Class ArrowLayerWeather Plus

id

renderingMode

type

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

addSource

• addSource(
      time: number,
      url: string,
      loadedCallback?:
          | ((tile: Tile, url?: string, error?: ErrorEvent | null) => void)
          | null,
  ): void

  Adds another frame to the animation.

  Parameters

  • time: number

    Time of the data in this frame. Should be unique.

  • url: string

    URL to the tiles. Expected to have {zxy} placeholder to be dynamically replaced with z/x/y coordinates.

  • OptionalloadedCallback: ((tile: Tile, url?: string, error?: ErrorEvent | null) => void) | null

  Returns void

animate

• animate(timePerSecond: number): void

  Changes the speed of the animation. 0 to stop. The speed is in number of real world milliseconds per animation second. Example: if timePerSecond is set to 10*1000, then the animation will run 10x of real world speed.

  Parameters

  • timePerSecond: number

  Returns void

animateByFactor

• animateByFactor(factor: number): void

  Animate by a factor of real life speed. Exampe, if factor is 10, then the animation will play at 10 times the real life speed.

  Parameters

  • factor: number

  Returns void

computeCurrentMixedImage

• computeCurrentMixedImage(
      __namedParameters: {
          blurKernel?: number;
          channel?: string;
          outputSize?: number;
          zxy?: string;
      },
  ): ImageData
  | null

  Get the current mixed image as a ImageData, meaning with pixel data, width, height and number of channels Used by: Weather Plus

  Parameters

  • __namedParameters: { blurKernel?: number; channel?: string; outputSize?: number; zxy?: string }

  Returns ImageData | null

  ImageData | null

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 listener
  myEmitter.on('event', function firstListener() {
    console.log('Helloooo! first listener');
  });
  // Second listener
  myEmitter.on('event', function secondListener(arg1, arg2) {
    console.log(`event with parameters ${arg1}, ${arg2} in second listener`);
  });
  // Third listener
  myEmitter.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

forceRepaint

• forceRepaint(): void

  The method simplifies the access to the triggerRepaint method

  Returns void

getAnimationEnd

• getAnimationEnd(): number

  Get the end time of the animation or -Infinity if empty.

  Returns number

getAnimationEndDate

• getAnimationEndDate(): Date

  Get the animation end as a date object

  Returns Date

getAnimationSpeed

• getAnimationSpeed(): number

  Get the speed of the animation. The speed is in number of real world seconds per animation second.

  Returns number

getAnimationStart

• getAnimationStart(): number

  Get the time of the first TimeFrame (always the begining of the animation). If the frame container is empty, returns Infinity

  Returns number

getAnimationStartDate

• getAnimationStartDate(): Date

  Get the animation start as a Date object

  Returns Date

getAnimationTime

• getAnimationTime(): number

  Get the current time of the animation

  Returns number

getAnimationTimeDate

• getAnimationTimeDate(): Date

  Get the current time of the animation as a Date object

  Returns Date

getMaxListeners

• getMaxListeners(): number

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

  Returns number

  Since

  v1.0.0

getRepaintOnPausedAnimation

• getRepaintOnPausedAnimation(): boolean

  Get whether or not the frames continues to rendered on a paused animation

  Returns boolean

getVisibleExtent

• getVisibleExtent(scale?: number): Extent | null

  Get the Extent as defined in OL

  Parameters

  • Optionalscale: number

  Returns Extent | null

getWantedTiles

• getWantedTiles(currentZ: number, minZoom: number, maxZoom: number): TileList

  Get the list of all the tiles wanted for this extent and from the min zoom to the max zoom. This is used to prevent updating tiles that are not in this list in .updateSlippyTile()

  Parameters

  • currentZ: number
  • minZoom: number
  • maxZoom: number

  Returns TileList

isPlaying

• isPlaying(): boolean

  Tells whether the animation is currently playing

  Returns boolean

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

off

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

  Alias for emitter.removeListener().

  Type Parameters

  • K

  Parameters

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

  Returns this

  Since

  v10.0.0

on

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

  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.

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

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

  By default, event listeners are invoked in the order they are added. The emitter.prependListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.

  import { EventEmitter } from 'node:events';
  const myEE = new EventEmitter();
  myEE.on('foo', () => console.log('a'));
  myEE.prependListener('foo', () => console.log('b'));
  myEE.emit('foo');
  // Prints:
  //   b
  //   a
  

  Type Parameters

  • K

  Parameters

  • eventName: string | symbol

    The name of the event.

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

    The callback function

  Returns this

  Since

  v0.1.101

once

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

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

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

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

  By default, event listeners are invoked in the order they are added. The emitter.prependOnceListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.

  import { EventEmitter } from 'node:events';
  const myEE = new EventEmitter();
  myEE.once('foo', () => console.log('a'));
  myEE.prependOnceListener('foo', () => console.log('b'));
  myEE.emit('foo');
  // Prints:
  //   b
  //   a
  

  Type Parameters

  • K

  Parameters

  • eventName: string | symbol

    The name of the event.

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

    The callback function

  Returns this

  Since

  v0.3.0

onProjectionChanged

• onProjectionChanged(event: MapProjectionEvent): void

  Parameters

  • event: MapProjectionEvent

  Returns void

  Description

  Event handler - called when projection is changed

onRemove

• onRemove(_map: Map, _gl: WebGLRenderingContext | WebGL2RenderingContext): void

  The method is called when the layer is removed from the map CustomLayerInterface method

  Parameters

  • _map: Map
  • _gl: WebGLRenderingContext | WebGL2RenderingContext

  Returns void

pick

• pick(
      lng: number,
      lat: number,
      options?: { bilinear?: boolean; highestRes?: boolean; load?: boolean },
  ): number[] | null

  Picks the best currently available values at the position.

  The values are read from the already loaded tiles at the current time.

  Return the interpolated array of decoded values of the same length as the number of specified coloring fragments.

  If the coloring fragments uses more channels (e.g. "rg"), the corresponding value is an array of [r value, g value, sqrt(r^2 + g^2)].

  Parameters

  • lng: number
  • lat: number
  • Optionaloptions: { bilinear?: boolean; highestRes?: boolean; load?: boolean }

    • Optionalbilinear?: boolean

      Enable bilinear interpolation if true, otherwise, the picking will be based on the nearest neighbor (NN) pixel. NN has less impact on performance because it requires less texture reading, so it is generaly faster. Bilinear is more precise and will retrieve values that are closer to what is being displayed (since tiles are rendered using a native-GPU bilinear method) Default: false

    • OptionalhighestRes?: boolean

      If true, the picking will be perfomed on the highest resolution tile available. If false, the picking is done on the tile currently showing on the map.

    • Optionalload?: boolean

      Will force the loading of the tile if it was not already cached. Usually unnecesary when the picking is done from hovering the pointer on the map, unless the option .highRes is true. Default: false.

  Returns number[] | null

  Array of decoded interpolated values. In case of using a multi-channel coloring fragment, the returned value is an array where the first value is the value and the second is the category

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

prerender

• prerender(
      _gl: WebGLRenderingContext | WebGL2RenderingContext,
      options: CustomRenderMethodInput,
  ): void

  CustomLayerInterface method This is used to apply the map matrix to the local camera

  Parameters

  • _gl: WebGLRenderingContext | WebGL2RenderingContext
  • options: CustomRenderMethodInput

  Returns void

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 above
  const listeners = emitter.rawListeners('log');
  const logFnWrapper = listeners[0];
  
  // Logs "log once" to the console and does not unbind the `once` event
  logFnWrapper.listener();
  
  // Logs "log once" to the console and removes the listener
  logFnWrapper();
  
  emitter.on('log', () => console.log('log persistently'));
  // Will return a new Array with a single function bound by `.on()` above
  const newListeners = emitter.rawListeners('log');
  
  // Logs "log persistently" twice
  newListeners[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

removeSource

• removeSource(time: number): void

  Removes frame

  Parameters

  • time: number

  Returns void

render

• render(
      _gl: WebGLRenderingContext | WebGL2RenderingContext,
      _options: CustomRenderMethodInput,
  ): void

  CustomLayerInterface method It is used to render the local tiles into the MapTiler SDK context

  Parameters

  • _gl: WebGLRenderingContext | WebGL2RenderingContext
  • _options: CustomRenderMethodInput

  Returns void

setAnimationTime

• setAnimationTime(time: number): void

  Change the visualization to a specific time. Does not stop animation.

  Parameters

  • time: number

  Returns void

setCategorySmoothTransition

• setCategorySmoothTransition(cst: boolean): void

  Enable smoothing category color when true. Hard edge between categories when false. This seeting applies only to TileLayers using MultiChannelGradientColoringFragment as the other types of oloring fragment do not use categories.

  Parameters

  • cst: boolean

  Returns void

setLocalSmoothing

• setLocalSmoothing(s: boolean): void

  If true, enables the local smoothing

  Parameters

  • s: boolean

  Returns void

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

setMaxSmoothingDistance

• setMaxSmoothingDistance(d: number): void

  Defines the size of the smoothing kernel

  Parameters

  • d: number

  Returns void

setRepaintOnPausedAnimation

• setRepaintOnPausedAnimation(r: boolean): void

  If true, even the paused animation is rendered up to 60 times per seconds. If false, the rendering is paused when the animation is paused. Pausing the animation has side effects:

  • it lowers energy consumtion
  • it prevents overheating
  • it pauses time-independant annimation (arrows, particles)

  Parameters

  • r: boolean

  Returns void

setSmoothingDistanceDecayFactor

• setSmoothingDistanceDecayFactor(f: number): void

  Defines by what factor the smoothing kernel size is reduced with increasing zoom level

  Parameters

  • f: number

  Returns void

setTimeInterpolation

• setTimeInterpolation(ti: boolean): void

  Enables data interpolation between keyframes when true. Only shows keyframe data when false.

  Parameters

  • ti: boolean

  Returns void

StaticaddAbortListener

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

  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

  Experimental

StaticgetEventListeners

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

  Returns Function[]

  Since

  v15.2.0, v14.17.0

StaticgetMaxListeners

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

  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?: StaticEventEmitterIteratorOptions,
  ): AsyncIterator<any[]>

  import { on, EventEmitter } from 'node:events';
  import process from 'node:process';
  
  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')) {
    // 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());
  

  Use the close option to specify an array of event names that will end the iteration:

  import { on, EventEmitter } from 'node:events';
  import process from 'node:process';
  
  const ee = new EventEmitter();
  
  // Emit later on
  process.nextTick(() => {
    ee.emit('foo', 'bar');
    ee.emit('foo', 42);
    ee.emit('close');
  });
  
  for await (const event of on(ee, 'foo', { close: ['close'] })) {
    console.log(event); // prints ['bar'] [42]
  }
  // the loop will exit after 'close' is emitted
  console.log('done'); // prints 'done'
  

  Parameters

  • emitter: EventEmitter
  • eventName: string | symbol
  • Optionaloptions: StaticEventEmitterIteratorOptions

  Returns AsyncIterator<any[]>

  An AsyncIterator that iterates eventName events emitted by the emitter

  Since

  v13.6.0, v12.16.0

• on(
      emitter: EventTarget,
      eventName: string,
      options?: StaticEventEmitterIteratorOptions,
  ): AsyncIterator<any[]>

  import { on, EventEmitter } from 'node:events';
  import process from 'node:process';
  
  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')) {
    // 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());
  

  Use the close option to specify an array of event names that will end the iteration:

  import { on, EventEmitter } from 'node:events';
  import process from 'node:process';
  
  const ee = new EventEmitter();
  
  // Emit later on
  process.nextTick(() => {
    ee.emit('foo', 'bar');
    ee.emit('foo', 42);
    ee.emit('close');
  });
  
  for await (const event of on(ee, 'foo', { close: ['close'] })) {
    console.log(event); // prints ['bar'] [42]
  }
  // the loop will exit after 'close' is emitted
  console.log('done'); // prints 'done'
  

  Parameters

  • emitter: EventTarget
  • eventName: string
  • Optionaloptions: StaticEventEmitterIteratorOptions

  Returns AsyncIterator<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?: 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 event
  ee.emit('foo'); // Prints: Waiting for the event was canceled!
  

  Parameters

  • emitter: EventEmitter
  • eventName: string | symbol
  • Optionaloptions: StaticEventEmitterOptions

  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 event
  ee.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: (EventEmitter<DefaultEventMap> | EventTarget)[],
  ): 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: (EventEmitter<DefaultEventMap> | EventTarget)[]

    Zero or more {EventTarget} or {EventEmitter} instances. If none are specified, n is set as the default max for all newly created {EventTarget} and {EventEmitter} objects.

  Returns void

  Since

  v15.4.0