MutationObserver
Mutation observer's role is to watch for any DOM changes inside the editor that weren't
done by the editor's ViewRenderer itself and reverting these changes.
It does this by observing all mutations in the DOM, marking related view elements as changed and calling
render. Because all mutated nodes are marked as
"to be rendered" and the render() method is called,
all changes are reverted in the DOM (the DOM is synced with the editor's view structure).
Note that this observer is attached by the EditingView and is available by default.
Properties
-
document : ViewDocumentreadonlyinheritedmodule:engine/view/observer/mutationobserver~MutationObserver#documentA reference to the
ViewDocumentobject. -
domConverter : ViewDomConverterreadonlymodule:engine/view/observer/mutationobserver~MutationObserver#domConverterReference to the
domConverter. -
isEnabled : booleanreadonlyinheritedmodule:engine/view/observer/mutationobserver~MutationObserver#isEnabledThe state of the observer. If it is disabled, no events will be fired.
-
view : EditingViewreadonlyinheritedmodule:engine/view/observer/mutationobserver~MutationObserver#viewAn instance of the view controller.
-
_config : MutationObserverInitprivatereadonlymodule:engine/view/observer/mutationobserver~MutationObserver#_configNative mutation observer config.
-
_domElements : Set<HTMLElement>privatereadonlymodule:engine/view/observer/mutationobserver~MutationObserver#_domElementsObserved DOM elements.
-
_mutationObserver : MutationObserverprivatemodule:engine/view/observer/mutationobserver~MutationObserver#_mutationObserverNative mutation observer.
Methods
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constructor( view )module:engine/view/observer/mutationobserver~MutationObserver#constructor -
checkShouldIgnoreEventFromTarget( domTarget ) → booleaninheritedmodule:engine/view/observer/mutationobserver~MutationObserver#checkShouldIgnoreEventFromTargetChecks whether a given DOM event should be ignored (should not be turned into a synthetic view document event).
Currently, an event will be ignored only if its target or any of its ancestors has the
data-cke-ignore-eventsattribute. This attribute can be used inside the structures generated byViewDowncastWriter#createUIElement()to ignore events fired within a UI that should be excluded from CKEditor 5's realms.Parameters
domTarget : null | NodeThe DOM event target to check (usually an element, sometimes a text node and potentially sometimes a document, too).
Returns
booleanWhether this event should be ignored by the observer.
-
delegate( events ) → EmitterMixinDelegateChaininheritedmodule:engine/view/observer/mutationobserver~MutationObserver#delegateDelegates selected events to another
Emitter. For instance:emitterA.delegate( 'eventX' ).to( emitterB ); emitterA.delegate( 'eventX', 'eventY' ).to( emitterC );Copy codethen
eventXis delegated (fired by)emitterBandemitterCalong withdata:emitterA.fire( 'eventX', data );Copy codeand
eventYis delegated (fired by)emitterCalong withdata:emitterA.fire( 'eventY', data );Copy codeParameters
events : Array<string>Event names that will be delegated to another emitter.
Returns
-
destroy() → voidmodule:engine/view/observer/mutationobserver~MutationObserver#destroyDisables and destroys the observer, among others removes event listeners created by the observer.
Returns
void
-
disable() → voidmodule:engine/view/observer/mutationobserver~MutationObserver#disableDisables the observer. This method is called before rendering to prevent firing events during rendering.
Returns
void
Related:
-
enable() → voidmodule:engine/view/observer/mutationobserver~MutationObserver#enableEnables the observer. This method is called when the observer is registered to the
EditingViewand after rendering (all observers are disabled before rendering).A typical use case for disabling observers is that mutation observers need to be disabled for the rendering. However, a child class may not need to be disabled, so it can implement an empty method.
Returns
void
Related:
-
fire( eventOrInfo, args ) → GetEventInfo<TEvent>[ 'return' ]inheritedmodule:engine/view/observer/mutationobserver~MutationObserver#fireFires an event, executing all callbacks registered for it.
The first parameter passed to callbacks is an
EventInfoobject, followed by the optionalargsprovided in thefire()method call.Type parameters
Parameters
eventOrInfo : GetNameOrEventInfo<TEvent>The name of the event or
EventInfoobject 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 theevt.return's property (the event info is the first param of every callback).
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flush() → voidmodule:engine/view/observer/mutationobserver~MutationObserver#flush -
listenTo( emitter, event, callback, [ options ] ) → voidinheritedmodule:engine/view/observer/mutationobserver~MutationObserver#listenTo:DOM_EMITTERRegisters 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.// 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' );Copy codeAn event callback can stop the event and set the return value of the
firemethod.Type parameters
Parameters
emitter : EmitterThe object that fires the event.
event : TEvent[ 'name' ]The name of the event.
callback : GetCallback<TEvent>The function to be called on event.
[ options ] : CallbackOptionsAdditional options.
Returns
void
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listenTo( emitter, event, callback, [ options ] ) → voidinheritedmodule:engine/view/observer/mutationobserver~MutationObserver#listenTo:HTML_EMITTERRegisters a callback function to be executed when an event is fired in a specific Emitter or DOM Node. It is backwards compatible with
listenTo.Type parameters
K : extends keyof DomEventMap
Parameters
emitter : Window | EventTarget | NodeThe object that fires the event.
event : KThe name of the event.
callback : ( this: this, ev: EventInfo, event: DomEventMap[ K ] ) => voidThe function to be called on event.
[ options ] : objectAdditional options.
Returns
void
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observe( domElement ) → voidmodule:engine/view/observer/mutationobserver~MutationObserver#observeStarts observing given DOM element.
Parameters
domElement : HTMLElementDOM element to observe.
Returns
void
-
off( event, callback ) → voidinheritedmodule:engine/view/observer/mutationobserver~MutationObserver#offStops executing the callback on the given event. Shorthand for
this.stopListening( this, event, callback ).Parameters
event : stringThe name of the event.
callback : FunctionThe function to stop being called.
Returns
void
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on( event, callback, [ options ] ) → voidinheritedmodule:engine/view/observer/mutationobserver~MutationObserver#onRegisters a callback function to be executed when an event is fired.
Shorthand for
this.listenTo( this, event, callback, options )(it makes the emitter listen on itself).Type parameters
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
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once( event, callback, [ options ] ) → voidinheritedmodule:engine/view/observer/mutationobserver~MutationObserver#onceRegisters a callback function to be executed on the next time the event is fired only. This is similar to calling
onfollowed byoffin the callback.Type parameters
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
-
stopDelegating( [ event ], [ emitter ] ) → voidinheritedmodule:engine/view/observer/mutationobserver~MutationObserver#stopDelegatingStops 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 ] : stringThe 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 ofeventto all emitters.
Returns
void
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stopListening( [ emitter ], [ event ], [ callback ] ) → voidinheritedmodule:engine/view/observer/mutationobserver~MutationObserver#stopListening:DOM_STOPStops listening for events. It can be used at different levels: It is backwards compatible with
listenTo.- 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 ] : Window | EventTarget | Node | EmitterThe 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 fromemitter.[ callback ] : Function(Requires the
event) The function to be removed from the call list for the givenevent.
Returns
void
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stopObserving( domElement ) → voidmodule:engine/view/observer/mutationobserver~MutationObserver#stopObservingStops observing given DOM element.
Parameters
domElement : HTMLElement
Returns
void
-
_isBogusBrMutation( mutation ) → null | booleanprivatemodule:engine/view/observer/mutationobserver~MutationObserver#_isBogusBrMutationChecks if mutation was generated by the browser inserting bogus br on the end of the block element. Such mutations are generated while pressing space or performing native spellchecker correction on the end of the block element in Firefox browser.
Parameters
mutation : MutationRecordNative mutation object.
Returns
null | boolean
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_onMutations( domMutations ) → voidprivatemodule:engine/view/observer/mutationobserver~MutationObserver#_onMutationsHandles mutations. Mark view elements to sync and call render.
Parameters
domMutations : Array<MutationRecord>Array of native mutations.
Returns
void