EventEmitter

open external class EventEmitter(source)

The EventEmitter class is defined and exposed by the node:events module:

import { EventEmitter } from 'node:events';

All EventEmitters emit the event 'newListener' when new listeners are added and 'removeListener' when existing listeners are removed.

It supports the following option:

Since

v0.1.26

Inheritors

EventEmitterAsyncResource

Constructors

EventEmitter

constructor(options: EventEmitterOptions = definedExternally)

Types

Companion

object Companion

Functions

addListener

fun addListener(type: EventType, listener: EventListener)

Alias for emitter.on(eventName, listener).

emit

fun emit(type: EventType, vararg args: Any?): Boolean

Synchronously calls each of the listeners registered for the event named eventName, in the order they were registered, passing the supplied arguments to each.

eventNames

fun eventNames(): Array<EventType>

Returns an array listing the events for which the emitter has registered listeners. The values in the array are strings or Symbols.

getMaxListeners

fun getMaxListeners(): Double

Returns the current max listener value for the EventEmitter which is either set by emitter.setMaxListeners(n) or defaults to {@link defaultMaxListeners}.

listenerCount

fun listenerCount(type: EventType, listener: EventListener = definedExternally): Double

Returns the number of listeners listening for the event named eventName. If listener is provided, it will return how many times the listener is found in the list of the listeners of the event.

listeners

fun listeners(type: EventType): Array<EventListener>

Returns a copy of the array of listeners for the event named eventName.

off

fun off(type: EventType, listener: EventListener)

Alias for emitter.removeListener().

fun on(type: EventType, listener: EventListener)

Adds the listener function to the end of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.

once

fun once(type: EventType, listener: EventListener)

Adds a one-time listener function for the event named eventName. The next time eventName is triggered, this listener is removed and then invoked.

prependListener

fun prependListener(type: EventType, listener: EventListener)

Adds the listener function to the beginning of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.

prependOnceListener

fun prependOnceListener(type: EventType, listener: EventListener)

Adds a one-timelistener function for the event named eventName to the beginning of the listeners array. The next time eventName is triggered, this listener is removed, and then invoked.

rawListeners

fun rawListeners(type: EventType): Array<EventListener>

Returns a copy of the array of listeners for the event named eventName, including any wrappers (such as those created by .once()).

removeAllListeners

fun removeAllListeners(type: EventType = definedExternally)

Removes all listeners, or those of the specified eventName.

removeListener

fun removeListener(type: EventType, listener: EventListener)

Removes the specified listener from the listener array for the event named eventName.

setMaxListeners

fun setMaxListeners(n: Number)

By default EventEmitters will print a warning if more than 10 listeners are added for a particular event. This is a useful default that helps finding memory leaks. The emitter.setMaxListeners() method allows the limit to be modified for this specific EventEmitter instance. The value can be set to Infinity (or 0) to indicate an unlimited number of listeners.