xdash

Appearance

xdash API Reference v0.5.14

xdash API Reference / Invalidator

Class: Invalidator ​

Defined in: src/cache.ts:8

A class that emits an event when invalidated

Extends ​

  • EventEmitter

Constructors ​

Constructor ​

new Invalidator(options?): Invalidator

Defined in: node_modules/@types/node/events.d.ts:127

Parameters ​

options? ​

EventEmitterOptions

Returns ​

Invalidator

Inherited from ​

EventEmitter.constructor

Properties ​

captureRejections ​

static captureRejections: boolean

Defined in: node_modules/@types/node/events.d.ts:426

Value: boolean

Change the default captureRejections option on all new EventEmitter objects.

Since ​

v13.4.0, v12.16.0

Inherited from ​

EventEmitter.captureRejections

captureRejectionSymbol ​

readonly static captureRejectionSymbol: typeof captureRejectionSymbol

Defined in: node_modules/@types/node/events.d.ts:419

Value: Symbol.for('nodejs.rejection')

See how to write a custom rejection handler.

Since ​

v13.4.0, v12.16.0

Inherited from ​

EventEmitter.captureRejectionSymbol

defaultMaxListeners ​

static defaultMaxListeners: number

Defined in: node_modules/@types/node/events.d.ts:463

By default, a maximum of 10 listeners can be registered for any single event. This limit can be changed for individual EventEmitter instances using the emitter.setMaxListeners(n) method. To change the default for allEventEmitter instances, the events.defaultMaxListenersproperty can be used. If this value is not a positive number, a RangeErroris thrown.

Take caution when setting the events.defaultMaxListeners because the change affects allEventEmitter instances, including those created before the change is made. However, calling emitter.setMaxListeners(n) still has precedence over events.defaultMaxListeners.

This is not a hard limit. The EventEmitter instance will allow more listeners to be added but will output a trace warning to stderr indicating that a "possible EventEmitter memory leak" has been detected. For any singleEventEmitter, the emitter.getMaxListeners() and emitter.setMaxListeners()methods can be used to temporarily avoid this warning:

js
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));
});

The --trace-warnings command-line flag can be used to display the stack trace for such warnings.

The emitted warning can be inspected with process.on('warning') and will have the additional emitter, type, and count properties, referring to the event emitter instance, the event's name and the number of attached listeners, respectively. Its name property is set to 'MaxListenersExceededWarning'.

Since ​

v0.11.2

Inherited from ​

EventEmitter.defaultMaxListeners

errorMonitor ​

readonly static errorMonitor: typeof errorMonitor

Defined in: node_modules/@types/node/events.d.ts:412

This symbol shall be used to install a listener for only monitoring 'error'events. Listeners installed using this symbol are called before the regular'error' listeners are called.

Installing a listener using this symbol does not change the behavior once an'error' event is emitted. Therefore, the process will still crash if no regular 'error' listener is installed.

Since ​

v13.6.0, v12.17.0

Inherited from ​

EventEmitter.errorMonitor

Methods ​

[captureRejectionSymbol]()? ​

optional [captureRejectionSymbol]<K>(error, event, ...args): void

Defined in: node_modules/@types/node/events.d.ts:129

Type Parameters ​

K ​

K

Parameters ​

error ​

Error

event ​

string | symbol

args ​

...AnyRest

Returns ​

void

Inherited from ​

EventEmitter.[captureRejectionSymbol]

addListener() ​

addListener<K>(eventName, listener): this

Defined in: node_modules/@types/node/events.d.ts:562

Alias for emitter.on(eventName, listener).

Type Parameters ​

K ​

K

Parameters ​

eventName ​

string | symbol

listener ​

(...args) => void

Returns ​

this

Since ​

v0.1.26

Inherited from ​

EventEmitter.addListener

emit() ​

emit<K>(eventName, ...args): boolean

Defined in: node_modules/@types/node/events.d.ts:824

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

Returns true if the event had listeners, false otherwise.

js
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 ​

K

Parameters ​

eventName ​

string | symbol

args ​

...AnyRest

Returns ​

boolean

Since ​

v0.1.26

Inherited from ​

EventEmitter.emit

eventNames() ​

eventNames(): (string | symbol)[]

Defined in: node_modules/@types/node/events.d.ts:887

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

js
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

Inherited from ​

EventEmitter.eventNames

getMaxListeners() ​

getMaxListeners(): number

Defined in: node_modules/@types/node/events.d.ts:739

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

Inherited from ​

EventEmitter.getMaxListeners

invalidate() ​

invalidate(): void

Defined in: src/cache.ts:9

Returns ​

void

listenerCount() ​

listenerCount<K>(eventName, listener?): number

Defined in: node_modules/@types/node/events.d.ts:833

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 ​

K

Parameters ​

eventName ​

The name of the event being listened for

string | symbol

listener? ​

Function

The event handler function

Returns ​

number

Since ​

v3.2.0

Inherited from ​

EventEmitter.listenerCount

listeners() ​

listeners<K>(eventName): Function[]

Defined in: node_modules/@types/node/events.d.ts:752

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

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

Type Parameters ​

K ​

K

Parameters ​

eventName ​

string | symbol

Returns ​

Function[]

Since ​

v0.1.26

Inherited from ​

EventEmitter.listeners

off() ​

off<K>(eventName, listener): this

Defined in: node_modules/@types/node/events.d.ts:712

Alias for emitter.removeListener().

Type Parameters ​

K ​

K

Parameters ​

eventName ​

string | symbol

listener ​

(...args) => void

Returns ​

this

Since ​

v10.0.0

Inherited from ​

EventEmitter.off

on() ​

on<K>(eventName, listener): this

Defined in: node_modules/@types/node/events.d.ts:594

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 eventNameand listener will result in the listener being added, and called, multiple times.

js
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. Theemitter.prependListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.

js
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 ​

K

Parameters ​

eventName ​

The name of the event.

string | symbol

listener ​

(...args) => void

The callback function

Returns ​

this

Since ​

v0.1.101

Inherited from ​

EventEmitter.on

once() ​

once<K>(eventName, listener): this

Defined in: node_modules/@types/node/events.d.ts:624

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

js
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. Theemitter.prependOnceListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.

js
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 ​

K

Parameters ​

eventName ​

The name of the event.

string | symbol

listener ​

(...args) => void

The callback function

Returns ​

this

Since ​

v0.3.0

Inherited from ​

EventEmitter.once

prependListener() ​

prependListener<K>(eventName, listener): this

Defined in: node_modules/@types/node/events.d.ts:851

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 eventNameand listener will result in the listener being added, and called, multiple times.

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

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

Type Parameters ​

K ​

K

Parameters ​

eventName ​

The name of the event.

string | symbol

listener ​

(...args) => void

The callback function

Returns ​

this

Since ​

v6.0.0

Inherited from ​

EventEmitter.prependListener

prependOnceListener() ​

prependOnceListener<K>(eventName, listener): this

Defined in: node_modules/@types/node/events.d.ts:867

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.

js
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 ​

K

Parameters ​

eventName ​

The name of the event.

string | symbol

listener ​

(...args) => void

The callback function

Returns ​

this

Since ​

v6.0.0

Inherited from ​

EventEmitter.prependOnceListener

rawListeners() ​

rawListeners<K>(eventName): Function[]

Defined in: node_modules/@types/node/events.d.ts:783

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

js
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 ​

K

Parameters ​

eventName ​

string | symbol

Returns ​

Function[]

Since ​

v9.4.0

Inherited from ​

EventEmitter.rawListeners

removeAllListeners() ​

removeAllListeners(event?): this

Defined in: node_modules/@types/node/events.d.ts:723

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 ​

event? ​

string | symbol

Returns ​

this

Since ​

v0.1.26

Inherited from ​

EventEmitter.removeAllListeners

removeListener() ​

removeListener<K>(eventName, listener): this

Defined in: node_modules/@types/node/events.d.ts:707

Removes the specified listener from the listener array for the event namedeventName.

js
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 anyremoveListener() or removeAllListeners() calls after emitting and before the last listener finishes execution will not remove them fromemit() in progress. Subsequent events behave as expected.

js
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:

js
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 ​

K

Parameters ​

eventName ​

string | symbol

listener ​

(...args) => void

Returns ​

this

Since ​

v0.1.26

Inherited from ​

EventEmitter.removeListener

setMaxListeners() ​

setMaxListeners(n): this

Defined in: node_modules/@types/node/events.d.ts:733

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 toInfinity (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

Inherited from ​

EventEmitter.setMaxListeners

addAbortListener() ​

static addAbortListener(signal, resource): Disposable

Defined in: node_modules/@types/node/events.d.ts:404

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.

js
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) => void

Returns ​

Disposable

Disposable that removes the abort listener.

Since ​

v20.5.0

Inherited from ​

EventEmitter.addAbortListener

getEventListeners() ​

static getEventListeners(emitter, name): Function[]

Defined in: node_modules/@types/node/events.d.ts:325

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.

js
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> | _DOMEventTarget

name ​

string | symbol

Returns ​

Function[]

Since ​

v15.2.0, v14.17.0

Inherited from ​

EventEmitter.getEventListeners

getMaxListeners() ​

static getMaxListeners(emitter): number

Defined in: node_modules/@types/node/events.d.ts:354

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.

js
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> | _DOMEventTarget

Returns ​

number

Since ​

v19.9.0

Inherited from ​

EventEmitter.getMaxListeners

listenerCount() ​

static listenerCount(emitter, eventName): number

Defined in: node_modules/@types/node/events.d.ts:297

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

js
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 ​

The event name

string | symbol

Returns ​

number

Since ​

v0.9.12

Deprecated ​

Since v3.2.0 - Use listenerCount instead.

Inherited from ​

EventEmitter.listenerCount

on() ​

static on(emitter, eventName, options?): AsyncIterableIterator<any>

Defined in: node_modules/@types/node/events.d.ts:275

js
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:

js
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

The name of the event being listened for

options? ​

StaticEventEmitterOptions

Returns ​

AsyncIterableIterator<any>

that iterates eventName events emitted by the emitter

Since ​

v13.6.0, v12.16.0

Inherited from ​

EventEmitter.on

once() ​

Call Signature ​

static once(emitter, eventName, options?): Promise<any[]>

Defined in: node_modules/@types/node/events.d.ts:210

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.

js
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:

js
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:

js
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 ​

_NodeEventTarget

eventName ​

string | symbol

options? ​

StaticEventEmitterOptions

Returns ​

Promise<any[]>

Since ​

v11.13.0, v10.16.0

Inherited from ​

EventEmitter.once

Call Signature ​

static once(emitter, eventName, options?): Promise<any[]>

Defined in: node_modules/@types/node/events.d.ts:215

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.

js
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:

js
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:

js
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 ​

_DOMEventTarget

eventName ​

string

options? ​

StaticEventEmitterOptions

Returns ​

Promise<any[]>

Since ​

v11.13.0, v10.16.0

Inherited from ​

EventEmitter.once

setMaxListeners() ​

static setMaxListeners(n?, ...eventTargets?): void

Defined in: node_modules/@types/node/events.d.ts:369

js
import { setMaxListeners, EventEmitter } from 'node:events';

const target = new EventTarget();
const emitter = new EventEmitter();

setMaxListeners(5, target, emitter);

Parameters ​

n? ​

number

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

eventTargets? ​

...(EventEmitter<DefaultEventMap> | _DOMEventTarget)[]

Returns ​

void

Since ​

v15.4.0

Inherited from ​

EventEmitter.setMaxListeners

Released under the MIT License.

Copyright © 2024-present Kyle Tse