util/YEvent.js
index 1af22be4..b9096db9 100644
--- a/src/Util/YEvent.js
+++ b/src/Util/YEvent.js
@@ -7,7 +7,15 @@ export default class YEvent {
    * @param {YType} target The changed type.
    */
   constructor (target) {
+    /**
+     * The type on which this event was created on.
+     * @type {YType}
+     */
     this.target = target
+    /**
+     * The current target on which the observe callback is called.
+     * @type {YType}
+     */
     this.currentTarget = target
   }
 
diff --git a/src/Util/generateUserID.js b/src/Util/generateRandomUint32.js
similarity index 90%
rename from src/Util/generateUserID.js
rename to src/Util/generateRandomUint32.js
index d6f18701..23ac9b27 100644
--- a/src/Util/generateUserID.js
+++ b/src/Util/generateRandomUint32.js
@@ -1,6 +1,6 @@
 /* global crypto */
 
-export function generateUserID () {
+export function generateRandomUint32 () {
   if (typeof crypto !== 'undefined' && crypto.getRandomValue != null) {
     // browser
     let arr = new Uint32Array(1)
diff --git a/src/Util/isParentOf.js b/src/Util/isParentOf.js
index 76c3deab..f56b5f66 100644
--- a/src/Util/isParentOf.js
+++ b/src/Util/isParentOf.js
@@ -5,6 +5,8 @@
  * @param {Type} parent
  * @param {Type} child
  * @return {Boolean} Whether `parent` is a parent of `child`.
+ *
+ * @public
  */
 export default function isParentOf (parent, child) {
   child = child._parent
diff --git a/src/Util/mutualExclude.js b/src/Util/mutualExclude.js
index 519dfd50..9a83fa29 100644
--- a/src/Util/mutualExclude.js
+++ b/src/Util/mutualExclude.js
@@ -1,4 +1,22 @@
 
+// TODO: rename mutex
+
+/**
+ * Creates a mutual exclude function with the following property:
+ *
+ * @example
+ * const mutualExclude = createMutualExclude()
+ * mutualExclude(function () {
+ *   // This function is immediately executed
+ *   mutualExclude(function () {
+ *     // This function is never executed, as it is called with the same
+ *     // mutualExclude
+ *   })
+ * })
+ *
+ * @return {Function} A mutual exclude function
+ * @public
+ */
 export function createMutualExclude () {
   var token = true
   return function mutualExclude (f) {
diff --git a/src/Util/relativePosition.js b/src/Util/relativePosition.js
index 31974fcf..05b6b5d9 100644
--- a/src/Util/relativePosition.js
+++ b/src/Util/relativePosition.js
@@ -1,6 +1,8 @@
 import ID from './ID/ID.js'
 import RootID from './ID/RootID.js'
 
+// TODO: Implement function to describe ranges
+
 /**
  * A relative position that is based on the Yjs model. In contrast to an
  * absolute position (position by index), the relative position can be
diff --git a/src/Util/simpleDiff.js b/src/Util/simpleDiff.js
index adf3222b..d5154eb8 100644
--- a/src/Util/simpleDiff.js
+++ b/src/Util/simpleDiff.js
@@ -11,16 +11,16 @@
  * a === b // values match
  *
  * @typedef {Object} SimpleDiff
- * @property {NaturalNumber} pos The index where changes were applied
- * @property {NaturalNumber} delete The number of characters to delete starting
+ * @property {Number} pos The index where changes were applied
+ * @property {Number} delete The number of characters to delete starting
  *                                  at `index`.
  * @property {String} insert The new text to insert at `index` after applying
  *                           `delete`
  */
 
 /**
- * Create a diff between two strings. This diff implementation is intentionally
- * not very smart.
+ * Create a diff between two strings. This diff implementation is highly
+ * efficient, but not very sophisticated.
  *
  * @public
  * @param {String} a The old version of the string
diff --git a/src/Util/structReferences.js b/src/Util/structReferences.js
index ff9164c7..4101e455 100644
--- a/src/Util/structReferences.js
+++ b/src/Util/structReferences.js
@@ -12,15 +12,30 @@ import ItemEmbed from '../Struct/ItemEmbed.js'
 const structs = new Map()
 const references = new Map()
 
+/**
+ * Register a new Yjs types. The same type must be defined with the same
+ * reference on all clients!
+ *
+ * @param {Number} reference
+ * @param {class} structConstructor
+ *
+ * @public
+ */
 export function registerStruct (reference, structConstructor) {
   structs.set(reference, structConstructor)
   references.set(structConstructor, reference)
 }
 
+/**
+ * @private
+ */
 export function getStruct (reference) {
   return structs.get(reference)
 }
 
+/**
+ * @private
+ */
 export function getStructReference (typeConstructor) {
   return references.get(typeConstructor)
 }
diff --git a/src/Util/writeJSONToType.js b/src/Util/writeJSONToType.js
deleted file mode 100644
index 5dad6d29..00000000
--- a/src/Util/writeJSONToType.js
+++ /dev/null
@@ -1,33 +0,0 @@
-
-import YMap from '../Types/YMap'
-import YArray from '../Types/YArray'
-
-export function writeObjectToYMap (object, type) {
-  for (var key in object) {
-    var val = object[key]
-    if (Array.isArray(val)) {
-      type.set(key, YArray)
-      writeArrayToYArray(val, type.get(key))
-    } else if (typeof val === 'object') {
-      type.set(key, YMap)
-      writeObjectToYMap(val, type.get(key))
-    } else {
-      type.set(key, val)
-    }
-  }
-}
-
-export function writeArrayToYArray (array, type) {
-  for (var i = array.length - 1; i >= 0; i--) {
-    var val = array[i]
-    if (Array.isArray(val)) {
-      type.insert(0, [YArray])
-      writeArrayToYArray(val, type.get(0))
-    } else if (typeof val === 'object') {
-      type.insert(0, [YMap])
-      writeObjectToYMap(val, type.get(0))
-    } else {
-      type.insert(0, [val])
-    }
-  }
-}
diff --git a/src/Y.js b/src/Y.js
index ae81f937..ca7b63ef 100644
--- a/src/Y.js
+++ b/src/Y.js
@@ -1,19 +1,13 @@
 import DeleteStore from './Store/DeleteStore.js'
 import OperationStore from './Store/OperationStore.js'
 import StateStore from './Store/StateStore.js'
-import { generateUserID } from './Util/generateUserID.js'
+import { generateRandomUint32 } from './Util/generateRandomUint32.js'
 import RootID from './Util/ID/RootID.js'
 import NamedEventHandler from './Util/NamedEventHandler.js'
 import Transaction from './Transaction.js'
 
 export { default as DomBinding } from './Bindings/DomBinding/DomBinding.js'
 
-/**
- * A positive natural number including zero: 0, 1, 2, ..
- *
- * @typedef {number} NaturalNumber
- */
-
 /**
  * Anything that can be encoded with `JSON.stringify` and can be decoded with
  * `JSON.parse`.
@@ -47,7 +41,7 @@ export default class Y extends NamedEventHandler {
     this._contentReady = false
     this._opts = opts
     if (typeof opts.userID !== 'number') {
-      this.userID = generateUserID()
+      this.userID = generateRandomUint32()
     } else {
       this.userID = opts.userID
     }
diff --git a/test/encode-decode.tests.js b/test/encode-decode.tests.js
index f4b4ee45..e032d06b 100644
--- a/test/encode-decode.tests.js
+++ b/test/encode-decode.tests.js
@@ -1,7 +1,7 @@
 import { test } from '../node_modules/cutest/cutest.mjs'
 import BinaryEncoder from '../src/Util/Binary/Encoder.js'
 import BinaryDecoder from '../src/Util/Binary/Decoder.js'
-import { generateUserID } from '../src/Util/generateUserID.js'
+import { generateRandomUint32 } from '../src/Util/generateRandomUint32.js'
 import Chance from 'chance'
 
 function testEncoding (t, write, read, val) {
@@ -43,7 +43,7 @@ test('varUint random', async function varUintRandom (t) {
 
 test('varUint random user id', async function varUintRandomUserId (t) {
   t.getSeed() // enforces that this test is repeated
-  testEncoding(t, writeVarUint, readVarUint, generateUserID())
+  testEncoding(t, writeVarUint, readVarUint, generateRandomUint32())
 })
 
 const writeVarString = (encoder, val) => encoder.writeVarString(val)
diff --git a/tests-lib/helper.js b/tests-lib/helper.js
index d4bf1ea4..26a50f08 100644
--- a/tests-lib/helper.js
+++ b/tests-lib/helper.js
@@ -156,7 +156,7 @@ export async function initArrays (t, opts) {
     users: []
   }
   var chance = opts.chance || new Chance(t.getSeed() * 1000000000)
-  var conn = Object.assign({ room: 'debugging_' + t.name, generateUserId: false, testContext: t, chance }, connector)
+  var conn = Object.assign({ room: 'debugging_' + t.name, testContext: t, chance }, connector)
   for (let i = 0; i < opts.users; i++) {
     let connOpts
     if (i === 0) {