# DocumentCompare

class

`DocumentCompare` provides a set of tools that allows you to process editor document data by custom external logic, evaluate the differences between original and processed data, and apply them as granular changes or tracked suggestions.

Contrary to `editor.setData()`, this does not replace the whole editor data. Instead, atomic changes are evaluated and a small set of changes is applied to the document. This is especially useful when the editor also uses Track Changes, Revision History, and Real-Time Collaboration features.

Use [`process()`](#function-process), to run the whole pipeline in one call - it makes a [document snapshot](module_ai_toolkit_documentsnapshot-DocumentCompareSnapshot.md), processes the data, and applies granular changes:

```typescript
await documentCompare.process( async snapshot => externalDataProcessing( snapshot.content ) );

// Or, to apply changes as suggestions:
await documentCompare.process( async snapshot => externalDataProcessing( snapshot.content ), { asSuggestions: true } );
```

Some integrations need to process the data in separate steps (e.g. backend processing workflows, or when changes are not applied immediately to the content). In this case, you can capture a snapshot first and apply the result later:

```typescript
const snapshot = documentCompare.makeSnapshot();
const processed = await externalDataProcessing( snapshot.content );

// ...

const patch = documentCompare.computePatch( snapshot, processed, { asSuggestions: true } );
documentCompare.applyPatch( patch );
```

If the user should decide whether changes are accepted or rejected, compare the snapshot into separate changes instead, and apply the ones they keep:

```typescript
const changes = documentCompare.computeChanges( snapshot, processed );

documentCompare.applyChange( changes[ 0 ] );
```

See also [`ProposedChanges` plugin](module_ai_toolkit_proposedchanges-ProposedChanges.md), a set of tools to display the proposed changes to the user.

The snapshot data is stamped with `data-id` attributes, and the comparison pairs the elements of the snapshot and the processed data by these ids. When the processing cannot retain the ids (for example, when the data goes through Markdown), capture the snapshot without them. The elements are then paired by their content instead:

```typescript
const snapshot = documentCompare.makeSnapshot( { useDataIds: false } );
const processed = await externalDataProcessing( snapshot.content );

const patch = documentCompare.computePatch( snapshot, processed );
documentCompare.applyPatch( patch );
```

A document from outside the editor (for example, another version of the document) can be compared with the current document present in the editor. Capture the snapshot without the ids just before the comparison, so the documents are compared by content similarity:

```typescript
const snapshot = documentCompare.makeSnapshot( { useDataIds: false } );
const patch = documentCompare.computePatch( snapshot, importedHtml, { asSuggestions: true } );
documentCompare.applyPatch( patch );
```

The recommended way to use `DocumentCompare` is to create a snapshot with data IDs, then process the snapshot `content`, and then use the snapshot to generate the changes using `DocumentCompare` methods. This approach will result in better performance and the best diff quality, as snapshot data IDs are used by the diff algorithm to pair the elements. Skip IDs only in cases where they cannot be used.

<a id="properties"></a>

## Properties

<a id="member-editor"></a>

### `editor: Editor` _(readonly)_

The editor instance.

Note that most editors implement the [`ui`](module_core_editor_editor-Editor.md#member-ui) property. However, editors with an external UI (i.e. Bootstrap-based) or a headless editor may not have this property or throw an error when accessing it.

Because of above, to make plugins more universal, it is recommended to split features into:

* The "editing" part that uses the [`Editor`](module_core_editor_editor-Editor.md) class without `ui` property.
* The "UI" part that uses the [`Editor`](module_core_editor_editor-Editor.md) class and accesses `ui` property.

<a id="member-isEnabled"></a>

### `isEnabled: boolean` _(readonly)_

Flag indicating whether a plugin is enabled or disabled. A disabled plugin will not transform text.

Plugin can be simply disabled like that:

```typescript
// Disable the plugin so that no toolbars are visible.
editor.plugins.get( 'TextTransformation' ).isEnabled = false;
```

You can also use [`forceDisabled`](#function-forceDisabled) method.

#### Static properties

<a id="static-member-isContextPlugin"></a>

### `isContextPlugin: false` _(readonly)_

<a id="static-member-pluginName"></a>

### `pluginName: 'DocumentCompare'` _(readonly)_

<a id="static-member-requires"></a>

### `requires: readonly [ PluginConstructor<Editor> & new ( context: Editor ) => DocumentDiffer, PluginConstructor<Editor> & new ( context: Editor ) => DocumentCompareUtils, PluginConstructor<Editor> & new ( context: Editor ) => SuggestionsConversion, PluginConstructor<Editor> & new ( context: Editor ) => AIEditorConfig ]` _(readonly)_

<a id="methods"></a>

## Methods

<a id="function-constructor"></a>

### `constructor( editor )` _(inherited)_

#### Parameters

* `editor: Editor`

<a id="function-afterInit"></a>

### `afterInit() → void`

#### Returns

* `void`

<a id="function-applyChange"></a>

### `applyChange( change, options ) → void`

Applies a single [document change](module_ai_toolkit_proposedchange-DocumentChange.md) the same way [`applyPatch`](#function-applyPatch) applies a whole patch. See [`applyPatch`](#function-applyPatch).

#### Parameters

* `change: DocumentChange`

  The change to apply.

* `options: DocumentCompareApplyChangeOptions`

  How the change is applied.

  Defaults to `{}`

#### Returns

* `void`

<a id="function-applyPatch"></a>

### `applyPatch( patch ) → void`

Applies a patch to the current state of the document.

As a result, all changes described by the patch are reflected in the document. Note that this converges with all changes that happened on the document after the snapshot used for the patch was made, including both local and remote edits (if real-time collaboration is enabled).

Note that the patch can only be applied to the same document as the snapshot, and only during the same editing session. Otherwise, the method throws `documentcompare-channel-mismatch` or `documentcompare-session-mismatch`.

The patch is first validated against a copy of the document before anything is committed. If any errors or conflict resolution problems surface during this dry-run, `documentcompare-invalid-patch` error is thrown, and the editor data is left intact.

The changes can be applied directly to the content or as tracked suggestions (requires [Track changes plugin](module_track-changes_trackchanges-TrackChanges.md), otherwise `documentcompare-no-track-changes` is thrown). See also [`computePatch`](#function-computePatch).

#### Parameters

* `patch: DocumentComparePatch`

  The patch to apply, as produced by [`computePatch`](#function-computePatch).

#### Returns

* `void`

<a id="function-bind:DUAL_BIND"></a>

### `bind( bindProperty1, bindProperty2 ) → ObservableDualBindChain<K1, DocumentCompare[ K1 ], K2, DocumentCompare[ K2 ]>` _(inherited)_

Binds [observable properties](#function-set:KEY_VALUE) to other objects implementing the [`Observable`](module_utils_observablemixin-Observable.md) interface.

Read more in the [dedicated](../framework/deep-dive/observables.md#property-bindings) guide covering the topic of property bindings with some additional examples.

Consider two objects: a `button` and an associated `command` (both `Observable`).

A simple property binding could be as follows:

```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled' );
```

or even shorter:

```typescript
button.bind( 'isEnabled' ).to( command );
```

which works in the following way:

* `button.isEnabled` **instantly equals** `command.isEnabled`,
* whenever `command.isEnabled` changes, `button.isEnabled` will immediately reflect its value.

**Note**: To release the binding, use [`unbind`](module_utils_observablemixin-Observable.md#function-unbind).

You can also "rename" the property in the binding by specifying the new name in the `to()` chain:

```typescript
button.bind( 'isEnabled' ).to( command, 'isWorking' );
```

It is possible to bind more than one property at a time to shorten the code:

```typescript
button.bind( 'isEnabled', 'value' ).to( command );
```

which corresponds to:

```typescript
button.bind( 'isEnabled' ).to( command );
button.bind( 'value' ).to( command );
```

The binding can include more than one observable, combining multiple data sources in a custom callback:

```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible',
	( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible );
```

Using a custom callback allows processing the value before passing it to the target property:

```typescript
button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );
```

It is also possible to bind to the same property in an array of observables. To bind a `button` to multiple commands (also `Observables`) so that each and every one of them must be enabled for the button to become enabled, use the following code:

```typescript
button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
	( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
```

#### Type parameters

* * `K1`
  * `K2`

#### Parameters

* `bindProperty1: K1`

  Observable property that will be bound to other observable(s).

* `bindProperty2: K2`

  Observable property that will be bound to other observable(s).

#### Returns

* `ObservableDualBindChain<K1, DocumentCompare[ K1 ], K2, DocumentCompare[ K2 ]>`

  The bind chain with the `to()` and `toMany()` methods.

<a id="function-bind:MANY_BIND"></a>

### `bind( bindProperties ) → ObservableMultiBindChain` _(inherited)_

Binds [observable properties](#function-set:KEY_VALUE) to other objects implementing the [`Observable`](module_utils_observablemixin-Observable.md) interface.

Read more in the [dedicated](../framework/deep-dive/observables.md#property-bindings) guide covering the topic of property bindings with some additional examples.

Consider two objects: a `button` and an associated `command` (both `Observable`).

A simple property binding could be as follows:

```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled' );
```

or even shorter:

```typescript
button.bind( 'isEnabled' ).to( command );
```

which works in the following way:

* `button.isEnabled` **instantly equals** `command.isEnabled`,
* whenever `command.isEnabled` changes, `button.isEnabled` will immediately reflect its value.

**Note**: To release the binding, use [`unbind`](module_utils_observablemixin-Observable.md#function-unbind).

You can also "rename" the property in the binding by specifying the new name in the `to()` chain:

```typescript
button.bind( 'isEnabled' ).to( command, 'isWorking' );
```

It is possible to bind more than one property at a time to shorten the code:

```typescript
button.bind( 'isEnabled', 'value' ).to( command );
```

which corresponds to:

```typescript
button.bind( 'isEnabled' ).to( command );
button.bind( 'value' ).to( command );
```

The binding can include more than one observable, combining multiple data sources in a custom callback:

```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible',
	( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible );
```

Using a custom callback allows processing the value before passing it to the target property:

```typescript
button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );
```

It is also possible to bind to the same property in an array of observables. To bind a `button` to multiple commands (also `Observables`) so that each and every one of them must be enabled for the button to become enabled, use the following code:

```typescript
button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
	( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
```

#### Parameters

* `bindProperties: Array<'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'destroy' | 'init' | 'afterInit' | 'editor' | 'isEnabled' | 'forceDisabled' | 'clearForceDisabled' | 'process' | 'makeSnapshot' | 'computePatch' | 'applyPatch' | 'computeChanges' | 'applyChange'>`

  Observable properties that will be bound to other observable(s).

#### Returns

* `ObservableMultiBindChain`

  The bind chain with the `to()` and `toMany()` methods.

<a id="function-bind:SINGLE_BIND"></a>

### `bind( bindProperty ) → ObservableSingleBindChain<K, DocumentCompare[ K ]>` _(inherited)_

Binds [observable properties](#function-set:KEY_VALUE) to other objects implementing the [`Observable`](module_utils_observablemixin-Observable.md) interface.

Read more in the [dedicated](../framework/deep-dive/observables.md#property-bindings) guide covering the topic of property bindings with some additional examples.

Consider two objects: a `button` and an associated `command` (both `Observable`).

A simple property binding could be as follows:

```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled' );
```

or even shorter:

```typescript
button.bind( 'isEnabled' ).to( command );
```

which works in the following way:

* `button.isEnabled` **instantly equals** `command.isEnabled`,
* whenever `command.isEnabled` changes, `button.isEnabled` will immediately reflect its value.

**Note**: To release the binding, use [`unbind`](module_utils_observablemixin-Observable.md#function-unbind).

You can also "rename" the property in the binding by specifying the new name in the `to()` chain:

```typescript
button.bind( 'isEnabled' ).to( command, 'isWorking' );
```

It is possible to bind more than one property at a time to shorten the code:

```typescript
button.bind( 'isEnabled', 'value' ).to( command );
```

which corresponds to:

```typescript
button.bind( 'isEnabled' ).to( command );
button.bind( 'value' ).to( command );
```

The binding can include more than one observable, combining multiple data sources in a custom callback:

```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible',
	( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible );
```

Using a custom callback allows processing the value before passing it to the target property:

```typescript
button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );
```

It is also possible to bind to the same property in an array of observables. To bind a `button` to multiple commands (also `Observables`) so that each and every one of them must be enabled for the button to become enabled, use the following code:

```typescript
button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
	( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
```

#### Type parameters

* `K`

#### Parameters

* `bindProperty: K`

  Observable property that will be bound to other observable(s).

#### Returns

* `ObservableSingleBindChain<K, DocumentCompare[ K ]>`

  The bind chain with the `to()` and `toMany()` methods.

<a id="function-clearForceDisabled"></a>

### `clearForceDisabled( id ) → void` _(inherited)_

Clears forced disable previously set through [`forceDisabled`](#function-forceDisabled). See [`forceDisabled`](#function-forceDisabled).

#### Parameters

* `id: string`

  Unique identifier, equal to the one passed in [`forceDisabled`](#function-forceDisabled) call.

#### Returns

* `void`

<a id="function-computeChanges"></a>

### `computeChanges( snapshot, data, options ) → Array<DocumentChange>`

Compares the earlier captured snapshot and the given data. Returns a set of grouped [document changes](module_ai_toolkit_proposedchange-DocumentChange.md). Changes are grouped based on where in the document they sit - related changes made next to each other are put together into one group. Each group is one, atomic, reviewable unit, to be accepted or rejected independently of each other.

The document changes can be collected into a [set of proposed changes](module_ai_toolkit_proposedchangescollection-ProposedChangesCollection.md) and passed to [`createController`](module_ai_toolkit_proposedchanges-ProposedChanges.md#function-createController) to create a controller, which binds the changes with an editor instance and offers an API to operate on them. To provide an interface for managing the changes, [create a proposed changes UI component](module_ai_toolkit_proposedchanges-ProposedChanges.md#function-createView) and [attach](module_ai_toolkit_proposedchangescontrollertype-ProposedChangesController.md#function-attachView) it to the controller.

You can also apply the accepted document changes directly, using [`applyChange`](#function-applyChange).

The passed data is compared against the snapshot state. When a change is accepted, it is resolved against any changes that happened in the editor since the snapshot was taken. This allows you to process the data asynchronously, while retaining any edits that have happened in the editor in the meantime.

If you did not make the snapshot for processing purposes (for example, a case where you compare editor data to a different, already existing document), make the snapshot just before calling `computeChanges()`.

If the processed data for an inline root contains block content, no change is returned for that root and a `documentcompare-unsupported-inline-root-content` warning is logged.

#### Parameters

* `snapshot: DocumentCompareSnapshot`

  The captured before-state to compare against.

* `data: string | Record<string, string>`

  The processed data. For multi-root editor, pass an object keyed by root name.

* `options: DocumentCompareComputeChangesOptions`

  How the comparison is computed.

  Defaults to `{}`

#### Returns

* `Array<DocumentChange>`

  The changes bringing the document from the snapshot to the processed state, in document order.

<a id="function-computePatch"></a>

### `computePatch( snapshot, data, options ) → DocumentComparePatch`

Computes a document patch - a set of granular differences between the earlier captured snapshot and the given data. You can apply the patch using [`applyPatch`](#function-applyPatch). All changes from the patch are applied at once.

Use `options` to set whether the patch should be calculated and applied as tracked changes or as direct changes to the document.

The passed data is compared against the snapshot state. Later, when a patch is applied, the differences are resolved against any changes that happened in the editor since the snapshot was taken. This allows you to process the data asynchronously, while retaining all edits that have happened in the editor in the meantime.

If you did not make the snapshot for processing purposes (for example, a case where you compare editor data to a different, already existing document), make the snapshot just before calling `computePatch()`.

Throws `documentcompare-unsupported-inline-root-content` if the processed data for an inline root contains block content.

#### Parameters

* `snapshot: DocumentCompareSnapshot`

  The captured before-state to diff against.

* `data: string | Record<string, string>`

  The new data. For multi-root editor, pass an object keyed by root name.

* `options: DocumentCompareComputePatchOptions`

  How the comparison is computed.

  Defaults to `{}`

#### Returns

* `DocumentComparePatch`

  The patch bringing the document from the snapshot to the processed state.

<a id="function-decorate"></a>

### `decorate( methodName ) → void` _(inherited)_

Turns the given methods of this object into event-based ones. This means that the new method will fire an event (named after the method) and the original action will be plugged as a listener to that event.

Read more in the [dedicated](../framework/deep-dive/observables.md#decorating-object-methods) guide covering the topic of decorating methods with some additional examples.

Decorating the method does not change its behavior (it only adds an event), but it allows to modify it later on by listening to the method's event.

For example, to cancel the method execution the event can be [stopped](module_utils_eventinfo-EventInfo.md#member-stop):

```typescript
class Foo extends ObservableMixin() {
	constructor() {
		super();
		this.decorate( 'method' );
	}

	method() {
		console.log( 'called!' );
	}
}

const foo = new Foo();
foo.on( 'method', ( evt ) => {
	evt.stop();
}, { priority: 'high' } );

foo.method(); // Nothing is logged.
```

**Note**: The high [priority](module_utils_priorities-PriorityString.md) listener has been used to execute this particular callback before the one which calls the original method (which uses the "normal" priority).

It is also possible to change the returned value:

```typescript
foo.on( 'method', ( evt ) => {
	evt.return = 'Foo!';
} );

foo.method(); // -> 'Foo'
```

Finally, it is possible to access and modify the arguments the method is called with:

```typescript
method( a, b ) {
	console.log( `${ a }, ${ b }`  );
}

// ...

foo.on( 'method', ( evt, args ) => {
	args[ 0 ] = 3;

	console.log( args[ 1 ] ); // -> 2
}, { priority: 'high' } );

foo.method( 1, 2 ); // -> '3, 2'
```

#### Parameters

* `methodName: 'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'destroy' | 'init' | 'afterInit' | 'editor' | 'isEnabled' | 'forceDisabled' | 'clearForceDisabled' | 'process' | 'makeSnapshot' | 'computePatch' | 'applyPatch' | 'computeChanges' | 'applyChange'`

  Name of the method to decorate.

#### Returns

* `void`

<a id="function-delegate"></a>

### `delegate( events ) → EmitterMixinDelegateChain` _(inherited)_

Delegates selected events to another [`Emitter`](module_utils_emittermixin-Emitter.md). For instance:

```typescript
emitterA.delegate( 'eventX' ).to( emitterB );
emitterA.delegate( 'eventX', 'eventY' ).to( emitterC );
```

then `eventX` is delegated (fired by) `emitterB` and `emitterC` along with `data`:

```typescript
emitterA.fire( 'eventX', data );
```

and `eventY` is delegated (fired by) `emitterC` along with `data`:

```typescript
emitterA.fire( 'eventY', data );
```

#### Parameters

* `events: Array<string>`

  Event names that will be delegated to another emitter.

#### Returns

* `EmitterMixinDelegateChain`

<a id="function-destroy"></a>

### `destroy() → void` _(inherited)_

Destroys the plugin.

**Note:** This method is optional. A plugin instance does not need to have it defined.

#### Returns

* `void`

<a id="function-fire"></a>

### `fire( eventOrInfo, args ) → GetEventInfo<TEvent>[ 'return' ]` _(inherited)_

Fires an event, executing all callbacks registered for it.

The first parameter passed to callbacks is an [`EventInfo`](module_utils_eventinfo-EventInfo.md) object, followed by the optional `args` provided in the `fire()` method call.

#### Type parameters

* `TEvent: extends BaseEvent`

  The type describing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md).

#### Parameters

* `eventOrInfo: GetNameOrEventInfo<TEvent>`

  The name of the event or `EventInfo` object if event is delegated.

* `args: TEvent[ 'args' ]`

  Additional arguments to be passed to the callbacks.

#### Returns

* `GetEventInfo<TEvent>[ 'return' ]`

  By default the method returns `undefined`. However, the return value can be changed by listeners through modification of the [`evt.return`](module_utils_eventinfo-EventInfo.md#member-return)'s property (the event info is the first param of every callback).

<a id="function-forceDisabled"></a>

### `forceDisabled( id ) → void` _(inherited)_

Disables the plugin.

Plugin may be disabled by multiple features or algorithms (at once). When disabling a plugin, unique id should be passed (e.g. feature name). The same identifier should be used when [enabling back](#function-clearForceDisabled) the plugin. The plugin becomes enabled only after all features [enabled it back](#function-clearForceDisabled).

Disabling and enabling a plugin:

```typescript
plugin.isEnabled; // -> true
plugin.forceDisabled( 'MyFeature' );
plugin.isEnabled; // -> false
plugin.clearForceDisabled( 'MyFeature' );
plugin.isEnabled; // -> true
```

Plugin disabled by multiple features:

```typescript
plugin.forceDisabled( 'MyFeature' );
plugin.forceDisabled( 'OtherFeature' );
plugin.clearForceDisabled( 'MyFeature' );
plugin.isEnabled; // -> false
plugin.clearForceDisabled( 'OtherFeature' );
plugin.isEnabled; // -> true
```

Multiple disabling with the same identifier is redundant:

```typescript
plugin.forceDisabled( 'MyFeature' );
plugin.forceDisabled( 'MyFeature' );
plugin.clearForceDisabled( 'MyFeature' );
plugin.isEnabled; // -> true
```

**Note:** some plugins or algorithms may have more complex logic when it comes to enabling or disabling certain plugins, so the plugin might be still disabled after [`clearForceDisabled`](#function-clearForceDisabled) was used.

#### Parameters

* `id: string`

  Unique identifier for disabling. Use the same id when [enabling back](#function-clearForceDisabled) the plugin.

#### Returns

* `void`

<a id="function-init"></a>

### `init() → void`

#### Returns

* `void`

<a id="function-listenTo:BASE_EMITTER"></a>

### `listenTo( emitter, event, callback, options? ) → void` _(inherited)_

Registers a callback function to be executed when an event is fired in a specific (emitter) object.

Events can be grouped in namespaces using `:`. When namespaced event is fired, it additionally fires all callbacks for that namespace.

```typescript
// myEmitter.on( ... ) is a shorthand for myEmitter.listenTo( myEmitter, ... ).
myEmitter.on( 'myGroup', genericCallback );
myEmitter.on( 'myGroup:myEvent', specificCallback );

// genericCallback is fired.
myEmitter.fire( 'myGroup' );
// both genericCallback and specificCallback are fired.
myEmitter.fire( 'myGroup:myEvent' );
// genericCallback is fired even though there are no callbacks for "foo".
myEmitter.fire( 'myGroup:foo' );
```

An event callback can [stop the event](module_utils_eventinfo-EventInfo.md#member-stop) and set the [return value](module_utils_eventinfo-EventInfo.md#member-return) of the [`fire`](#function-fire) method.

#### Type parameters

* `TEvent: extends BaseEvent`

  The type describing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md).

#### Parameters

* `emitter: Emitter`

  The object that fires the event.

* `event: TEvent[ 'name' ]`

  The name of the event.

* `callback: GetCallback<TEvent>`

  The function to be called on event.

* `options?: GetCallbackOptions<TEvent>`

  Additional options.

#### Returns

* `void`

<a id="function-makeSnapshot"></a>

### `makeSnapshot( options ) → DocumentCompareSnapshot`

Captures the current document state as a [`DocumentCompareSnapshot`](module_ai_toolkit_documentsnapshot-DocumentCompareSnapshot.md).

The snapshot contains all data and metadata necessary to process the document and then be able to calculate differences between the original and the processed data.

Importantly, `snapshot.content` holds data for each root (excluding `$graveyard`), serialized to HTML. By default, the data is stamped with `data-id` attributes, assigned to structural elements of the data. During processing, make sure that these `data-id`s are retained. They are used to identify which elements were kept, which were removed, and which are new.

If the processing cannot retain them, capture the snapshot without the ids ([`options.useDataIds: false`](module_ai_toolkit_documentcompare-DocumentCompareSnapshotOptions.md#member-useDataIds)). When data IDs are skipped, the original and processed data is compared only by the content similarity.

The content of an inline root is wrapped in a single, artificial `<p data-id="...">` element. This wrapper always gets a `data-id`, even when the snapshot is captured with `options.useDataIds: false`. Process only the content inside the wrapper.

See also [`DocumentCompareSnapshot`](module_ai_toolkit_documentsnapshot-DocumentCompareSnapshot.md).

#### Parameters

* `options: DocumentCompareSnapshotOptions`

  How the snapshot is captured.

  Defaults to `{}`

#### Returns

* `DocumentCompareSnapshot`

  The captured snapshot.

<a id="function-off"></a>

### `off( event, callback ) → void` _(inherited)_

Stops executing the callback on the given event. Shorthand for [`this.stopListening( this, event, callback )`](#function-stopListening:BASE_STOP).

#### Parameters

* `event: string`

  The name of the event.

* `callback: Function`

  The function to stop being called.

#### Returns

* `void`

<a id="function-on"></a>

### `on( event, callback, options? ) → void` _(inherited)_

Registers a callback function to be executed when an event is fired.

Shorthand for [`this.listenTo( this, event, callback, options )`](#function-listenTo:BASE_EMITTER) (it makes the emitter listen on itself).

#### Type parameters

* `TEvent: extends BaseEvent`

  The type descibing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md).

#### Parameters

* `event: TEvent[ 'name' ]`

  The name of the event.

* `callback: GetCallback<TEvent>`

  The function to be called on event.

* `options?: GetCallbackOptions<TEvent>`

  Additional options.

#### Returns

* `void`

<a id="function-once"></a>

### `once( event, callback, options? ) → void` _(inherited)_

Registers a callback function to be executed on the next time the event is fired only. This is similar to calling [`on`](#function-on) followed by [`off`](#function-off) in the callback.

#### Type parameters

* `TEvent: extends BaseEvent`

  The type descibing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md).

#### Parameters

* `event: TEvent[ 'name' ]`

  The name of the event.

* `callback: GetCallback<TEvent>`

  The function to be called on event.

* `options?: GetCallbackOptions<TEvent>`

  Additional options.

#### Returns

* `void`

<a id="function-process"></a>

### `process( callback, options ) → Promise<boolean>`

Runs the whole processing pipeline in one call: snapshots the document, hands the snapshot to `callback` for external processing (e.g. an AI service), then diffs returned data and applies granular changes to the document.

This is a "shortcut" for using [`makeSnapshot`](#function-makeSnapshot), [`computePatch`](#function-computePatch), and [`applyPatch`](#function-applyPatch).

If diffing or applying fails, the underlying error is rethrown and can be further handled, unless `options.overwriteOnError` is set, in which case the current document is instead fully replaced with the processed data, the same way as if `editor.setData()` was used. In this case, changes that happened to the document after the snapshot was taken will be overwritten. See [`overwriteOnError`](module_ai_toolkit_documentcompare-DocumentCompareProcessOptions.md#member-overwriteOnError) for the side effects of the replacement.

Errors thrown or rejected by `callback` are always rethrown, regardless of `options.overwriteOnError`.

The snapshot is captured with data IDs stamped on the document content, unless `options.useDataIds` is `false`. See [`useDataIds`](module_ai_toolkit_documentcompare-DocumentCompareSnapshotOptions.md#member-useDataIds).

#### Parameters

* `callback: ( snapshot: DocumentCompareSnapshot ) => Promise<string | Record<string, string>>`

  Receives the captured snapshot and returns the processed data. For multi-root editor, return an object keyed by root name. Otherwise, return a string with the data of the main root.

* `options: DocumentCompareProcessOptions`

  Additional processing options.

  Defaults to `{}`

#### Returns

* `Promise<boolean>`

  `true` when the process finished successfully and changes were applied granularly, `false` when the full-replacement fallback was used.

<a id="function-set:OBJECT"></a>

### `set( values ) → void` _(inherited)_

Creates and sets the value of an observable properties of this object. Such a property becomes a part of the state and is observable.

It accepts a single object literal containing key/value pairs with properties to be set.

This method throws the `observable-set-cannot-override` error if the observable instance already has a property with the given property name. This prevents from mistakenly overriding existing properties and methods, but means that `foo.set( 'bar', 1 )` may be slightly slower than `foo.bar = 1`.

In TypeScript, those properties should be declared in class using `declare` keyword. In example:

```typescript
public declare myProp1: number;
public declare myProp2: string;

constructor() {
	this.set( {
		'myProp1: 2,
		'myProp2: 'foo'
	} );
}
```

#### Parameters

* `values: object & object`

  An object with `name=>value` pairs.

#### Returns

* `void`

<a id="function-set:KEY_VALUE"></a>

### `set( name, value ) → void` _(inherited)_

Creates and sets the value of an observable property of this object. Such a property becomes a part of the state and is observable.

This method throws the `observable-set-cannot-override` error if the observable instance already has a property with the given property name. This prevents from mistakenly overriding existing properties and methods, but means that `foo.set( 'bar', 1 )` may be slightly slower than `foo.bar = 1`.

In TypeScript, those properties should be declared in class using `declare` keyword. In example:

```typescript
public declare myProp: number;

constructor() {
	this.set( 'myProp', 2 );
}
```

#### Type parameters

* `K`

#### Parameters

* `name: K`

  The property's name.

* `value: DocumentCompare[ K ]`

  The property's value.

#### Returns

* `void`

<a id="function-stopDelegating"></a>

### `stopDelegating( event?, emitter? ) → void` _(inherited)_

Stops delegating events. It can be used at different levels:

* To stop delegating all events.
* To stop delegating a specific event to all emitters.
* To stop delegating a specific event to a specific emitter.

#### Parameters

* `event?: string`

  The name of the event to stop delegating. If omitted, stops it all delegations.

* `emitter?: Emitter`

  (requires `event`) The object to stop delegating a particular event to. If omitted, stops delegation of `event` to all emitters.

#### Returns

* `void`

<a id="function-stopListening:BASE_STOP"></a>

### `stopListening( emitter?, event?, callback? ) → void` _(inherited)_

Stops listening for events. It can be used at different levels:

* To stop listening to a specific callback.
* To stop listening to a specific event.
* To stop listening to all events fired by a specific object.
* To stop listening to all events fired by all objects.

#### Parameters

* `emitter?: Emitter`

  The object to stop listening to. If omitted, stops it for all objects.

* `event?: string`

  (Requires the `emitter`) The name of the event to stop listening to. If omitted, stops it for all events from `emitter`.

* `callback?: Function`

  (Requires the `event`) The function to be removed from the call list for the given `event`.

#### Returns

* `void`

<a id="function-unbind"></a>

### `unbind( unbindProperties ) → void` _(inherited)_

Removes the binding created with [`bind`](#function-bind:SINGLE_BIND).

```typescript
// Removes the binding for the 'a' property.
A.unbind( 'a' );

// Removes bindings for all properties.
A.unbind();
```

#### Parameters

* `unbindProperties: Array<'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'destroy' | 'init' | 'afterInit' | 'editor' | 'isEnabled' | 'forceDisabled' | 'clearForceDisabled' | 'process' | 'makeSnapshot' | 'computePatch' | 'applyPatch' | 'computeChanges' | 'applyChange'>`

  Observable properties to be unbound. All the bindings will be released if no properties are provided.

#### Returns

* `void`

<a id="events"></a>

## Events

<a id="event-change:isEnabled"></a>

### `change:isEnabled( eventInfo, name, value, oldValue )` _(inherited)_

Fired when the `isEnabled` property changed value.

#### Parameters

* `eventInfo: EventInfo`

  An object containing information about the fired event.

* `name: string`

  Name of the changed property (`isEnabled`).

* `value: boolean`

  New value of the `isEnabled` property with given key or `null`, if operation should remove property.

* `oldValue: boolean`

  Old value of the `isEnabled` property with given key or `null`, if property was not set before.

<a id="event-change:%7Bproperty%7D"></a>

### `change:{property}( eventInfo, name, value, oldValue )` _(inherited)_

Fired when a property changed value.

```typescript
observable.set( 'prop', 1 );

observable.on<ObservableChangeEvent<number>>( 'change:prop', ( evt, propertyName, newValue, oldValue ) => {
	console.log( `${ propertyName } has changed from ${ oldValue } to ${ newValue }` );
} );

observable.prop = 2; // -> 'prop has changed from 1 to 2'
```

#### Parameters

* `eventInfo: EventInfo`

  An object containing information about the fired event.

* `name: string`

  The property name.

* `value: TValue`

  The new property value.

* `oldValue: TValue`

  The previous property value.

<a id="event-set:isEnabled"></a>

### `set:isEnabled( eventInfo, name, value, oldValue )` _(inherited)_

Fired when the `isEnabled` property is going to be set but is not set yet (before the `change` event is fired).

#### Parameters

* `eventInfo: EventInfo`

  An object containing information about the fired event.

* `name: string`

  Name of the changed property (`isEnabled`).

* `value: boolean`

  New value of the `isEnabled` property with given key or `null`, if operation should remove property.

* `oldValue: boolean`

  Old value of the `isEnabled` property with given key or `null`, if property was not set before.

<a id="event-set:%7Bproperty%7D"></a>

### `set:{property}( eventInfo, name, value, oldValue )` _(inherited)_

Fired when a property value is going to be set but is not set yet (before the `change` event is fired).

You can control the final value of the property by using the [event's `return` property](module_utils_eventinfo-EventInfo.md#member-return).

```typescript
observable.set( 'prop', 1 );

observable.on<ObservableSetEvent<number>>( 'set:prop', ( evt, propertyName, newValue, oldValue ) => {
	console.log( `Value is going to be changed from ${ oldValue } to ${ newValue }` );
	console.log( `Current property value is ${ observable[ propertyName ] }` );

	// Let's override the value.
	evt.return = 3;
} );

observable.on<ObservableChangeEvent<number>>( 'change:prop', ( evt, propertyName, newValue, oldValue ) => {
	console.log( `Value has changed from ${ oldValue } to ${ newValue }` );
} );

observable.prop = 2; // -> 'Value is going to be changed from 1 to 2'
					 // -> 'Current property value is 1'
					 // -> 'Value has changed from 1 to 3'
```

**Note:** The event is fired even when the new value is the same as the old value.

#### Parameters

* `eventInfo: EventInfo`

  An object containing information about the fired event.

* `name: string`

  The property name.

* `value: TValue`

  The new property value.

* `oldValue: TValue`

  The previous property value.

---

Full index of the CKEditor 5 API reference: [llms.txt](llms.txt)