NodeManager

Defined in: src/structures/NodeManager.ts:10

Extends

EventEmitter

Constructors

Constructor

new NodeManager(LavalinkManager: LavalinkManager): NodeManager;

Defined in: src/structures/NodeManager.ts:73

Parameters

Parameter	Type	Description
`LavalinkManager`	`LavalinkManager`	The LavalinkManager that created this NodeManager

Returns

NodeManager

Overrides

EventEmitter.constructor

Properties

Property (defined in)	Type	Description
`LavalinkManager` (src/structures/NodeManager.ts:64)	`LavalinkManager`	The LavalinkManager that created this NodeManager
`nodes` (A map of all nodes in the nodeManager)	`MiniMap`<`string`, \	`LavalinkNode` \
`captureRejections` (node_modules/@types/node/events.d.ts:425)	`boolean`	Value: boolean Change the default `captureRejections` option on all new `EventEmitter` objects. Since v13.4…
`captureRejectionSymbol` (node_modules/@types/node/events.d.ts:418)	typeof `captureRejectionSymbol`	Value: `Symbol.for('nodejs.rejection')` See how to write a custom `rejection handler`. Since v13.4.0, v12.16.0
`defaultMaxListeners` (node_modules/@types/node/events.d.ts:464)	`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 chan…
`errorMonitor` (node_modules/@types/node/events.d.ts:411)	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 l…

Methods

[captureRejectionSymbol]()?

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

Defined in: node_modules/@types/node/events.d.ts:103

Type Parameters

Type Parameter
`K`

Parameters

Parameter	Type
`error`	`Error`
`event`	`string` \| `symbol`
…`args`	`AnyRest`

Returns

void

Inherited from

EventEmitter.[captureRejectionSymbol]

addListener()

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

Defined in: node_modules/@types/node/events.d.ts:642

Alias for emitter.on(eventName, listener).

Type Parameters

Type Parameter
`K`

Parameters

Parameter	Type
`eventName`	`string` \| `symbol`
`listener`	(…`args`: `any`[]) => `void`

Returns

this

Since

v0.1.26

Inherited from

EventEmitter.addListener

connectAll()

connectAll(): Promise<number>;

Defined in: src/structures/NodeManager.ts:110

Connects all not connected nodes

Returns

Promise<number>

Amount of connected Nodes

createNode()

createNode<T>(options: LavalinkNodeOptions): T;

Defined in: src/structures/NodeManager.ts:144

Create a node and add it to the nodeManager

Type Parameters

Type Parameter
`T` extends \| `LavalinkNode` \| `NodeLinkNode`

Parameters

Parameter	Type	Description
`options`	`LavalinkNodeOptions`	The options for the node

Returns

T

The node that was created

deleteNode()

deleteNode(node:
  | string
  | LavalinkNode
  | NodeLinkNode, movePlayers?: boolean): void;

Defined in: src/structures/NodeManager.ts:223

Delete a node from the nodeManager and destroy it

Parameters

Parameter	Type	Default value	Description
`node`	\| `string` \| `LavalinkNode` \| `NodeLinkNode`	`undefined`	The node to delete
`movePlayers`	`boolean`	`false`	whether to movePlayers to different connected node before deletion.

Returns

void

Default

false

Example

Deletes the node

client.lavalink.nodeManager.deleteNode("nodeId to delete");

Moves players to a different node before deleting

client.lavalink.nodeManager.deleteNode("nodeId to delete", true);

disconnectAll()

disconnectAll(deleteAllNodes?: boolean, destroyPlayers?: boolean): Promise<number>;

Defined in: src/structures/NodeManager.ts:89

Disconnects all Nodes from lavalink ws sockets

Parameters

Parameter	Type	Default value	Description
`deleteAllNodes`	`boolean`	`false`	if the nodes should also be deleted from nodeManager.nodes
`destroyPlayers`	`boolean`	`true`	if the players should be destroyed

Returns

Promise<number>

amount of disconnected Nodes

emit()

emit<Event>(event: Event, ...args: Parameters<NodeManagerEvents[Event]>): boolean;

Defined in: src/structures/NodeManager.ts:17

Emit an event

Type Parameters

Type Parameter
`Event` extends keyof `NodeManagerEvents`

Parameters

Parameter	Type	Description
`event`	`Event`	The event to emit
…`args`	`Parameters`<`NodeManagerEvents`[`Event`]>	The arguments to pass to the event

Returns

boolean

Overrides

EventEmitter.emit

eventNames()

eventNames(): (string | symbol)[];

Defined in: node_modules/@types/node/events.d.ts:967

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

Inherited from

EventEmitter.eventNames

getMaxListeners()

getMaxListeners(): number;

Defined in: node_modules/@types/node/events.d.ts:819

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

Inherited from

EventEmitter.getMaxListeners

getNode()

getNode(node:
  | string
  | LavalinkNode
  | NodeLinkNode):
  | LavalinkNode
  | NodeLinkNode;

Defined in: src/structures/NodeManager.ts:239

Get a node from the nodeManager

Parameters

Parameter	Type	Description
`node`	\| `string` \| `LavalinkNode` \| `NodeLinkNode`	The node to get

Returns

| LavalinkNode | NodeLinkNode

The node that was retrieved

leastUsedNodes()

leastUsedNodes(sortType?:
  | "memory"
  | "cpuLavalink"
  | "cpuSystem"
  | "calls"
  | "playingPlayers"
  | "players"): LavalinkNode[];

Defined in: src/structures/NodeManager.ts:158

Get the nodes sorted for the least usage, by a sorttype

Parameters

Parameter	Type	Default value	Description
`sortType`	\| `"memory"` \| `"cpuLavalink"` \| `"cpuSystem"` \| `"calls"` \| `"playingPlayers"` \| `"players"`	`"players"`	The type of sorting to use

Returns

LavalinkNode[]

listenerCount()

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

Defined in: node_modules/@types/node/events.d.ts:913

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

Type Parameter
`K`

Parameters

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

Returns

number

Since

v3.2.0

Inherited from

EventEmitter.listenerCount

listeners()

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

Defined in: node_modules/@types/node/events.d.ts:832

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

Type Parameter
`K`

Parameters

Parameter	Type
`eventName`	`string` \| `symbol`

Returns

Function[]

Since

v0.1.26

Inherited from

EventEmitter.listeners

off()

off<Event>(event: Event, listener: NodeManagerEvents[Event]): this;

Defined in: src/structures/NodeManager.ts:47

Remove an event listener

Type Parameters

Type Parameter
`Event` extends keyof `NodeManagerEvents`

Parameters

Parameter	Type	Description
`event`	`Event`	The event to remove the listener from
`listener`	`NodeManagerEvents`[`Event`]	The listener to remove

Returns

this

Overrides

EventEmitter.off

on()

on<Event>(event: Event, listener: NodeManagerEvents[Event]): this;

Defined in: src/structures/NodeManager.ts:27

Add an event listener

Type Parameters

Type Parameter
`Event` extends keyof `NodeManagerEvents`

Parameters

Parameter	Type	Description
`event`	`Event`	The event to listen to
`listener`	`NodeManagerEvents`[`Event`]	The listener to add

Returns

this

Overrides

EventEmitter.on

once()

once<Event>(event: Event, listener: NodeManagerEvents[Event]): this;

Defined in: src/structures/NodeManager.ts:37

Add an event listener that only fires once

Type Parameters

Type Parameter
`Event` extends keyof `NodeManagerEvents`

Parameters

Parameter	Type	Description
`event`	`Event`	The event to listen to
`listener`	`NodeManagerEvents`[`Event`]	The listener to add

Returns

this

Overrides

EventEmitter.once

prependListener()

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

Defined in: node_modules/@types/node/events.d.ts:931

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

Type Parameter
`K`

Parameters

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

Returns

this

Since

v6.0.0

Inherited from

EventEmitter.prependListener

prependOnceListener()

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

Defined in: node_modules/@types/node/events.d.ts:947

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

Type Parameter
`K`

Parameters

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

Returns

this

Since

v6.0.0

Inherited from

EventEmitter.prependOnceListener

rawListeners()

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

Defined in: node_modules/@types/node/events.d.ts:863

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

Type Parameter
`K`

Parameters

Parameter	Type
`eventName`	`string` \| `symbol`

Returns

Function[]

Since

v9.4.0

Inherited from

EventEmitter.rawListeners

reconnectAll()

reconnectAll(): Promise<number>;

Defined in: src/structures/NodeManager.ts:127

Forcefully reconnects all nodes

Returns

Promise<number>

amount of nodes

removeAllListeners()

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

Defined in: node_modules/@types/node/events.d.ts:803

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

Parameter	Type
`eventName?`	`string` \| `symbol`

Returns

this

Since

v0.1.26

Inherited from

EventEmitter.removeAllListeners

removeListener()

removeListener<Event>(event: Event, listener: NodeManagerEvents[Event]): this;

Defined in: src/structures/NodeManager.ts:57

Remove an event listener

Type Parameters

Type Parameter
`Event` extends keyof `NodeManagerEvents`

Parameters

Parameter	Type	Description
`event`	`Event`	The event to remove the listener from
`listener`	`NodeManagerEvents`[`Event`]	The listener to remove

Returns

this

Overrides

EventEmitter.removeListener

setMaxListeners()

setMaxListeners(n: number): this;

Defined in: node_modules/@types/node/events.d.ts:813

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

Parameter	Type
`n`	`number`

Returns

this

Since

v0.3.5

Inherited from

EventEmitter.setMaxListeners

addAbortListener()

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

Defined in: node_modules/@types/node/events.d.ts:403

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

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

Returns

Disposable

Disposable that removes the abort listener.

Since

v20.5.0

Inherited from

EventEmitter.addAbortListener

getEventListeners()

static getEventListeners(emitter: EventEmitter<DefaultEventMap> | EventTarget, name: string | symbol): 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.

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

Parameter	Type
`emitter`	`EventEmitter`<`DefaultEventMap`> \| `EventTarget`
`name`	`string` \| `symbol`

Returns

Function[]

Since

v15.2.0, v14.17.0

Inherited from

EventEmitter.getEventListeners

getMaxListeners()

static getMaxListeners(emitter: EventEmitter<DefaultEventMap> | EventTarget): 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.

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

Parameter	Type
`emitter`	`EventEmitter`<`DefaultEventMap`> \| `EventTarget`

Returns

number

Since

v19.9.0

Inherited from

EventEmitter.getMaxListeners

listenerCount()

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

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

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

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

Returns

number

Since

v0.9.12

Inherited from

EventEmitter.listenerCount

on()

Call Signature

static on(
   emitter: EventEmitter,
   eventName: string | symbol,
options?: StaticEventEmitterIteratorOptions): AsyncIterator<any[]>;

Defined in: node_modules/@types/node/events.d.ts:270

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

Parameter	Type
`emitter`	`EventEmitter`
`eventName`	`string` \| `symbol`
`options?`	`StaticEventEmitterIteratorOptions`

Returns

AsyncIterator<any[]>

An AsyncIterator that iterates eventName events emitted by the emitter

Since

v13.6.0, v12.16.0

Inherited from

EventEmitter.on

Call Signature

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

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

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

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

Parameter	Type
`emitter`	`EventTarget`
`eventName`	`string`
`options?`	`StaticEventEmitterIteratorOptions`

Returns

AsyncIterator<any[]>

An AsyncIterator 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: EventEmitter,
   eventName: string | symbol,
options?: StaticEventEmitterOptions): Promise<any[]>;

Defined in: node_modules/@types/node/events.d.ts:184

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

Parameter	Type
`emitter`	`EventEmitter`
`eventName`	`string` \| `symbol`
`options?`	`StaticEventEmitterOptions`

Returns

Promise<any[]>

Since

v11.13.0, v10.16.0

Inherited from

EventEmitter.once

Call Signature

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

Defined in: node_modules/@types/node/events.d.ts:189

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);
}

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

Parameter	Type
`emitter`	`EventTarget`
`eventName`	`string`
`options?`	`StaticEventEmitterOptions`

Returns

Promise<any[]>

Since

v11.13.0, v10.16.0

Inherited from

EventEmitter.once

setMaxListeners()

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

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

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

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

setMaxListeners(5, target, emitter);

Parameters

Parameter	Type	Description
`n?`	`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

Inherited from

EventEmitter.setMaxListeners