Emitter¶

Overview¶

Event & listener abstraction for a single "event" type. The type provides extra functionality beyond just notifying listeners. It adds PhET-iO instrumentation capabilities as well as validation. For the lightest-weight, fastest solution with the smallest memory footprint, see TinyEmitter.

@author Sam Reid (PhET Interactive Simulations) @author Michael Kauzmann (PhET Interactive Simulations)

Class Emitter¶

import { Emitter } from 'scenerystack/axon';

Constructor¶

new Emitter( providedOptions? : EmitterOptions )¶

Instance Methods¶

emit( ...args : T )¶

Emit to notify listeners

dispose()¶

Disposes an Emitter. All listeners are removed.

addListener( listener : TEmitterListener<T>, options? : DisposerOptions )¶

Adds a listener which will be called during emit.

removeListener( listener : TEmitterListener<T> )¶

Removes a listener

removeAllListeners()¶

Removes all the listeners

hasListener( listener : TEmitterListener<T> ) : boolean¶

Checks whether a listener is registered with this Emitter

hasListeners() : boolean¶

Returns true if there are any listeners.

getListenerCount() : number¶

Returns the number of listeners.

debug( name : string ) : TEmitterListener<T>¶

Convenience function for debugging a Property's value. It prints the new value on registration and when changed. @param name - debug name to be printed on the console @returns - the handle to the listener added in case it needs to be removed later

Static Properties¶

EmitterIO¶

(readonly)

PhET-iO Type for Emitter.

Providing validators to instrumented Emitters: Instrumented Emitters should have their validators for each argument passed via EmitterIO (the phetioType). To provide validators, there are two methods. First, by default each IOType has its own validator that will be used. So specifying an argument object like { type: NumberIO } will automatically use NumberIO.validator as the validator. This can be overridden with the validator key (second option), like { type: NumberIO, validator: { isValidValue: v=> typeof v === 'number' && v < 5 } }NOTE: currently the implementation is either/or, if a validator is provided via thevalidatorkey, the validator from thetype` will be ignored. see https://github.com/phetsims/axon/issues/204 for more details.

@author Sam Reid (PhET Interactive Simulations) @author Michael Kauzmann (PhET Interactive Simulations) @author Andrew Adare (PhET Interactive Simulations)

Type EmitterOptions¶

import type { EmitterOptions } from 'scenerystack/axon';

Pick<TinyEmitterOptions, "reentrantNotificationStrategy"> & StrictOmit<PhetioDataHandlerOptions, "phetioOuterType">

Source Code¶

See the source for Emitter.ts in the axon repository.