mirror of
https://github.com/denoland/deno.git
synced 2024-11-25 15:29:32 -05:00
826 lines
26 KiB
TypeScript
826 lines
26 KiB
TypeScript
// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
|
|
// deno-lint-ignore-file no-explicit-any
|
|
|
|
// Forked from https://github.com/DefinitelyTyped/DefinitelyTyped/blob/9b9cd671114a2a5178809798d8e7f4d8ca6c2671/types/node/events.d.ts
|
|
|
|
export const captureRejectionSymbol: unique symbol;
|
|
export const defaultMaxListeners: number;
|
|
export const errorMonitor: unique symbol;
|
|
|
|
export interface Abortable {
|
|
/**
|
|
* When provided the corresponding `AbortController` can be used to cancel an asynchronous action.
|
|
*/
|
|
signal?: AbortSignal | undefined;
|
|
}
|
|
/**
|
|
* Returns a copy of the array of listeners for the event named `eventName`.
|
|
*
|
|
* For `EventEmitter`s this behaves exactly the same as calling `.listeners` on
|
|
* the emitter.
|
|
*
|
|
* For `EventTarget`s this is the only way to get the event listeners for the
|
|
* event target. This is useful for debugging and diagnostic purposes.
|
|
*
|
|
* ```js
|
|
* const { getEventListeners, EventEmitter } = require('events');
|
|
*
|
|
* {
|
|
* const ee = new EventEmitter();
|
|
* const listener = () => console.log('Events are fun');
|
|
* ee.on('foo', listener);
|
|
* getEventListeners(ee, 'foo'); // [listener]
|
|
* }
|
|
* {
|
|
* const et = new EventTarget();
|
|
* const listener = () => console.log('Events are fun');
|
|
* et.addEventListener('foo', listener);
|
|
* getEventListeners(et, 'foo'); // [listener]
|
|
* }
|
|
* ```
|
|
* @since v15.2.0
|
|
*/
|
|
export function getEventListeners(
|
|
emitter: EventTarget | EventEmitter,
|
|
name: string | symbol,
|
|
// deno-lint-ignore ban-types
|
|
): Function[];
|
|
|
|
/**
|
|
* ```js
|
|
* const { on, EventEmitter } = require('events');
|
|
*
|
|
* (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')) {
|
|
* // 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
|
|
* const { on, EventEmitter } = require('events');
|
|
* 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
|
|
* @param eventName The name of the event being listened for
|
|
* @return that iterates `eventName` events emitted by the `emitter`
|
|
*/
|
|
export function on(
|
|
emitter: EventEmitter,
|
|
eventName: string,
|
|
options?: StaticEventEmitterOptions,
|
|
): AsyncIterableIterator<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](https://dom.spec.whatwg.org/#interface-eventtarget) interface, which has no special`'error'` event
|
|
* semantics and does not listen to the `'error'` event.
|
|
*
|
|
* ```js
|
|
* const { once, EventEmitter } = require('events');
|
|
*
|
|
* async function run() {
|
|
* 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.log('error happened', err);
|
|
* }
|
|
* }
|
|
*
|
|
* run();
|
|
* ```
|
|
*
|
|
* 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
|
|
* const { EventEmitter, once } = require('events');
|
|
*
|
|
* const ee = new EventEmitter();
|
|
*
|
|
* once(ee, 'error')
|
|
* .then(([err]) => console.log('ok', err.message))
|
|
* .catch((err) => console.log('error', err.message));
|
|
*
|
|
* ee.emit('error', new Error('boom'));
|
|
*
|
|
* // Prints: ok boom
|
|
* ```
|
|
*
|
|
* An `AbortSignal` can be used to cancel waiting for the event:
|
|
*
|
|
* ```js
|
|
* const { EventEmitter, once } = require('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
|
|
*/
|
|
export function once(
|
|
emitter: NodeEventTarget,
|
|
eventName: string | symbol,
|
|
options?: StaticEventEmitterOptions,
|
|
): Promise<any[]>;
|
|
export function once(
|
|
emitter: EventTarget,
|
|
eventName: string,
|
|
options?: StaticEventEmitterOptions,
|
|
): Promise<any[]>;
|
|
|
|
/**
|
|
* `n` {number} A non-negative number. The maximum number of listeners per `EventTarget` event.
|
|
* `...eventsTargets` {EventTarget\[]|EventEmitter\[]} 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.
|
|
*/
|
|
export function setMaxListeners(n: number): EventEmitter;
|
|
|
|
/**
|
|
* A class method that returns the number of listeners for the given `eventName`registered on the given `emitter`.
|
|
*
|
|
* ```js
|
|
* const { EventEmitter, listenerCount } = require('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.
|
|
* @param emitter The emitter to query
|
|
* @param eventName The event name
|
|
*/
|
|
export function listenerCount(
|
|
emitter: EventEmitter,
|
|
eventName: string | symbol,
|
|
): number;
|
|
|
|
interface EventEmitterOptions {
|
|
/**
|
|
* Enables automatic capturing of promise rejection.
|
|
*/
|
|
captureRejections?: boolean | undefined;
|
|
}
|
|
interface NodeEventTarget {
|
|
once(eventName: string | symbol, listener: (...args: any[]) => void): this;
|
|
}
|
|
interface EventTarget {
|
|
addEventListener(
|
|
eventName: string,
|
|
listener: (...args: any[]) => void,
|
|
opts?: {
|
|
once: boolean;
|
|
},
|
|
): any;
|
|
}
|
|
interface StaticEventEmitterOptions {
|
|
signal?: AbortSignal | undefined;
|
|
}
|
|
/**
|
|
* The `EventEmitter` class is defined and exposed by the `events` module:
|
|
*
|
|
* ```js
|
|
* const EventEmitter = require('events');
|
|
* ```
|
|
*
|
|
* All `EventEmitter`s emit the event `'newListener'` when new listeners are
|
|
* added and `'removeListener'` when existing listeners are removed.
|
|
*
|
|
* It supports the following option:
|
|
* @since v0.1.26
|
|
*/
|
|
export class EventEmitter {
|
|
/**
|
|
* Alias for `emitter.on(eventName, listener)`.
|
|
* @since v0.1.26
|
|
*/
|
|
addListener(
|
|
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.
|
|
*
|
|
* ```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. The`emitter.prependListener()` method can be used as an alternative to add the
|
|
* event listener to the beginning of the listeners array.
|
|
*
|
|
* ```js
|
|
* const myEE = new EventEmitter();
|
|
* myEE.on('foo', () => console.log('a'));
|
|
* myEE.prependListener('foo', () => console.log('b'));
|
|
* myEE.emit('foo');
|
|
* // Prints:
|
|
* // b
|
|
* // a
|
|
* ```
|
|
* @since v0.1.101
|
|
* @param eventName The name of the event.
|
|
* @param listener The callback function
|
|
*/
|
|
on(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.
|
|
*
|
|
* ```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. The`emitter.prependOnceListener()` method can be used as an alternative to add the
|
|
* event listener to the beginning of the listeners array.
|
|
*
|
|
* ```js
|
|
* const myEE = new EventEmitter();
|
|
* myEE.once('foo', () => console.log('a'));
|
|
* myEE.prependOnceListener('foo', () => console.log('b'));
|
|
* myEE.emit('foo');
|
|
* // Prints:
|
|
* // b
|
|
* // a
|
|
* ```
|
|
* @since v0.3.0
|
|
* @param eventName The name of the event.
|
|
* @param listener The callback function
|
|
*/
|
|
once(eventName: string | symbol, listener: (...args: any[]) => void): this;
|
|
/**
|
|
* Removes the specified `listener` from the listener array for the event named`eventName`.
|
|
*
|
|
* ```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 any`removeListener()` or `removeAllListeners()` calls _after_ emitting and_before_ the last listener finishes execution will
|
|
* not remove them from`emit()` in progress. Subsequent events behave as expected.
|
|
*
|
|
* ```js
|
|
* 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
|
|
* 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.
|
|
* @since v0.1.26
|
|
*/
|
|
removeListener(
|
|
eventName: string | symbol,
|
|
listener: (...args: any[]) => void,
|
|
): this;
|
|
/**
|
|
* Alias for `emitter.removeListener()`.
|
|
* @since v10.0.0
|
|
*/
|
|
off(eventName: string | symbol, listener: (...args: any[]) => void): 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.
|
|
* @since v0.1.26
|
|
*/
|
|
removeAllListeners(event?: string | symbol): this;
|
|
/**
|
|
* By default `EventEmitter`s 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.
|
|
* @since v0.3.5
|
|
*/
|
|
setMaxListeners(n: number): this;
|
|
/**
|
|
* Returns the current max listener value for the `EventEmitter` which is either
|
|
* set by `emitter.setMaxListeners(n)` or defaults to {@link defaultMaxListeners}.
|
|
* @since v1.0.0
|
|
*/
|
|
getMaxListeners(): number;
|
|
/**
|
|
* 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] ]
|
|
* ```
|
|
* @since v0.1.26
|
|
*/
|
|
// deno-lint-ignore ban-types
|
|
listeners(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()`).
|
|
*
|
|
* ```js
|
|
* 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
|
|
*/
|
|
// deno-lint-ignore ban-types
|
|
rawListeners(eventName: string | symbol): Function[];
|
|
/**
|
|
* 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.
|
|
*
|
|
* ```js
|
|
* const EventEmitter = require('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
|
|
*/
|
|
emit(eventName: string | symbol, ...args: any[]): boolean;
|
|
/**
|
|
* Returns the number of listeners listening to the event named `eventName`.
|
|
* @since v3.2.0
|
|
* @param eventName The name of the event being listened for
|
|
*/
|
|
listenerCount(eventName: string | symbol): number;
|
|
/**
|
|
* 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.
|
|
*
|
|
* ```js
|
|
* server.prependListener('connection', (stream) => {
|
|
* console.log('someone connected!');
|
|
* });
|
|
* ```
|
|
*
|
|
* Returns a reference to the `EventEmitter`, so that calls can be chained.
|
|
* @since v6.0.0
|
|
* @param eventName The name of the event.
|
|
* @param listener The callback function
|
|
*/
|
|
prependListener(
|
|
eventName: string | symbol,
|
|
listener: (...args: any[]) => void,
|
|
): this;
|
|
/**
|
|
* Adds a **one-time**`listener` 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.
|
|
* @since v6.0.0
|
|
* @param eventName The name of the event.
|
|
* @param listener The callback function
|
|
*/
|
|
prependOnceListener(
|
|
eventName: string | symbol,
|
|
listener: (...args: any[]) => void,
|
|
): this;
|
|
/**
|
|
* Returns an array listing the events for which the emitter has registered
|
|
* listeners. The values in the array are strings or `Symbol`s.
|
|
*
|
|
* ```js
|
|
* const EventEmitter = require('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
|
|
*/
|
|
eventNames(): Array<string | symbol>;
|
|
|
|
constructor(options?: EventEmitterOptions);
|
|
/**
|
|
* 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](https://dom.spec.whatwg.org/#interface-eventtarget) interface, which has no special`'error'` event
|
|
* semantics and does not listen to the `'error'` event.
|
|
*
|
|
* ```js
|
|
* const { once, EventEmitter } = require('events');
|
|
*
|
|
* async function run() {
|
|
* 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.log('error happened', err);
|
|
* }
|
|
* }
|
|
*
|
|
* run();
|
|
* ```
|
|
*
|
|
* 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
|
|
* const { EventEmitter, once } = require('events');
|
|
*
|
|
* const ee = new EventEmitter();
|
|
*
|
|
* once(ee, 'error')
|
|
* .then(([err]) => console.log('ok', err.message))
|
|
* .catch((err) => console.log('error', err.message));
|
|
*
|
|
* ee.emit('error', new Error('boom'));
|
|
*
|
|
* // Prints: ok boom
|
|
* ```
|
|
*
|
|
* An `AbortSignal` can be used to cancel waiting for the event:
|
|
*
|
|
* ```js
|
|
* const { EventEmitter, once } = require('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
|
|
*/
|
|
static once(
|
|
emitter: NodeEventTarget,
|
|
eventName: string | symbol,
|
|
options?: StaticEventEmitterOptions,
|
|
): Promise<any[]>;
|
|
static once(
|
|
emitter: EventTarget,
|
|
eventName: string,
|
|
options?: StaticEventEmitterOptions,
|
|
): Promise<any[]>;
|
|
/**
|
|
* ```js
|
|
* const { on, EventEmitter } = require('events');
|
|
*
|
|
* (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')) {
|
|
* // 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
|
|
* const { on, EventEmitter } = require('events');
|
|
* 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
|
|
* @param eventName The name of the event being listened for
|
|
* @return that iterates `eventName` events emitted by the `emitter`
|
|
*/
|
|
static on: typeof on;
|
|
/**
|
|
* A class method that returns the number of listeners for the given `eventName`registered on the given `emitter`.
|
|
*
|
|
* ```js
|
|
* const { EventEmitter, listenerCount } = require('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.
|
|
* @param emitter The emitter to query
|
|
* @param eventName The event name
|
|
*/
|
|
static listenerCount(
|
|
emitter: EventEmitter,
|
|
eventName: string | symbol,
|
|
): number;
|
|
|
|
/**
|
|
* Returns a copy of the array of listeners for the event named `eventName`.
|
|
*
|
|
* For `EventEmitter`s this behaves exactly the same as calling `.listeners` on
|
|
* the emitter.
|
|
*
|
|
* For `EventTarget`s this is the only way to get the event listeners for the
|
|
* event target. This is useful for debugging and diagnostic purposes.
|
|
*
|
|
* ```js
|
|
* const { getEventListeners, EventEmitter } = require('events');
|
|
*
|
|
* {
|
|
* const ee = new EventEmitter();
|
|
* const listener = () => console.log('Events are fun');
|
|
* ee.on('foo', listener);
|
|
* getEventListeners(ee, 'foo'); // [listener]
|
|
* }
|
|
* {
|
|
* const et = new EventTarget();
|
|
* const listener = () => console.log('Events are fun');
|
|
* et.addEventListener('foo', listener);
|
|
* getEventListeners(et, 'foo'); // [listener]
|
|
* }
|
|
* ```
|
|
* @since v15.2.0
|
|
*/
|
|
static getEventListeners: typeof getEventListeners;
|
|
|
|
/**
|
|
* 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.
|
|
*/
|
|
static readonly errorMonitor: unique symbol;
|
|
static readonly captureRejectionSymbol: unique symbol;
|
|
/**
|
|
* Sets or gets the default captureRejection value for all emitters.
|
|
*/
|
|
// TODO(@bartlomieju): These should be described using static getter/setter pairs:
|
|
static captureRejections: boolean;
|
|
static defaultMaxListeners: number;
|
|
}
|
|
|
|
export default EventEmitter;
|