Interface Emitter

Emitter/listener interface.

Can be easily implemented by a class by mixing the module:utils/emittermixin~Emitter mixin.

class MyClass extends EmitterMixin() {
	// This class now implements the `Emitter` interface.
}

Read more about the usage of this interface in the:

{@glink framework/architecture/core-editor-architecture#event-system-and-observables Event system and observables} section of the {@glink framework/architecture/core-editor-architecture Core editor architecture} guide.
{@glink framework/deep-dive/event-system Event system} deep-dive guide.

interface Emitter {
    delegate(...events: string[]): EmitterMixinDelegateChain;
    fire<TEvent extends BaseEvent>(
        eventOrInfo: GetNameOrEventInfo<TEvent>,
        ...args: TEvent["args"],
    ): GetEventInfo<TEvent>["return"];
    listenTo<TEvent extends BaseEvent>(
        emitter: Emitter,
        event: TEvent["name"],
        callback: GetCallback<TEvent>,
        options?: GetCallbackOptions<TEvent>,
    ): void;
    off(event: string, callback: Function): void;
    on<TEvent extends BaseEvent>(
        event: TEvent["name"],
        callback: GetCallback<TEvent>,
        options?: GetCallbackOptions<TEvent>,
    ): void;
    once<TEvent extends BaseEvent>(
        event: TEvent["name"],
        callback: GetCallback<TEvent>,
        options?: GetCallbackOptions<TEvent>,
    ): void;
    stopDelegating(event?: string, emitter?: Emitter): void;
    stopListening(emitter?: Emitter, event?: string, callback?: Function): void;
}

Hierarchy (View Summary)

Emitter
- Observable
- DomEmitter

Index

Methods

delegate fire listenTo off on once stopDelegating stopListening

Methods

delegate

delegate(...events: string[]): EmitterMixinDelegateChain
Delegates selected events to another module:utils/emittermixin~Emitter. For instance:
```
emitterA.delegate( 'eventX' ).to( emitterB );
emitterA.delegate( 'eventX', 'eventY' ).to( emitterC );
```
then eventX is delegated (fired by) emitterB and emitterC along with data:
```
emitterA.fire( 'eventX', data );
```
and eventY is delegated (fired by) emitterC along with data:
```
emitterA.fire( 'eventY', data );
```
Parameters
- ...events: string[]
  Event names that will be delegated to another emitter.
Returns EmitterMixinDelegateChain
- Defined in node_modules/@ckeditor/ckeditor5-utils/src/emittermixin.d.ts:184

fire

fire<TEvent extends BaseEvent>(
eventOrInfo: GetNameOrEventInfo<TEvent>,
...args: TEvent["args"],
): GetEventInfo<TEvent>["return"]
Fires an event, executing all callbacks registered for it.

The first parameter passed to callbacks is an module:utils/eventinfo~EventInfo object, followed by the optional args provided in the fire() method call.
Type Parameters
- TEvent extends BaseEvent
  The type describing the event. See module:utils/emittermixin~BaseEvent.
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 module:utils/eventinfo~EventInfo#return evt.return's property (the event info is the first param of every callback).
- Defined in node_modules/@ckeditor/ckeditor5-utils/src/emittermixin.d.ts:161

listenTo

listenTo<TEvent extends BaseEvent>(
    emitter: Emitter,
    event: TEvent["name"],
    callback: GetCallback<TEvent>,
    options?: GetCallbackOptions<TEvent>,
): void
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.
```
// 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 module:utils/eventinfo~EventInfo#stop stop the event and set the module:utils/eventinfo~EventInfo#return return value of the #fire method.
Type Parameters
- TEvent extends BaseEvent
  The type describing the event. See module:utils/emittermixin~BaseEvent.
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.
- Optionaloptions: GetCallbackOptions<TEvent>
  Additional options.
Returns void
Label
BASE_EMITTER
- Defined in node_modules/@ckeditor/ckeditor5-utils/src/emittermixin.d.ts:131

off

off(event: string, callback: Function): void
Stops executing the callback on the given event. Shorthand for #stopListening this.stopListening( this, event, callback ).
Parameters
- event: string
  The name of the event.
- callback: Function
  The function to stop being called.
Returns void
- Defined in node_modules/@ckeditor/ckeditor5-utils/src/emittermixin.d.ts:101

on

on<TEvent extends BaseEvent>(
    event: TEvent["name"],
    callback: GetCallback<TEvent>,
    options?: GetCallbackOptions<TEvent>,
): void
Registers a callback function to be executed when an event is fired.

Shorthand for #listenTo this.listenTo( this, event, callback, options ) (it makes the emitter listen on itself).
Type Parameters
- TEvent extends BaseEvent
  The type descibing the event. See module:utils/emittermixin~BaseEvent.
Parameters
- event: TEvent["name"]
  The name of the event.
- callback: GetCallback<TEvent>
  The function to be called on event.
- Optionaloptions: GetCallbackOptions<TEvent>
  Additional options.
Returns void
- Defined in node_modules/@ckeditor/ckeditor5-utils/src/emittermixin.d.ts:83

once

once<TEvent extends BaseEvent>(
    event: TEvent["name"],
    callback: GetCallback<TEvent>,
    options?: GetCallbackOptions<TEvent>,
): void
Registers a callback function to be executed on the next time the event is fired only. This is similar to calling #on followed by #off in the callback.
Type Parameters
- TEvent extends BaseEvent
  The type descibing the event. See module:utils/emittermixin~BaseEvent.
Parameters
- event: TEvent["name"]
  The name of the event.
- callback: GetCallback<TEvent>
  The function to be called on event.
- Optionaloptions: GetCallbackOptions<TEvent>
  Additional options.
Returns void
- Defined in node_modules/@ckeditor/ckeditor5-utils/src/emittermixin.d.ts:93

stopDelegating

stopDelegating(event?: string, emitter?: Emitter): void
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
- Optionalevent: string
  The name of the event to stop delegating. If omitted, stops it all delegations.
- Optionalemitter: Emitter
  (requires event) The object to stop delegating a particular event to. If omitted, stops delegation of event to all emitters.
Returns void
- Defined in node_modules/@ckeditor/ckeditor5-utils/src/emittermixin.d.ts:196

stopListening

stopListening(emitter?: Emitter, event?: string, callback?: Function): void
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
- Optionalemitter: Emitter
  The object to stop listening to. If omitted, stops it for all objects.
- Optionalevent: string
  (Requires the emitter) The name of the event to stop listening to. If omitted, stops it for all events from emitter.
- Optionalcallback: Function
  (Requires the event) The function to be removed from the call list for the given event.
Returns void
Label
BASE_STOP
- Defined in node_modules/@ckeditor/ckeditor5-utils/src/emittermixin.d.ts:147

Interface Emitter

Hierarchy (View Summary)

Index

Methods

Methods

delegate

Parameters

Returns EmitterMixinDelegateChain

fire

Type Parameters

Parameters

Returns GetEventInfo<TEvent>["return"]

listenTo

Type Parameters

Parameters

Returns void

Label

off

Parameters

Returns void

on

Type Parameters

Parameters

Returns void

once

Type Parameters

Parameters

Returns void

stopDelegating

Parameters

Returns void

stopListening

Parameters

Returns void

Label

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