Skip to main content

NDJSonReader

@webda/utils

Class: NDJSonReader

Defined in: packages/utils/src/serializers.ts:67

Writable stream that parses an NDJSON stream and emits a "data" event for each parsed object.

Extends​

  • Writable

Constructors​

Constructor​

new NDJSonReader(options?): NDJSonReader

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:760

Parameters​

options?​

WritableOptions

Returns​

NDJSonReader

Inherited from​

Writable.constructor

Properties​

closed​

readonly closed: boolean

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:828

Is true after 'close' has been emitted.

Since​

v18.0.0

Inherited from​

Writable.closed

current​

current: string = ""

Defined in: packages/utils/src/serializers.ts:68

destroyed​

destroyed: boolean

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:823

Is true after writable.destroy() has been called.

Since​

v8.0.0

Inherited from​

Writable.destroyed

errored​

readonly errored: Error

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:833

Returns error if the stream has been destroyed with an error.

Since​

v18.0.0

Inherited from​

BufferWritableStream.errored

writable​

writable: boolean

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:779

Is true if it is safe to call writable.write(), which means the stream has not been destroyed, errored, or ended.

Since​

v11.4.0

Inherited from​

Writable.writable

writableAborted​

readonly writableAborted: boolean

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:784

Returns whether the stream was destroyed or errored before emitting 'finish'.

Since​

v18.0.0, v16.17.0

Inherited from​

Writable.writableAborted

writableCorked​

readonly writableCorked: number

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:818

Number of times writable.uncork() needs to be called in order to fully uncork the stream.

Since​

v13.2.0, v12.16.0

Inherited from​

Writable.writableCorked

writableEnded​

readonly writableEnded: boolean

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:790

Is true after writable.end() has been called. This property does not indicate whether the data has been flushed, for this use writable.writableFinished instead.

Since​

v12.9.0

Inherited from​

Writable.writableEnded

writableFinished​

readonly writableFinished: boolean

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:795

Is set to true immediately before the 'finish' event is emitted.

Since​

v12.6.0

Inherited from​

Writable.writableFinished

writableHighWaterMark​

readonly writableHighWaterMark: number

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:800

Return the value of highWaterMark passed when creating this Writable.

Since​

v9.3.0

Inherited from​

Writable.writableHighWaterMark

writableLength​

readonly writableLength: number

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:807

This property contains the number of bytes (or objects) in the queue ready to be written. The value provides introspection data regarding the status of the highWaterMark.

Since​

v9.4.0

Inherited from​

Writable.writableLength

writableNeedDrain​

readonly writableNeedDrain: boolean

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:838

Is true if the stream's buffer has been full and stream will emit 'drain'.

Since​

v15.2.0, v14.17.0

Inherited from​

Writable.writableNeedDrain

writableObjectMode​

readonly writableObjectMode: boolean

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:812

Getter for the property objectMode of a given Writable stream.

Since​

v12.3.0

Inherited from​

Writable.writableObjectMode

Methods​

_construct()?​

optional _construct(callback): void

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:847

Parameters​

callback​

(error?) => void

Returns​

void

Inherited from​

Writable._construct

_destroy()​

_destroy(error, callback): void

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:848

Parameters​

error​

Error

callback​

(error?) => void

Returns​

void

Inherited from​

Writable._destroy

_final()​

_final(callback): void

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:849

Parameters​

callback​

(error?) => void

Returns​

void

Inherited from​

Writable._final

_write()​

_write(chunk, encoding, callback): void

Defined in: packages/utils/src/serializers.ts:77

Buffer incoming chunks, split on newlines, and emit parsed JSON objects.

Parameters​

chunk​

any

Incoming data buffer.

encoding​

BufferEncoding

Buffer encoding (unused; data is converted to string).

callback​

(error?) => void

Call when processing is complete.

Returns​

void

Overrides​

Writable._write

_writev()?​

optional _writev(chunks, callback): void

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:840

Parameters​

chunks​

object[]

callback​

(error?) => void

Returns​

void

Inherited from​

Writable._writev

[asyncDispose]()​

[asyncDispose](): Promise<void>

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1010

Calls writable.destroy() with an AbortError and returns a promise that fulfills when the stream is finished.

Returns​

Promise<void>

Since​

v22.4.0, v20.16.0

Inherited from​

Writable.[asyncDispose]

[captureRejectionSymbol]()?​

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

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/events.d.ts:123

The Symbol.for('nodejs.rejection') method is called in case a promise rejection happens when emitting an event and captureRejections is enabled on the emitter. It is possible to use events.captureRejectionSymbol in place of Symbol.for('nodejs.rejection').

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

class MyClass extends EventEmitter {
  constructor() {
    super({ captureRejections: true });
  }

  [captureRejectionSymbol](err, event, ...args) {
    console.log('rejection happened for', event, 'with', err, ...args);
    this.destroy(err);
  }

  destroy(err) {
    // Tear the resource down here.
  }
}

Parameters​

error​

Error

event​

string | symbol

args​

...any[]

Returns​

void

Since​

v13.4.0, v12.16.0

Inherited from​

Writable.[captureRejectionSymbol]

addListener()​

Call Signature​

addListener<E>(eventName, listener): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1012

Alias for emitter.on(eventName, listener).

Type Parameters​
E​

E extends keyof WritableEventMap

Parameters​
eventName​

E

listener​

(...args) => void

Returns​

this

Since​

v0.1.26

Inherited from​

Writable.addListener

Call Signature​

addListener(eventName, listener): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1016

Parameters​
eventName​

string | symbol

listener​

(...args) => void

Returns​

this

Inherited from​

Writable.addListener

cork()​

cork(): void

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:953

The writable.cork() method forces all written data to be buffered in memory. The buffered data will be flushed when either the uncork or end methods are called.

The primary intent of writable.cork() is to accommodate a situation in which several small chunks are written to the stream in rapid succession. Instead of immediately forwarding them to the underlying destination, writable.cork() buffers all the chunks until writable.uncork() is called, which will pass them all to writable._writev(), if present. This prevents a head-of-line blocking situation where data is being buffered while waiting for the first small chunk to be processed. However, use of writable.cork() without implementing writable._writev() may have an adverse effect on throughput.

See also: writable.uncork(), writable._writev().

Returns​

void

Since​

v0.11.2

Inherited from​

Writable.cork

destroy()​

destroy(error?): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1004

Destroy the stream. Optionally emit an 'error' event, and emit a 'close' event (unless emitClose is set to false). After this call, the writable stream has ended and subsequent calls to write() or end() will result in an ERR_STREAM_DESTROYED error. This is a destructive and immediate way to destroy a stream. Previous calls to write() may not have drained, and may trigger an ERR_STREAM_DESTROYED error. Use end() instead of destroy if data should flush before close, or wait for the 'drain' event before destroying the stream.

Once destroy() has been called any further calls will be a no-op and no further errors except from _destroy() may be emitted as 'error'.

Implementors should not override this method, but instead implement writable._destroy().

Parameters​

error?​

Error

Optional, an error to emit with 'error' event.

Returns​

this

Since​

v8.0.0

Inherited from​

Writable.destroy

emit()​

Call Signature​

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

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1017

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.

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

// First listener
myEmitter.on('event', function firstListener() {
  console.log('Helloooo! first listener');
});
// Second listener
myEmitter.on('event', function secondListener(arg1, arg2) {
  console.log(`event with parameters ${arg1}, ${arg2} in second listener`);
});
// Third listener
myEmitter.on('event', function thirdListener(...args) {
  const parameters = args.join(', ');
  console.log(`event with parameters ${parameters} in third listener`);
});

console.log(myEmitter.listeners('event'));

myEmitter.emit('event', 1, 2, 3, 4, 5);

// Prints:
// [
//   [Function: firstListener],
//   [Function: secondListener],
//   [Function: thirdListener]
// ]
// Helloooo! first listener
// event with parameters 1, 2 in second listener
// event with parameters 1, 2, 3, 4, 5 in third listener
Type Parameters​
E​

E extends keyof WritableEventMap

Parameters​
eventName​

E

args​

...WritableEventMap[E]

Returns​

boolean

Since​

v0.1.26

Inherited from​

Writable.emit

Call Signature​

emit(eventName, ...args): boolean

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1018

Parameters​
eventName​

string | symbol

args​

...any[]

Returns​

boolean

Inherited from​

Writable.emit

end()​

Call Signature​

end(cb?): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:936

Calling the writable.end() method signals that no more data will be written to the Writable. The optional chunk and encoding arguments allow one final additional chunk of data to be written immediately before closing the stream.

Calling the write method after calling end will raise an error.

// Write 'hello, ' and then end with 'world!'.
import fs from 'node:fs';
const file = fs.createWriteStream('example.txt');
file.write('hello, ');
file.end('world!');
// Writing more now is not allowed!
Parameters​
cb?​

() => void

Returns​

this

Since​

v0.9.4

Inherited from​

Writable.end

Call Signature​

end(chunk, cb?): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:937

Calling the writable.end() method signals that no more data will be written to the Writable. The optional chunk and encoding arguments allow one final additional chunk of data to be written immediately before closing the stream.

Calling the write method after calling end will raise an error.

// Write 'hello, ' and then end with 'world!'.
import fs from 'node:fs';
const file = fs.createWriteStream('example.txt');
file.write('hello, ');
file.end('world!');
// Writing more now is not allowed!
Parameters​
chunk​

any

Optional data to write. For streams not operating in object mode, chunk must be a {string}, {Buffer}, {TypedArray} or {DataView}. For object mode streams, chunk may be any JavaScript value other than null.

cb?​

() => void

Returns​

this

Since​

v0.9.4

Inherited from​

Writable.end

Call Signature​

end(chunk, encoding, cb?): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:938

Calling the writable.end() method signals that no more data will be written to the Writable. The optional chunk and encoding arguments allow one final additional chunk of data to be written immediately before closing the stream.

Calling the write method after calling end will raise an error.

// Write 'hello, ' and then end with 'world!'.
import fs from 'node:fs';
const file = fs.createWriteStream('example.txt');
file.write('hello, ');
file.end('world!');
// Writing more now is not allowed!
Parameters​
chunk​

any

Optional data to write. For streams not operating in object mode, chunk must be a {string}, {Buffer}, {TypedArray} or {DataView}. For object mode streams, chunk may be any JavaScript value other than null.

encoding​

BufferEncoding

The encoding if chunk is a string

cb?​

() => void

Returns​

this

Since​

v0.9.4

Inherited from​

Writable.end

eventNames()​

eventNames(): (string | symbol)[]

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/events.d.ts:190

Returns an array listing the events for which the emitter has registered listeners.

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​

Writable.eventNames

getMaxListeners()​

getMaxListeners(): number

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/events.d.ts:197

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

Returns​

number

Since​

v1.0.0

Inherited from​

Writable.getMaxListeners

listenerCount()​

Call Signature​

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

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1019

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​
E​

E extends keyof WritableEventMap

Parameters​
eventName​

E

The name of the event being listened for

listener?​

(...args) => void

The event handler function

Returns​

number

Since​

v3.2.0

Inherited from​

Writable.listenerCount

Call Signature​

listenerCount(eventName, listener?): number

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1023

Parameters​
eventName​

string | symbol

listener?​

(...args) => void

Returns​

number

Inherited from​

Writable.listenerCount

listeners()​

Call Signature​

listeners<E>(eventName): (...args) => void[]

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1024

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​
E​

E extends keyof WritableEventMap

Parameters​
eventName​

E

Returns​

(...args) => void[]

Since​

v0.1.26

Inherited from​

Writable.listeners

Call Signature​

listeners(eventName): (...args) => void[]

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1025

Parameters​
eventName​

string | symbol

Returns​

(...args) => void[]

Inherited from​

Writable.listeners

off()​

Call Signature​

off<E>(eventName, listener): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1026

Alias for emitter.removeListener().

Type Parameters​
E​

E extends keyof WritableEventMap

Parameters​
eventName​

E

listener​

(...args) => void

Returns​

this

Since​

v10.0.0

Inherited from​

Writable.off

Call Signature​

off(eventName, listener): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1027

Parameters​
eventName​

string | symbol

listener​

(...args) => void

Returns​

this

Inherited from​

Writable.off

on()​

Call Signature​

on<E>(eventName, listener): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1028

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.

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.

import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => console.log('a'));
myEE.prependListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
//   b
//   a
Type Parameters​
E​

E extends keyof WritableEventMap

Parameters​
eventName​

E

The name of the event.

listener​

(...args) => void

The callback function

Returns​

this

Since​

v0.1.101

Inherited from​

Writable.on

Call Signature​

on(eventName, listener): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1029

Parameters​
eventName​

string | symbol

listener​

(...args) => void

Returns​

this

Inherited from​

Writable.on

once()​

Call Signature​

once<E>(eventName, listener): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1030

Adds a one-time listener 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. The emitter.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
Type Parameters​
E​

E extends keyof WritableEventMap

Parameters​
eventName​

E

The name of the event.

listener​

(...args) => void

The callback function

Returns​

this

Since​

v0.3.0

Inherited from​

Writable.once

Call Signature​

once(eventName, listener): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1034

Parameters​
eventName​

string | symbol

listener​

(...args) => void

Returns​

this

Inherited from​

Writable.once

pipe()​

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

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:29

Type Parameters​

T​

T extends WritableStream

Parameters​

destination​

T

options?​

PipeOptions

Returns​

T

Since​

v0.9.4

Inherited from​

Writable.pipe

prependListener()​

Call Signature​

prependListener<E>(eventName, listener): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1035

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​
E​

E extends keyof WritableEventMap

Parameters​
eventName​

E

The name of the event.

listener​

(...args) => void

The callback function

Returns​

this

Since​

v6.0.0

Inherited from​

Writable.prependListener

Call Signature​

prependListener(eventName, listener): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1039

Parameters​
eventName​

string | symbol

listener​

(...args) => void

Returns​

this

Inherited from​

Writable.prependListener

prependOnceListener()​

Call Signature​

prependOnceListener<E>(eventName, listener): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1040

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.

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​
E​

E extends keyof WritableEventMap

Parameters​
eventName​

E

The name of the event.

listener​

(...args) => void

The callback function

Returns​

this

Since​

v6.0.0

Inherited from​

Writable.prependOnceListener

Call Signature​

prependOnceListener(eventName, listener): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1044

Parameters​
eventName​

string | symbol

listener​

(...args) => void

Returns​

this

Inherited from​

Writable.prependOnceListener

rawListeners()​

Call Signature​

rawListeners<E>(eventName): (...args) => void[]

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1045

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​
E​

E extends keyof WritableEventMap

Parameters​
eventName​

E

Returns​

(...args) => void[]

Since​

v9.4.0

Inherited from​

Writable.rawListeners

Call Signature​

rawListeners(eventName): (...args) => void[]

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1046

Parameters​
eventName​

string | symbol

Returns​

(...args) => void[]

Inherited from​

Writable.rawListeners

removeAllListeners()​

Call Signature​

removeAllListeners<E>(eventName?): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1048

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.

Type Parameters​
E​

E extends keyof WritableEventMap

Parameters​
eventName?​

E

Returns​

this

Since​

v0.1.26

Inherited from​

Writable.removeAllListeners

Call Signature​

removeAllListeners(eventName?): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1049

Parameters​
eventName?​

string | symbol

Returns​

this

Inherited from​

Writable.removeAllListeners

removeListener()​

Call Signature​

removeListener<E>(eventName, listener): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1050

Removes the specified listener from the listener array for the event named eventName.

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.

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 indexes 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.

Type Parameters​
E​

E extends keyof WritableEventMap

Parameters​
eventName​

E

listener​

(...args) => void

Returns​

this

Since​

v0.1.26

Inherited from​

Writable.removeListener

Call Signature​

removeListener(eventName, listener): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:1054

Parameters​
eventName​

string | symbol

listener​

(...args) => void

Returns​

this

Inherited from​

Writable.removeListener

setDefaultEncoding()​

setDefaultEncoding(encoding): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:913

The writable.setDefaultEncoding() method sets the default encoding for a Writable stream.

Parameters​

encoding​

BufferEncoding

The new default encoding

Returns​

this

Since​

v0.11.15

Inherited from​

Writable.setDefaultEncoding

setMaxListeners()​

setMaxListeners(n): this

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/events.d.ts:472

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​

n​

number

Returns​

this

Since​

v0.3.5

Inherited from​

Writable.setMaxListeners

uncork()​

uncork(): void

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:987

The writable.uncork() method flushes all data buffered since cork was called.

When using writable.cork() and writable.uncork() to manage the buffering of writes to a stream, defer calls to writable.uncork() using process.nextTick(). Doing so allows batching of all writable.write() calls that occur within a given Node.js event loop phase.

stream.cork();
stream.write('some ');
stream.write('data ');
process.nextTick(() => stream.uncork());

If the writable.cork() method is called multiple times on a stream, the same number of calls to writable.uncork() must be called to flush the buffered data.

stream.cork();
stream.write('some ');
stream.cork();
stream.write('data ');
process.nextTick(() => {
  stream.uncork();
  // The data will not be flushed until uncork() is called a second time.
  stream.uncork();
});

See also: writable.cork().

Returns​

void

Since​

v0.11.2

Inherited from​

Writable.uncork

write()​

Call Signature​

write(chunk, callback?): boolean

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:906

The writable.write() method writes some data to the stream, and calls the supplied callback once the data has been fully handled. If an error occurs, the callback will be called with the error as its first argument. The callback is called asynchronously and before 'error' is emitted.

The return value is true if the internal buffer is less than the highWaterMark configured when the stream was created after admitting chunk. If false is returned, further attempts to write data to the stream should stop until the 'drain' event is emitted.

While a stream is not draining, calls to write() will buffer chunk, and return false. Once all currently buffered chunks are drained (accepted for delivery by the operating system), the 'drain' event will be emitted. Once write() returns false, do not write more chunks until the 'drain' event is emitted. While calling write() on a stream that is not draining is allowed, Node.js will buffer all written chunks until maximum memory usage occurs, at which point it will abort unconditionally. Even before it aborts, high memory usage will cause poor garbage collector performance and high RSS (which is not typically released back to the system, even after the memory is no longer required). Since TCP sockets may never drain if the remote peer does not read the data, writing a socket that is not draining may lead to a remotely exploitable vulnerability.

Writing data while the stream is not draining is particularly problematic for a Transform, because the Transform streams are paused by default until they are piped or a 'data' or 'readable' event handler is added.

If the data to be written can be generated or fetched on demand, it is recommended to encapsulate the logic into a Readable and use pipe. However, if calling write() is preferred, it is possible to respect backpressure and avoid memory issues using the 'drain' event:

function write(data, cb) {
  if (!stream.write(data)) {
    stream.once('drain', cb);
  } else {
    process.nextTick(cb);
  }
}

// Wait for cb to be called before doing any other write.
write('hello', () => {
  console.log('Write completed, do more writes now.');
});

A Writable stream in object mode will always ignore the encoding argument.

Parameters​
chunk​

any

Optional data to write. For streams not operating in object mode, chunk must be a {string}, {Buffer}, {TypedArray} or {DataView}. For object mode streams, chunk may be any JavaScript value other than null.

callback?​

(error) => void

Callback for when this chunk of data is flushed.

Returns​

boolean

false if the stream wishes for the calling code to wait for the 'drain' event to be emitted before continuing to write additional data; otherwise true.

Since​

v0.9.4

Inherited from​

Writable.write

Call Signature​

write(chunk, encoding, callback?): boolean

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:907

The writable.write() method writes some data to the stream, and calls the supplied callback once the data has been fully handled. If an error occurs, the callback will be called with the error as its first argument. The callback is called asynchronously and before 'error' is emitted.

The return value is true if the internal buffer is less than the highWaterMark configured when the stream was created after admitting chunk. If false is returned, further attempts to write data to the stream should stop until the 'drain' event is emitted.

While a stream is not draining, calls to write() will buffer chunk, and return false. Once all currently buffered chunks are drained (accepted for delivery by the operating system), the 'drain' event will be emitted. Once write() returns false, do not write more chunks until the 'drain' event is emitted. While calling write() on a stream that is not draining is allowed, Node.js will buffer all written chunks until maximum memory usage occurs, at which point it will abort unconditionally. Even before it aborts, high memory usage will cause poor garbage collector performance and high RSS (which is not typically released back to the system, even after the memory is no longer required). Since TCP sockets may never drain if the remote peer does not read the data, writing a socket that is not draining may lead to a remotely exploitable vulnerability.

Writing data while the stream is not draining is particularly problematic for a Transform, because the Transform streams are paused by default until they are piped or a 'data' or 'readable' event handler is added.

If the data to be written can be generated or fetched on demand, it is recommended to encapsulate the logic into a Readable and use pipe. However, if calling write() is preferred, it is possible to respect backpressure and avoid memory issues using the 'drain' event:

function write(data, cb) {
  if (!stream.write(data)) {
    stream.once('drain', cb);
  } else {
    process.nextTick(cb);
  }
}

// Wait for cb to be called before doing any other write.
write('hello', () => {
  console.log('Write completed, do more writes now.');
});

A Writable stream in object mode will always ignore the encoding argument.

Parameters​
chunk​

any

Optional data to write. For streams not operating in object mode, chunk must be a {string}, {Buffer}, {TypedArray} or {DataView}. For object mode streams, chunk may be any JavaScript value other than null.

encoding​

BufferEncoding

The encoding, if chunk is a string.

callback?​

(error) => void

Callback for when this chunk of data is flushed.

Returns​

boolean

false if the stream wishes for the calling code to wait for the 'drain' event to be emitted before continuing to write additional data; otherwise true.

Since​

v0.9.4

Inherited from​

Writable.write

fromWeb()​

static fromWeb(writableStream, options?): Writable

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:765

A utility method for creating a Writable from a web WritableStream.

Parameters​

writableStream​

WritableStream

options?​

Pick<WritableOptions, "decodeStrings" | "highWaterMark" | "objectMode" | "signal">

Returns​

Writable

Since​

v17.0.0

Inherited from​

Writable.fromWeb

toWeb()​

static toWeb(streamWritable): WritableStream

Defined in: node_modules/.pnpm/@types+node@25.5.0/node_modules/@types/node/stream.d.ts:773

A utility method for creating a web WritableStream from a Writable.

Parameters​

streamWritable​

WritableStream

Returns​

WritableStream

Since​

v17.0.0

Inherited from​

Writable.toWeb