ReadWriteStream

admin/discounts.internal.ReadWriteStream

Properties

readablebooleanRequired

writablebooleanRequired

Methods

[asyncIterator]

[asyncIterator](): AsyncIterableIterator<string | Buffer>

Returns

AsyncIterableIterator<string | Buffer>

AsyncIterableIteratorAsyncIterableIterator<string | Buffer>Required

Inherited from

ReadableStream.[asyncIterator]

---

addListener

addListener(eventName, listener): ReadWriteStream

Alias for emitter.on(eventName, listener).

Parameters

eventNamestring | symbolRequired

listener(...args: any[]) => voidRequired

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Since

v0.1.26

Inherited from

WritableStream.addListener

---

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

Parameters

eventNamestring | symbolRequired

argsany[]Required

Returns

boolean

booleanboolean

Since

v0.1.26

Inherited from

WritableStream.emit

---

end

end(cb?): ReadWriteStream

Parameters

cb() => void

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Inherited from

WritableStream.end

end(data, cb?): ReadWriteStream

Parameters

datastring | Uint8ArrayRequired

cb() => void

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Inherited from

WritableStream.end

end(str, encoding?, cb?): ReadWriteStream

Parameters

strstringRequired

encodingBufferEncoding

cb() => void

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Inherited from

WritableStream.end

---

eventNames

eventNames(): (string | symbol)[]

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

import { EventEmitter } from 'node:events';

const myEE = new EventEmitter();
myEE.on('foo', () => {});
myEE.on('bar', () => {});

const sym = Symbol('symbol');
myEE.on(sym, () => {});

console.log(myEE.eventNames());
// Prints: [ 'foo', 'bar', Symbol(symbol) ]

Returns

(string | symbol)[]

(string \| symbol)[](string | symbol)[]Required

Since

v6.0.0

Inherited from

WritableStream.eventNames

---

getMaxListeners

getMaxListeners(): number

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

Returns

number

numbernumber

Since

v1.0.0

Inherited from

WritableStream.getMaxListeners

---

isPaused

isPaused(): boolean

Returns

boolean

booleanboolean

Inherited from

ReadableStream.isPaused

---

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.

Parameters

eventNamestring | symbolRequired

The name of the event being listened for

listenerFunction

The event handler function

Returns

number

numbernumber

Since

v3.2.0

Inherited from

WritableStream.listenerCount

---

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] ]

Parameters

eventNamestring | symbolRequired

Returns

Function[]

Function[]Function[]Required

Since

v0.1.26

Inherited from

WritableStream.listeners

---

off

off(eventName, listener): ReadWriteStream

Alias for emitter.removeListener().

Parameters

eventNamestring | symbolRequired

listener(...args: any[]) => voidRequired

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Since

v10.0.0

Inherited from

WritableStream.off

---

on

on(eventName, listener): ReadWriteStream

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.

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.

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

Parameters

eventNamestring | symbolRequired

The name of the event.

listener(...args: any[]) => voidRequired

The callback function

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Since

v0.1.101

Inherited from

WritableStream.on

---

once

once(eventName, listener): ReadWriteStream

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

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

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

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

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

Parameters

eventNamestring | symbolRequired

The name of the event.

listener(...args: any[]) => voidRequired

The callback function

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Since

v0.3.0

Inherited from

WritableStream.once

---

pause

pause(): ReadWriteStream

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Inherited from

ReadableStream.pause

---

pipe

pipe<T>(destination, options?): T

TWritableStreamRequired

Parameters

destinationTRequired

optionsobject

options.endboolean

Returns

T

Inherited from

ReadableStream.pipe

---

prependListener

prependListener(eventName, listener): ReadWriteStream

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.

Parameters

eventNamestring | symbolRequired

The name of the event.

listener(...args: any[]) => voidRequired

The callback function

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Since

v6.0.0

Inherited from

WritableStream.prependListener

---

prependOnceListener

prependOnceListener(eventName, listener): ReadWriteStream

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.

Parameters

eventNamestring | symbolRequired

The name of the event.

listener(...args: any[]) => voidRequired

The callback function

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Since

v6.0.0

Inherited from

WritableStream.prependOnceListener

---

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');

Parameters

eventNamestring | symbolRequired

Returns

Function[]

Function[]Function[]Required

Since

v9.4.0

Inherited from

WritableStream.rawListeners

---

read

read(size?): string | Buffer

Parameters

sizenumber

Returns

string | Buffer

string \| Bufferstring | Buffer

Inherited from

ReadableStream.read

---

removeAllListeners

removeAllListeners(event?): ReadWriteStream

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

eventstring | symbol

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Since

v0.1.26

Inherited from

WritableStream.removeAllListeners

---

removeListener

removeListener(eventName, listener): ReadWriteStream

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

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.

import { EventEmitter } from 'node:events';
class MyEmitter extends EventEmitter {}
const myEmitter = new MyEmitter();

const callbackA = () => {
  console.log('A');
  myEmitter.removeListener('event', callbackB);
};

const callbackB = () => {
  console.log('B');
};

myEmitter.on('event', callbackA);

myEmitter.on('event', callbackB);

// callbackA removes listener callbackB but it will still be called.
// Internal listener array at time of emit [callbackA, callbackB]
myEmitter.emit('event');
// Prints:
//   A
//   B

// callbackB is now removed.
// Internal listener array [callbackA]
myEmitter.emit('event');
// Prints:
//   A

Because listeners are managed using an internal array, calling this will change the position indices of any listener registered after the listener being removed. This will not impact the order in which listeners are called, but it means that any copies of the listener array as returned by the emitter.listeners() method will need to be recreated.

When a single function has been added as a handler multiple times for a single event (as in the example below), removeListener() will remove the most recently added instance. In the example the once('ping')listener is removed:

import { EventEmitter } from 'node:events';
const ee = new EventEmitter();

function pong() {
  console.log('pong');
}

ee.on('ping', pong);
ee.once('ping', pong);
ee.removeListener('ping', pong);

ee.emit('ping');
ee.emit('ping');

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

Parameters

eventNamestring | symbolRequired

listener(...args: any[]) => voidRequired

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Since

v0.1.26

Inherited from

WritableStream.removeListener

---

resume

resume(): ReadWriteStream

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Inherited from

ReadableStream.resume

---

setEncoding

setEncoding(encoding): ReadWriteStream

Parameters

encodingBufferEncodingRequired

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Inherited from

ReadableStream.setEncoding

---

setMaxListeners

setMaxListeners(n): ReadWriteStream

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

nnumberRequired

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Since

v0.3.5

Inherited from

WritableStream.setMaxListeners

---

unpipe

unpipe(destination?): ReadWriteStream

Parameters

destinationWritableStream

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Inherited from

ReadableStream.unpipe

---

unshift

unshift(chunk, encoding?): void

Parameters

chunkstring | Uint8ArrayRequired

encodingBufferEncoding

Returns

void

voidvoid

Inherited from

ReadableStream.unshift

---

wrap

wrap(oldStream): ReadWriteStream

Parameters

oldStreamReadableStreamRequired

Returns

ReadWriteStream

ReadWriteStreamReadWriteStreamRequired

Inherited from

ReadableStream.wrap

---

write

write(buffer, cb?): boolean

Parameters

bufferstring | Uint8ArrayRequired

cb(err?: null | Error) => void

Returns

boolean

booleanboolean

Inherited from

WritableStream.write

write(str, encoding?, cb?): boolean

Parameters

strstringRequired

encodingBufferEncoding

cb(err?: null | Error) => void

Returns

boolean

booleanboolean

Inherited from

WritableStream.write