Emitter
Emitter/listener interface.
Can be easily implemented by a class by mixing the Emitter mixin.
class MyClass extends EmitterMixin() {
// This class now implements the `Emitter` interface.
}
Read more about the usage of this interface in the:
- Event system and observables section of the Core editor architecture guide.
- Event system deep-dive guide.
Methods
delegate( events ) → EmitterMixinDelegateChainmodule:utils/emittermixin~Emitter#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
fire( eventOrInfo, args ) → GetEventInfo<TEvent>[ 'return' ]module:utils/emittermixin~Emitter#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
TEvent : extends BaseEventThe type describing the event. See
BaseEvent.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).
listenTo( emitter, event, callback, [ options ] ) → voidmodule:utils/emittermixin~Emitter#listenTo:BASE_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
TEvent : extends BaseEventThe type describing the event. See
BaseEvent.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 ] : GetCallbackOptions<TEvent>Additional options.
Returns
void
off( event, callback ) → voidmodule:utils/emittermixin~Emitter#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
on( event, callback, [ options ] ) → voidmodule:utils/emittermixin~Emitter#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
TEvent : extends BaseEventThe type descibing the event. See
BaseEvent.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
once( event, callback, [ options ] ) → voidmodule:utils/emittermixin~Emitter#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
TEvent : extends BaseEventThe type descibing the event. See
BaseEvent.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 ] ) → voidmodule:utils/emittermixin~Emitter#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
stopListening( [ emitter ], [ event ], [ callback ] ) → voidmodule:utils/emittermixin~Emitter#stopListening:BASE_STOPStops 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 ] : 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