Class MaptilerARControl

StaticcaptureRejections

Static ReadonlycaptureRejectionSymbol

StaticdefaultMaxListeners

import { EventEmitter } from 'node:events';const emitter = new EventEmitter();emitter.setMaxListeners(emitter.getMaxListeners() + 1);emitter.once('event', () => {  // do stuff  emitter.setMaxListeners(Math.max(emitter.getMaxListeners() - 1, 0));});

Static ReadonlyerrorMonitor

Optional[captureRejectionSymbol]

• "[captureRejectionSymbol]"?<K>(
      error: Error,
      event: string | symbol,
      ...args: AnyRest,
  ): void

  Type Parameters

  • K

  Parameters

  • error: Error
  • event: string | symbol
  • ...args: AnyRest

  Returns void

addListener

• addListener<K>(
      eventName: string | symbol,
      listener: (...args: any[]) => void,
  ): this

  Alias for emitter.on(eventName, listener).

  Type Parameters

  • K

  Parameters

  • eventName: string | symbol
  • listener: (...args: any[]) => void

  Returns this

  Since

  v0.1.26

emit

• emit<K>(eventName: string | symbol, ...args: AnyRest): 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.

  Returns true if the event had listeners, false otherwise.

  import { EventEmitter } from 'node:events';const myEmitter = new EventEmitter();// First listenermyEmitter.on('event', function firstListener() {  console.log('Helloooo! first listener');});// Second listenermyEmitter.on('event', function secondListener(arg1, arg2) {  console.log(`event with parameters ${arg1}, ${arg2} in second listener`);});// Third listenermyEmitter.on('event', function thirdListener(...args) {  const parameters = args.join(', ');  console.log(`event with parameters ${parameters} in third listener`);});console.log(myEmitter.listeners('event'));myEmitter.emit('event', 1, 2, 3, 4, 5);// Prints:// [//   [Function: firstListener],//   [Function: secondListener],//   [Function: thirdListener]// ]// Helloooo! first listener// event with parameters 1, 2 in second listener// event with parameters 1, 2, 3, 4, 5 in third listener
  

  Type Parameters

  • K

  Parameters

  • eventName: string | symbol
  • ...args: AnyRest

  Returns boolean

  Since

  v0.1.26

eventNames

• eventNames(): (string | symbol)[]

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

  import { EventEmitter } from 'node:events';const myEE = new EventEmitter();myEE.on('foo', () => {});myEE.on('bar', () => {});const sym = Symbol('symbol');myEE.on(sym, () => {});console.log(myEE.eventNames());// Prints: [ 'foo', 'bar', Symbol(symbol) ]
  

  Returns (string | symbol)[]

  Since

  v6.0.0

getMaxListeners

• getMaxListeners(): number

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

  Returns number

  Since

  v1.0.0

listenerCount

• listenerCount<K>(eventName: string | symbol, listener?: Function): number

  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.

  Type Parameters

  • K

  Parameters

  • eventName: string | symbol

    The name of the event being listened for

  • Optionallistener: Function

    The event handler function

  Returns number

  Since

  v3.2.0

listeners

• listeners<K>(eventName: string | symbol): Function[]

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

  server.on('connection', (stream) => {  console.log('someone connected!');});console.log(util.inspect(server.listeners('connection')));// Prints: [ [Function] ]
  

  Type Parameters

  • K

  Parameters

  • eventName: string | symbol

  Returns Function[]

  Since

  v0.1.26

prependListener

• prependListener<K>(
      eventName: string | symbol,
      listener: (...args: any[]) => void,
  ): this

  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.

  server.prependListener('connection', (stream) => {  console.log('someone connected!');});
  

  Returns a reference to the EventEmitter, so that calls can be chained.

  Type Parameters

  • K

  Parameters

  • eventName: string | symbol

    The name of the event.

  • listener: (...args: any[]) => void

    The callback function

  Returns this

  Since

  v6.0.0

prependOnceListener

• prependOnceListener<K>(
      eventName: string | symbol,
      listener: (...args: any[]) => void,
  ): this

  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.

  server.prependOnceListener('connection', (stream) => {  console.log('Ah, we have our first user!');});
  

  Returns a reference to the EventEmitter, so that calls can be chained.

  Type Parameters

  • K

  Parameters

  • eventName: string | symbol

    The name of the event.

  • listener: (...args: any[]) => void

    The callback function

  Returns this

  Since

  v6.0.0

rawListeners

• rawListeners<K>(eventName: string | symbol): Function[]

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

  import { EventEmitter } from 'node:events';const emitter = new EventEmitter();emitter.once('log', () => console.log('log once'));// Returns a new Array with a function `onceWrapper` which has a property// `listener` which contains the original listener bound aboveconst listeners = emitter.rawListeners('log');const logFnWrapper = listeners[0];// Logs "log once" to the console and does not unbind the `once` eventlogFnWrapper.listener();// Logs "log once" to the console and removes the listenerlogFnWrapper();emitter.on('log', () => console.log('log persistently'));// Will return a new Array with a single function bound by `.on()` aboveconst newListeners = emitter.rawListeners('log');// Logs "log persistently" twicenewListeners[0]();emitter.emit('log');
  

  Type Parameters

  • K

  Parameters

  • eventName: string | symbol

  Returns Function[]

  Since

  v9.4.0

removeAllListeners

• removeAllListeners(eventName?: string | symbol): this

  Removes all listeners, or those of the specified eventName.

  It is bad practice to remove listeners added elsewhere in the code, particularly when the EventEmitter instance was created by some other component or module (e.g. sockets or file streams).

  Returns a reference to the EventEmitter, so that calls can be chained.

  Parameters

  • OptionaleventName: string | symbol

  Returns this

  Since

  v0.1.26

removeListener

• removeListener<K>(
      eventName: string | symbol,
      listener: (...args: any[]) => void,
  ): this

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

  const callback = (stream) => {  console.log('someone connected!');};server.on('connection', callback);// ...server.removeListener('connection', callback);
  

  removeListener() will remove, at most, one instance of a listener from the listener array. If any single listener has been added multiple times to the listener array for the specified eventName, then removeListener() must be called multiple times to remove each instance.

  Once an event is emitted, all listeners attached to it at the time of emitting are called in order. This implies that any removeListener() or removeAllListeners() calls after emitting and before the last listener finishes execution will not remove them fromemit() in progress. Subsequent events behave as expected.

  import { EventEmitter } from 'node:events';class MyEmitter extends EventEmitter {}const myEmitter = new MyEmitter();const callbackA = () => {  console.log('A');  myEmitter.removeListener('event', callbackB);};const callbackB = () => {  console.log('B');};myEmitter.on('event', callbackA);myEmitter.on('event', callbackB);// callbackA removes listener callbackB but it will still be called.// Internal listener array at time of emit [callbackA, callbackB]myEmitter.emit('event');// Prints://   A//   B// callbackB is now removed.// Internal listener array [callbackA]myEmitter.emit('event');// Prints://   A
  

  Because listeners are managed using an internal array, calling this will change the position indices of any listener registered after the listener being removed. This will not impact the order in which listeners are called, but it means that any copies of the listener array as returned by the emitter.listeners() method will need to be recreated.

  When a single function has been added as a handler multiple times for a single event (as in the example below), removeListener() will remove the most recently added instance. In the example the once('ping') listener is removed:

  import { EventEmitter } from 'node:events';const ee = new EventEmitter();function pong() {  console.log('pong');}ee.on('ping', pong);ee.once('ping', pong);ee.removeListener('ping', pong);ee.emit('ping');ee.emit('ping');
  

  Returns a reference to the EventEmitter, so that calls can be chained.

  Type Parameters

  • K

  Parameters

  • eventName: string | symbol
  • listener: (...args: any[]) => void

  Returns this

  Since

  v0.1.26

setMaxListeners

• setMaxListeners(n: number): this

  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.

  Returns a reference to the EventEmitter, so that calls can be chained.

  Parameters

  • n: number

  Returns this

  Since

  v0.3.5

StaticaddAbortListener

• addAbortListener(
      signal: AbortSignal,
      resource: (event: Event) => void,
  ): Disposable
  Experimental

  Listens once to the abort event on the provided signal.

  Listening to the abort event on abort signals is unsafe and may lead to resource leaks since another third party with the signal can call e.stopImmediatePropagation(). Unfortunately Node.js cannot change this since it would violate the web standard. Additionally, the original API makes it easy to forget to remove listeners.

  This API allows safely using AbortSignals in Node.js APIs by solving these two issues by listening to the event such that stopImmediatePropagation does not prevent the listener from running.

  Returns a disposable so that it may be unsubscribed from more easily.

  import { addAbortListener } from 'node:events';function example(signal) {  let disposable;  try {    signal.addEventListener('abort', (e) => e.stopImmediatePropagation());    disposable = addAbortListener(signal, (e) => {      // Do something when signal is aborted.    });  } finally {    disposable?.[Symbol.dispose]();  }}
  

  Parameters

  • signal: AbortSignal
  • resource: (event: Event) => void

  Returns Disposable

  Disposable that removes the abort listener.

  Since

  v20.5.0

StaticgetEventListeners

• getEventListeners(
      emitter: EventTarget | EventEmitter<DefaultEventMap>,
      name: string | symbol,
  ): Function[]

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

  For EventEmitters this behaves exactly the same as calling .listeners on the emitter.

  For EventTargets this is the only way to get the event listeners for the event target. This is useful for debugging and diagnostic purposes.

  import { getEventListeners, EventEmitter } from 'node:events';{  const ee = new EventEmitter();  const listener = () => console.log('Events are fun');  ee.on('foo', listener);  console.log(getEventListeners(ee, 'foo')); // [ [Function: listener] ]}{  const et = new EventTarget();  const listener = () => console.log('Events are fun');  et.addEventListener('foo', listener);  console.log(getEventListeners(et, 'foo')); // [ [Function: listener] ]}
  

  Parameters

  • emitter: EventTarget | EventEmitter<DefaultEventMap>
  • name: string | symbol

  Returns Function[]

  Since

  v15.2.0, v14.17.0

StaticgetMaxListeners

• getMaxListeners(emitter: EventTarget | EventEmitter<DefaultEventMap>): number

  Returns the currently set max amount of listeners.

  For EventEmitters this behaves exactly the same as calling .getMaxListeners on the emitter.

  For EventTargets this is the only way to get the max event listeners for the event target. If the number of event handlers on a single EventTarget exceeds the max set, the EventTarget will print a warning.

  import { getMaxListeners, setMaxListeners, EventEmitter } from 'node:events';{  const ee = new EventEmitter();  console.log(getMaxListeners(ee)); // 10  setMaxListeners(11, ee);  console.log(getMaxListeners(ee)); // 11}{  const et = new EventTarget();  console.log(getMaxListeners(et)); // 10  setMaxListeners(11, et);  console.log(getMaxListeners(et)); // 11}
  

  Parameters

  • emitter: EventTarget | EventEmitter<DefaultEventMap>

  Returns number

  Since

  v19.9.0

StaticlistenerCount

• listenerCount(emitter: EventEmitter, eventName: string | symbol): number

  A class method that returns the number of listeners for the given eventName registered on the given emitter.

  import { EventEmitter, listenerCount } from 'node:events';const myEmitter = new EventEmitter();myEmitter.on('event', () => {});myEmitter.on('event', () => {});console.log(listenerCount(myEmitter, 'event'));// Prints: 2
  

  Parameters

  • emitter: EventEmitter

    The emitter to query

  • eventName: string | symbol

    The event name

  Returns number

  Since

  v0.9.12

  Deprecated

  Since v3.2.0 - Use listenerCount instead.

Staticon

• on(
      emitter: EventEmitter,
      eventName: string | symbol,
      options?: StaticEventEmitterOptions,
  ): AsyncIterableIterator<any>

  import { on, EventEmitter } from 'node:events';import process from 'node:process';const ee = new EventEmitter();// Emit later onprocess.nextTick(() => {  ee.emit('foo', 'bar');  ee.emit('foo', 42);});for await (const event of on(ee, 'foo')) {  // The execution of this inner block is synchronous and it  // processes one event at a time (even with await). Do not use  // if concurrent execution is required.  console.log(event); // prints ['bar'] [42]}// Unreachable here
  

  Returns an AsyncIterator that iterates eventName events. It will throw if the EventEmitter emits 'error'. It removes all listeners when exiting the loop. The value returned by each iteration is an array composed of the emitted event arguments.

  An AbortSignal can be used to cancel waiting on events:

  import { on, EventEmitter } from 'node:events';import process from 'node:process';const ac = new AbortController();(async () => {  const ee = new EventEmitter();  // Emit later on  process.nextTick(() => {    ee.emit('foo', 'bar');    ee.emit('foo', 42);  });  for await (const event of on(ee, 'foo', { signal: ac.signal })) {    // The execution of this inner block is synchronous and it    // processes one event at a time (even with await). Do not use    // if concurrent execution is required.    console.log(event); // prints ['bar'] [42]  }  // Unreachable here})();process.nextTick(() => ac.abort());
  

  Parameters

  • emitter: EventEmitter
  • eventName: string | symbol

    The name of the event being listened for

  • Optionaloptions: StaticEventEmitterOptions

  Returns AsyncIterableIterator<any>

  An AsyncIterator that iterates eventName events emitted by the emitter

  Since

  v13.6.0, v12.16.0

• on(
      emitter: EventTarget,
      eventName: string,
      options?: StaticEventEmitterOptions,
  ): AsyncIterableIterator<any>

  import { on, EventEmitter } from 'node:events';import process from 'node:process';const ee = new EventEmitter();// Emit later onprocess.nextTick(() => {  ee.emit('foo', 'bar');  ee.emit('foo', 42);});for await (const event of on(ee, 'foo')) {  // The execution of this inner block is synchronous and it  // processes one event at a time (even with await). Do not use  // if concurrent execution is required.  console.log(event); // prints ['bar'] [42]}// Unreachable here
  

  Returns an AsyncIterator that iterates eventName events. It will throw if the EventEmitter emits 'error'. It removes all listeners when exiting the loop. The value returned by each iteration is an array composed of the emitted event arguments.

  An AbortSignal can be used to cancel waiting on events:

  import { on, EventEmitter } from 'node:events';import process from 'node:process';const ac = new AbortController();(async () => {  const ee = new EventEmitter();  // Emit later on  process.nextTick(() => {    ee.emit('foo', 'bar');    ee.emit('foo', 42);  });  for await (const event of on(ee, 'foo', { signal: ac.signal })) {    // The execution of this inner block is synchronous and it    // processes one event at a time (even with await). Do not use    // if concurrent execution is required.    console.log(event); // prints ['bar'] [42]  }  // Unreachable here})();process.nextTick(() => ac.abort());
  

  Parameters

  • emitter: EventTarget
  • eventName: string

    The name of the event being listened for

  • Optionaloptions: StaticEventEmitterOptions

  Returns AsyncIterableIterator<any>

  An AsyncIterator that iterates eventName events emitted by the emitter

  Since

  v13.6.0, v12.16.0

Staticonce

• once(
      emitter: EventEmitter,
      eventName: string | symbol,
      options?: Pick<StaticEventEmitterOptions, "signal">,
  ): Promise<any[]>

  Creates a Promise that is fulfilled when the EventEmitter emits the given event or that is rejected if the EventEmitter emits 'error' while waiting. The Promise will resolve with an array of all the arguments emitted to the given event.

  This method is intentionally generic and works with the web platform EventTarget interface, which has no special'error' event semantics and does not listen to the 'error' event.

  import { once, EventEmitter } from 'node:events';import process from 'node:process';const ee = new EventEmitter();process.nextTick(() => {  ee.emit('myevent', 42);});const [value] = await once(ee, 'myevent');console.log(value);const err = new Error('kaboom');process.nextTick(() => {  ee.emit('error', err);});try {  await once(ee, 'myevent');} catch (err) {  console.error('error happened', err);}
  

  The special handling of the 'error' event is only used when events.once() is used to wait for another event. If events.once() is used to wait for the 'error' event itself, then it is treated as any other kind of event without special handling:

  import { EventEmitter, once } from 'node:events';const ee = new EventEmitter();once(ee, 'error')  .then(([err]) => console.log('ok', err.message))  .catch((err) => console.error('error', err.message));ee.emit('error', new Error('boom'));// Prints: ok boom
  

  An AbortSignal can be used to cancel waiting for the event:

  import { EventEmitter, once } from 'node:events';const ee = new EventEmitter();const ac = new AbortController();async function foo(emitter, event, signal) {  try {    await once(emitter, event, { signal });    console.log('event emitted!');  } catch (error) {    if (error.name === 'AbortError') {      console.error('Waiting for the event was canceled!');    } else {      console.error('There was an error', error.message);    }  }}foo(ee, 'foo', ac.signal);ac.abort(); // Abort waiting for the eventee.emit('foo'); // Prints: Waiting for the event was canceled!
  

  Parameters

  • emitter: EventEmitter
  • eventName: string | symbol
  • Optionaloptions: Pick<StaticEventEmitterOptions, "signal">

  Returns Promise<any[]>

  Since

  v11.13.0, v10.16.0

• once(
      emitter: EventTarget,
      eventName: string,
      options?: StaticEventEmitterOptions,
  ): Promise<any[]>

  Creates a Promise that is fulfilled when the EventEmitter emits the given event or that is rejected if the EventEmitter emits 'error' while waiting. The Promise will resolve with an array of all the arguments emitted to the given event.

  This method is intentionally generic and works with the web platform EventTarget interface, which has no special'error' event semantics and does not listen to the 'error' event.

  import { once, EventEmitter } from 'node:events';import process from 'node:process';const ee = new EventEmitter();process.nextTick(() => {  ee.emit('myevent', 42);});const [value] = await once(ee, 'myevent');console.log(value);const err = new Error('kaboom');process.nextTick(() => {  ee.emit('error', err);});try {  await once(ee, 'myevent');} catch (err) {  console.error('error happened', err);}
  

  The special handling of the 'error' event is only used when events.once() is used to wait for another event. If events.once() is used to wait for the 'error' event itself, then it is treated as any other kind of event without special handling:

  import { EventEmitter, once } from 'node:events';const ee = new EventEmitter();once(ee, 'error')  .then(([err]) => console.log('ok', err.message))  .catch((err) => console.error('error', err.message));ee.emit('error', new Error('boom'));// Prints: ok boom
  

  An AbortSignal can be used to cancel waiting for the event:

  import { EventEmitter, once } from 'node:events';const ee = new EventEmitter();const ac = new AbortController();async function foo(emitter, event, signal) {  try {    await once(emitter, event, { signal });    console.log('event emitted!');  } catch (error) {    if (error.name === 'AbortError') {      console.error('Waiting for the event was canceled!');    } else {      console.error('There was an error', error.message);    }  }}foo(ee, 'foo', ac.signal);ac.abort(); // Abort waiting for the eventee.emit('foo'); // Prints: Waiting for the event was canceled!
  

  Parameters

  • emitter: EventTarget
  • eventName: string
  • Optionaloptions: StaticEventEmitterOptions

  Returns Promise<any[]>

  Since

  v11.13.0, v10.16.0

StaticsetMaxListeners

• setMaxListeners(
      n?: number,
      ...eventTargets: (EventTarget | EventEmitter<DefaultEventMap>)[],
  ): void

  import { setMaxListeners, EventEmitter } from 'node:events';const target = new EventTarget();const emitter = new EventEmitter();setMaxListeners(5, target, emitter);
  

  Parameters

  • Optionaln: number

    A non-negative number. The maximum number of listeners per EventTarget event.

  • ...eventTargets: (EventTarget | EventEmitter<DefaultEventMap>)[]

  Returns void

  Since

  v15.4.0