Class: WSServer<T, U>

Type parameters

Name	Type
`T`	extends typeof `WebSocket.WebSocket` = typeof `WebSocket.WebSocket`
`U`	extends typeof `IncomingMessage` = typeof `IncomingMessage`

Hierarchy

EventEmitter

↳ WSServer

Constructors

constructor

• new WSServer<T, U>(options?, callback?)

Type parameters

Name	Type
`T`	extends typeof `WebSocket` = typeof `WebSocket`
`U`	extends typeof `IncomingMessage` = typeof `IncomingMessage`

Parameters

Name	Type
`options?`	`ServerOptions`<`T`, `U`>
`callback?`	() => `void`

Overrides

EventEmitter.constructor

Defined in

node_modules/@types/ws/index.d.ts:351

Properties

clients

• clients: Set<InstanceType<T>>

Defined in

node_modules/@types/ws/index.d.ts:349

options

• options: ServerOptions<T, U>

Defined in

node_modules/@types/ws/index.d.ts:347

path

• path: string

Defined in

node_modules/@types/ws/index.d.ts:348

captureRejectionSymbol

▪ Static Readonly captureRejectionSymbol: typeof captureRejectionSymbol

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

See how to write a custom rejection handler.

Since

v13.4.0, v12.16.0

Inherited from

EventEmitter.captureRejectionSymbol

Defined in

node_modules/@types/node/events.d.ts:402

captureRejections

▪ Static captureRejections: boolean

Value: boolean

Change the default captureRejections option on all new EventEmitter objects.

Since

v13.4.0, v12.16.0

Inherited from

EventEmitter.captureRejections

Defined in

node_modules/@types/node/events.d.ts:409

defaultMaxListeners

▪ Static defaultMaxListeners: number

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:

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

Defined in

node_modules/@types/node/events.d.ts:446

errorMonitor

▪ Static Readonly errorMonitor: typeof errorMonitor

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

Defined in

node_modules/@types/node/events.d.ts:395

Methods

[captureRejectionSymbol]

▸ Optional [captureRejectionSymbol](error, event, ...args): void

Parameters

Name	Type
`error`	`Error`
`event`	`string`
`...args`	`any`[]

Returns

void

Inherited from

EventEmitter.__@captureRejectionSymbol@26662

Defined in

node_modules/@types/node/events.d.ts:112

addListener

▸ addListener(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"connection"`
`cb`	(`client`: `InstanceType`<`T`>, `request`: `InstanceType`<`U`>) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.addListener

Defined in

node_modules/@types/ws/index.d.ts:388

▸ addListener(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"error"`
`cb`	(`err`: `Error`) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.addListener

Defined in

node_modules/@types/ws/index.d.ts:389

▸ addListener(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"headers"`
`cb`	(`headers`: `string`[], `request`: `InstanceType`<`U`>) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.addListener

Defined in

node_modules/@types/ws/index.d.ts:390

▸ addListener(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"close"` \| `"listening"`
`cb`	() => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.addListener

Defined in

node_modules/@types/ws/index.d.ts:391

▸ addListener(event, listener): WSServer<T, U>

Parameters

Name	Type
`event`	`string` \| `symbol`
`listener`	(...`args`: `any`[]) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.addListener

Defined in

node_modules/@types/ws/index.d.ts:392

address

▸ address(): string | AddressInfo

Returns

string | AddressInfo

Defined in

node_modules/@types/ws/index.d.ts:353

close

▸ close(cb?): void

Parameters

Name	Type
`cb?`	(`err?`: `Error`) => `void`

Returns

void

Defined in

node_modules/@types/ws/index.d.ts:354

emit

▸ emit(eventName, ...args): boolean

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.

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

Since

v0.1.26

Parameters

Name	Type
`eventName`	`string` \| `symbol`
`...args`	`any`[]

Returns

boolean

Inherited from

EventEmitter.emit

Defined in

node_modules/@types/node/events.d.ts:807

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) ]

Since

v6.0.0

Returns

(string | symbol)[]

Inherited from

EventEmitter.eventNames

Defined in

node_modules/@types/node/events.d.ts:870

getMaxListeners

▸ getMaxListeners(): number

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

Since

v1.0.0

Returns

number

Inherited from

EventEmitter.getMaxListeners

Defined in

node_modules/@types/node/events.d.ts:722

handleUpgrade

▸ handleUpgrade(request, socket, upgradeHead, callback): void

Parameters

Name	Type
`request`	`InstanceType`<`U`>
`socket`	`Duplex`
`upgradeHead`	`Buffer`
`callback`	(`client`: `InstanceType`<`T`>, `request`: `InstanceType`<`U`>) => `void`

Returns

void

Defined in

node_modules/@types/ws/index.d.ts:355

listenerCount

▸ listenerCount(eventName, listener?): 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.

Since

v3.2.0

Parameters

Name	Type	Description
`eventName`	`string` \| `symbol`	The name of the event being listened for
`listener?`	`Function`	The event handler function

Returns

number

Inherited from

EventEmitter.listenerCount

Defined in

node_modules/@types/node/events.d.ts:816

listeners

▸ listeners(eventName): 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] ]

Since

v0.1.26

Parameters

Name	Type
`eventName`	`string` \| `symbol`

Returns

Function[]

Inherited from

EventEmitter.listeners

Defined in

node_modules/@types/node/events.d.ts:735

off

▸ off(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"connection"`
`cb`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>, `socket`: `InstanceType`<`T`>, `request`: `InstanceType`<`U`>) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.off

Defined in

node_modules/@types/ws/index.d.ts:379

▸ off(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"error"`
`cb`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>, `error`: `Error`) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.off

Defined in

node_modules/@types/ws/index.d.ts:383

▸ off(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"headers"`
`cb`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>, `headers`: `string`[], `request`: `InstanceType`<`U`>) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.off

Defined in

node_modules/@types/ws/index.d.ts:384

▸ off(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"close"` \| `"listening"`
`cb`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.off

Defined in

node_modules/@types/ws/index.d.ts:385

▸ off(event, listener): WSServer<T, U>

Parameters

Name	Type
`event`	`string` \| `symbol`
`listener`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>, ...`args`: `any`[]) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.off

Defined in

node_modules/@types/ws/index.d.ts:386

on

▸ on(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"connection"`
`cb`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>, `socket`: `InstanceType`<`T`>, `request`: `InstanceType`<`U`>) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.on

Defined in

node_modules/@types/ws/index.d.ts:364

▸ on(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"error"`
`cb`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>, `error`: `Error`) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.on

Defined in

node_modules/@types/ws/index.d.ts:365

▸ on(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"headers"`
`cb`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>, `headers`: `string`[], `request`: `InstanceType`<`U`>) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.on

Defined in

node_modules/@types/ws/index.d.ts:366

▸ on(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"close"` \| `"listening"`
`cb`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.on

Defined in

node_modules/@types/ws/index.d.ts:367

▸ on(event, listener): WSServer<T, U>

Parameters

Name	Type
`event`	`string` \| `symbol`
`listener`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>, ...`args`: `any`[]) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.on

Defined in

node_modules/@types/ws/index.d.ts:368

once

▸ once(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"connection"`
`cb`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>, `socket`: `InstanceType`<`T`>, `request`: `InstanceType`<`U`>) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.once

Defined in

node_modules/@types/ws/index.d.ts:370

▸ once(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"error"`
`cb`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>, `error`: `Error`) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.once

Defined in

node_modules/@types/ws/index.d.ts:374

▸ once(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"headers"`
`cb`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>, `headers`: `string`[], `request`: `InstanceType`<`U`>) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.once

Defined in

node_modules/@types/ws/index.d.ts:375

▸ once(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"close"` \| `"listening"`
`cb`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.once

Defined in

node_modules/@types/ws/index.d.ts:376

▸ once(event, listener): WSServer<T, U>

Parameters

Name	Type
`event`	`string` \| `symbol`
`listener`	(`this`: `WSServer`<`T`, typeof `IncomingMessage`>, ...`args`: `any`[]) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.once

Defined in

node_modules/@types/ws/index.d.ts:377

prependListener

▸ prependListener(eventName, listener): WSServer<T, U>

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.

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

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

Since

v6.0.0

Parameters

Name	Type	Description
`eventName`	`string` \| `symbol`	The name of the event.
`listener`	(...`args`: `any`[]) => `void`	The callback function

Returns

WSServer<T, U>

Inherited from

EventEmitter.prependListener

Defined in

node_modules/@types/node/events.d.ts:834

prependOnceListener

▸ prependOnceListener(eventName, listener): WSServer<T, U>

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.

Since

v6.0.0

Parameters

Name	Type	Description
`eventName`	`string` \| `symbol`	The name of the event.
`listener`	(...`args`: `any`[]) => `void`	The callback function

Returns

WSServer<T, U>

Inherited from

EventEmitter.prependOnceListener

Defined in

node_modules/@types/node/events.d.ts:850

rawListeners

▸ rawListeners(eventName): 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');

Since

v9.4.0

Parameters

Name	Type
`eventName`	`string` \| `symbol`

Returns

Function[]

Inherited from

EventEmitter.rawListeners

Defined in

node_modules/@types/node/events.d.ts:766

removeAllListeners

▸ removeAllListeners(event?): WSServer<T, U>

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.

Since

v0.1.26

Parameters

Name	Type
`event?`	`string` \| `symbol`

Returns

WSServer<T, U>

Inherited from

EventEmitter.removeAllListeners

Defined in

node_modules/@types/node/events.d.ts:706

removeListener

▸ removeListener(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"connection"`
`cb`	(`client`: `InstanceType`<`T`>, `request`: `InstanceType`<`U`>) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.removeListener

Defined in

node_modules/@types/ws/index.d.ts:394

▸ removeListener(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"error"`
`cb`	(`err`: `Error`) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.removeListener

Defined in

node_modules/@types/ws/index.d.ts:395

▸ removeListener(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"headers"`
`cb`	(`headers`: `string`[], `request`: `InstanceType`<`U`>) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.removeListener

Defined in

node_modules/@types/ws/index.d.ts:396

▸ removeListener(event, cb): WSServer<T, U>

Parameters

Name	Type
`event`	`"close"` \| `"listening"`
`cb`	() => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.removeListener

Defined in

node_modules/@types/ws/index.d.ts:397

▸ removeListener(event, listener): WSServer<T, U>

Parameters

Name	Type
`event`	`string` \| `symbol`
`listener`	(...`args`: `any`[]) => `void`

Returns

WSServer<T, U>

Overrides

EventEmitter.removeListener

Defined in

node_modules/@types/ws/index.d.ts:398

setMaxListeners

▸ setMaxListeners(n): WSServer<T, U>

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.

Since

v0.3.5

Parameters

Name	Type
`n`	`number`

Returns

WSServer<T, U>

Inherited from

EventEmitter.setMaxListeners

Defined in

node_modules/@types/node/events.d.ts:716

shouldHandle

▸ shouldHandle(request): boolean | Promise<boolean>

Parameters

Name	Type
`request`	`InstanceType`<`U`>

Returns

boolean | Promise<boolean>

Defined in

node_modules/@types/ws/index.d.ts:361

addAbortListener

▸ Static addAbortListener(signal, resource): 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]();
  }
}

Since

v20.5.0

Parameters

Name	Type
`signal`	`AbortSignal`
`resource`	(`event`: `Event`) => `void`

Returns

Disposable

Disposable that removes the abort listener.

Inherited from

EventEmitter.addAbortListener

Defined in

node_modules/@types/node/events.d.ts:387

getEventListeners

▸ Static getEventListeners(emitter, name): 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] ]
}

Since

v15.2.0, v14.17.0

Parameters

Name	Type
`emitter`	`EventEmitter` \| `_DOMEventTarget`
`name`	`string` \| `symbol`

Returns

Function[]

Inherited from

EventEmitter.getEventListeners

Defined in

node_modules/@types/node/events.d.ts:308

getMaxListeners

▸ Static getMaxListeners(emitter): 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
}

Since

v19.9.0

Parameters

Name	Type
`emitter`	`EventEmitter` \| `_DOMEventTarget`

Returns

number

Inherited from

EventEmitter.getMaxListeners

Defined in

node_modules/@types/node/events.d.ts:337

listenerCount

▸ Static listenerCount(emitter, eventName): number

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

Since

v0.9.12

Deprecated

Since v3.2.0 - Use listenerCount instead.

Parameters

Name	Type	Description
`emitter`	`EventEmitter`	The emitter to query
`eventName`	`string` \| `symbol`	The event name

Returns

number

Inherited from

EventEmitter.listenerCount

Defined in

node_modules/@types/node/events.d.ts:280

on

▸ Static on(emitter, eventName, options?): AsyncIterableIterator<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());

Since

v13.6.0, v12.16.0

Parameters

Name	Type	Description
`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

Inherited from

EventEmitter.on

Defined in

node_modules/@types/node/events.d.ts:258

once

▸ Static once(emitter, eventName, options?): 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!

Since

v11.13.0, v10.16.0

Parameters

Name	Type
`emitter`	`_NodeEventTarget`
`eventName`	`string` \| `symbol`
`options?`	`StaticEventEmitterOptions`

Returns

Promise<any[]>

Inherited from

EventEmitter.once

Defined in

node_modules/@types/node/events.d.ts:193

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

Parameters

Name	Type
`emitter`	`_DOMEventTarget`
`eventName`	`string`
`options?`	`StaticEventEmitterOptions`

Returns

Promise<any[]>

Inherited from

EventEmitter.once

Defined in

node_modules/@types/node/events.d.ts:198

setMaxListeners

▸ Static setMaxListeners(n?, ...eventTargets): void

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

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

setMaxListeners(5, target, emitter);

Since

v15.4.0

Parameters

Name	Type	Description
`n?`	`number`	A non-negative number. The maximum number of listeners per `EventTarget` event.
`...eventTargets`	(`EventEmitter` \| `_DOMEventTarget`)[]	-

Returns

void

Inherited from

EventEmitter.setMaxListeners

Defined in

node_modules/@types/node/events.d.ts:352

Class: WSServer<T, U>

Type parameters

Hierarchy

Table of contents

Constructors

Properties

Methods

Constructors

constructor

Type parameters

Parameters

Overrides

Defined in

Properties

clients

Defined in

options

Defined in

path

Defined in

captureRejectionSymbol

Inherited from

Defined in

captureRejections

Inherited from

Defined in

defaultMaxListeners

Inherited from

Defined in

errorMonitor

Inherited from

Defined in

Methods

[captureRejectionSymbol]

Parameters

Returns

Inherited from

Defined in

addListener

Parameters

Returns

Overrides

Defined in

Parameters

Returns

Overrides

Defined in

Parameters

Returns

Overrides

Defined in

Parameters

Returns

Overrides

Defined in

Parameters

Returns

Overrides

Defined in

address

Returns

Defined in

close

Parameters

Returns

Defined in

emit

Parameters

Returns

Inherited from

Defined in

eventNames

Returns

Inherited from

Defined in

getMaxListeners

Returns

Inherited from

Defined in

handleUpgrade