Skip to main content

@webda/core • Readme | API

Class: NDJSONStream

NDJSONStream is a Readable stream that emits JSON objects separated by newlines.

Extends​

  • Readable

Constructors​

new NDJSONStream(data)​

new NDJSONStream(data): NDJSONStream

Parameters​

• data: any[]

Returns​

NDJSONStream

Overrides​

Readable.constructor

Source​

packages/core/src/utils/serializers.ts:34

Properties​

closed​

readonly closed: boolean

Is true after 'close' has been emitted.

Since​

v18.0.0

Inherited from​

Readable.closed

Source​

packages/core/node_modules/@types/node/stream.d.ts:134

destroyed​

destroyed: boolean

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

Since​

v8.0.0

Inherited from​

Readable.destroyed

Source​

packages/core/node_modules/@types/node/stream.d.ts:129

errored​

readonly errored: Error

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

Since​

v18.0.0

Inherited from​

Readable.errored

Source​

packages/core/node_modules/@types/node/stream.d.ts:139

readable​

readable: boolean

Is true if it is safe to call readable.read(), which means the stream has not been destroyed or emitted 'error' or 'end'.

Since​

v11.4.0

Inherited from​

Readable.readable

Source​

packages/core/node_modules/@types/node/stream.d.ts:85

readableAborted​

Experimental

readonly readableAborted: boolean

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

Since​

v16.8.0

Inherited from​

Readable.readableAborted

Source​

packages/core/node_modules/@types/node/stream.d.ts:79

readableDidRead​

Experimental

readonly readableDidRead: boolean

Returns whether 'data' has been emitted.

Since​

v16.7.0, v14.18.0

Inherited from​

Readable.readableDidRead

Source​

packages/core/node_modules/@types/node/stream.d.ts:91

readableEncoding​

readonly readableEncoding: BufferEncoding

Getter for the property encoding of a given Readable stream. The encodingproperty can be set using the readable.setEncoding() method.

Since​

v12.7.0

Inherited from​

Readable.readableEncoding

Source​

packages/core/node_modules/@types/node/stream.d.ts:96

readableEnded​

readonly readableEnded: boolean

Becomes true when 'end' event is emitted.

Since​

v12.9.0

Inherited from​

Readable.readableEnded

Source​

packages/core/node_modules/@types/node/stream.d.ts:101

readableFlowing​

readonly readableFlowing: boolean

This property reflects the current state of a Readable stream as described in the Three states section.

Since​

v9.4.0

Inherited from​

Readable.readableFlowing

Source​

packages/core/node_modules/@types/node/stream.d.ts:107

readableHighWaterMark​

readonly readableHighWaterMark: number

Returns the value of highWaterMark passed when creating this Readable.

Since​

v9.3.0

Inherited from​

Readable.readableHighWaterMark

Source​

packages/core/node_modules/@types/node/stream.d.ts:112

readableLength​

readonly readableLength: number

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

Since​

v9.4.0

Inherited from​

Readable.readableLength

Source​

packages/core/node_modules/@types/node/stream.d.ts:119

readableObjectMode​

readonly readableObjectMode: boolean

Getter for the property objectMode of a given Readable stream.

Since​

v12.3.0

Inherited from​

Readable.readableObjectMode

Source​

packages/core/node_modules/@types/node/stream.d.ts:124

captureRejectionSymbol​

static readonly captureRejectionSymbol: typeof captureRejectionSymbol

Inherited from​

Readable.captureRejectionSymbol

Source​

packages/core/node_modules/@types/node/events.d.ts:328

captureRejections​

static captureRejections: boolean

Sets or gets the default captureRejection value for all emitters.

Inherited from​

Readable.captureRejections

Source​

packages/core/node_modules/@types/node/events.d.ts:333

defaultMaxListeners​

static defaultMaxListeners: number

Inherited from​

Readable.defaultMaxListeners

Source​

packages/core/node_modules/@types/node/events.d.ts:334

errorMonitor​

static readonly errorMonitor: typeof errorMonitor

This symbol shall be used to install a listener for only monitoring 'error' events. Listeners installed using this symbol are called before the regular 'error' listeners are called.

Installing a listener using this symbol does not change the behavior once an 'error' event is emitted, therefore the process will still crash if no regular 'error' listener is installed.

Inherited from​

Readable.errorMonitor

Source​

packages/core/node_modules/@types/node/events.d.ts:327

Methods​

[asyncIterator]()​

[asyncIterator](): AsyncIterableIterator<any>

Returns​

AsyncIterableIterator<any>

Inherited from​

Readable.[asyncIterator]

Source​

packages/core/node_modules/@types/node/stream.d.ts:503

_construct()?​

optional _construct(callback): void

Parameters​

• callback: (error?) => void

Returns​

void

Inherited from​

Readable._construct

Source​

packages/core/node_modules/@types/node/stream.d.ts:141

_destroy()​

_destroy(error, callback): void

Parameters​

• error: Error

• callback: (error?) => void

Returns​

void

Inherited from​

Readable._destroy

Source​

packages/core/node_modules/@types/node/stream.d.ts:423

_read()​

_read(): void

Returns​

void

Overrides​

Readable._read

Source​

packages/core/src/utils/serializers.ts:39

addListener()​

addListener(event, listener)​

addListener(event, listener): this

Event emitter The defined events on documents including:

  1. close
  2. data
  3. end
  4. error
  5. pause
  6. readable
  7. resume
Parameters​

• event: "close"

• listener: () => void

Returns​

this

Inherited from​

Readable.addListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:447

addListener(event, listener)​

addListener(event, listener): this

Parameters​

• event: "data"

• listener: (chunk) => void

Returns​

this

Inherited from​

Readable.addListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:448

addListener(event, listener)​

addListener(event, listener): this

Parameters​

• event: "end"

• listener: () => void

Returns​

this

Inherited from​

Readable.addListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:449

addListener(event, listener)​

addListener(event, listener): this

Parameters​

• event: "error"

• listener: (err) => void

Returns​

this

Inherited from​

Readable.addListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:450

addListener(event, listener)​

addListener(event, listener): this

Parameters​

• event: "pause"

• listener: () => void

Returns​

this

Inherited from​

Readable.addListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:451

addListener(event, listener)​

addListener(event, listener): this

Parameters​

• event: "readable"

• listener: () => void

Returns​

this

Inherited from​

Readable.addListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:452

addListener(event, listener)​

addListener(event, listener): this

Parameters​

• event: "resume"

• listener: () => void

Returns​

this

Inherited from​

Readable.addListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:453

addListener(event, listener)​

addListener(event, listener): this

Parameters​

• event: string | symbol

• listener: (...args) => void

Returns​

this

Inherited from​

Readable.addListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:454

destroy()​

destroy(error?): this

Destroy the stream. Optionally emit an 'error' event, and emit a 'close'event (unless emitClose is set to false). After this call, the readable stream will release any internal resources and subsequent calls to push()will be ignored.

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 readable._destroy().

Parameters​

• error?: Error

Error which will be passed as payload in 'error' event

Returns​

this

Inherited from​

Readable.destroy

Since​

v8.0.0

Source​

packages/core/node_modules/@types/node/stream.d.ts:435

emit()​

emit(event)​

emit(event): boolean

Parameters​

• event: "close"

Returns​

boolean

Inherited from​

Readable.emit

Source​

packages/core/node_modules/@types/node/stream.d.ts:455

emit(event, chunk)​

emit(event, chunk): boolean

Parameters​

• event: "data"

• chunk: any

Returns​

boolean

Inherited from​

Readable.emit

Source​

packages/core/node_modules/@types/node/stream.d.ts:456

emit(event)​

emit(event): boolean

Parameters​

• event: "end"

Returns​

boolean

Inherited from​

Readable.emit

Source​

packages/core/node_modules/@types/node/stream.d.ts:457

emit(event, err)​

emit(event, err): boolean

Parameters​

• event: "error"

• err: Error

Returns​

boolean

Inherited from​

Readable.emit

Source​

packages/core/node_modules/@types/node/stream.d.ts:458

emit(event)​

emit(event): boolean

Parameters​

• event: "pause"

Returns​

boolean

Inherited from​

Readable.emit

Source​

packages/core/node_modules/@types/node/stream.d.ts:459

emit(event)​

emit(event): boolean

Parameters​

• event: "readable"

Returns​

boolean

Inherited from​

Readable.emit

Source​

packages/core/node_modules/@types/node/stream.d.ts:460

emit(event)​

emit(event): boolean

Parameters​

• event: "resume"

Returns​

boolean

Inherited from​

Readable.emit

Source​

packages/core/node_modules/@types/node/stream.d.ts:461

emit(event, args)​

emit(event, ...args): boolean

Parameters​

• event: string | symbol

• ...args: any[]

Returns​

boolean

Inherited from​

Readable.emit

Source​

packages/core/node_modules/@types/node/stream.d.ts:462

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.

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) ]

Returns​

(string | symbol)[]

Inherited from​

Readable.eventNames

Since​

v6.0.0

Source​

packages/core/node_modules/@types/node/events.d.ts:669

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

Inherited from​

Readable.getMaxListeners

Since​

v1.0.0

Source​

packages/core/node_modules/@types/node/events.d.ts:526

isPaused()​

isPaused(): boolean

The readable.isPaused() method returns the current operating state of theReadable. This is used primarily by the mechanism that underlies thereadable.pipe() method. In most typical cases, there will be no reason to use this method directly.

const readable = new stream.Readable();

readable.isPaused(); // === false
readable.pause();
readable.isPaused(); // === true
readable.resume();
readable.isPaused(); // === false

Returns​

boolean

Inherited from​

Readable.isPaused

Since​

v0.11.14

Source​

packages/core/node_modules/@types/node/stream.d.ts:302

listenerCount()​

listenerCount(eventName): number

Returns the number of listeners listening to the event named eventName.

Parameters​

• eventName: string | symbol

The name of the event being listened for

Returns​

number

Inherited from​

Readable.listenerCount

Since​

v3.2.0

Source​

packages/core/node_modules/@types/node/events.d.ts:616

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​

• eventName: string | symbol

Returns​

Function[]

Inherited from​

Readable.listeners

Since​

v0.1.26

Source​

packages/core/node_modules/@types/node/events.d.ts:539

off()​

off(eventName, listener): this

Alias for emitter.removeListener().

Parameters​

• eventName: string | symbol

• listener: (...args) => void

Returns​

this

Inherited from​

Readable.off

Since​

v10.0.0

Source​

packages/core/node_modules/@types/node/events.d.ts:499

on()​

on(event, listener)​

on(event, listener): this

Parameters​

• event: "close"

• listener: () => void

Returns​

this

Inherited from​

Readable.on

Source​

packages/core/node_modules/@types/node/stream.d.ts:463

on(event, listener)​

on(event, listener): this

Parameters​

• event: "data"

• listener: (chunk) => void

Returns​

this

Inherited from​

Readable.on

Source​

packages/core/node_modules/@types/node/stream.d.ts:464

on(event, listener)​

on(event, listener): this

Parameters​

• event: "end"

• listener: () => void

Returns​

this

Inherited from​

Readable.on

Source​

packages/core/node_modules/@types/node/stream.d.ts:465

on(event, listener)​

on(event, listener): this

Parameters​

• event: "error"

• listener: (err) => void

Returns​

this

Inherited from​

Readable.on

Source​

packages/core/node_modules/@types/node/stream.d.ts:466

on(event, listener)​

on(event, listener): this

Parameters​

• event: "pause"

• listener: () => void

Returns​

this

Inherited from​

Readable.on

Source​

packages/core/node_modules/@types/node/stream.d.ts:467

on(event, listener)​

on(event, listener): this

Parameters​

• event: "readable"

• listener: () => void

Returns​

this

Inherited from​

Readable.on

Source​

packages/core/node_modules/@types/node/stream.d.ts:468

on(event, listener)​

on(event, listener): this

Parameters​

• event: "resume"

• listener: () => void

Returns​

this

Inherited from​

Readable.on

Source​

packages/core/node_modules/@types/node/stream.d.ts:469

on(event, listener)​

on(event, listener): this

Parameters​

• event: string | symbol

• listener: (...args) => void

Returns​

this

Inherited from​

Readable.on

Source​

packages/core/node_modules/@types/node/stream.d.ts:470

once()​

once(event, listener)​

once(event, listener): this

Parameters​

• event: "close"

• listener: () => void

Returns​

this

Inherited from​

Readable.once

Source​

packages/core/node_modules/@types/node/stream.d.ts:471

once(event, listener)​

once(event, listener): this

Parameters​

• event: "data"

• listener: (chunk) => void

Returns​

this

Inherited from​

Readable.once

Source​

packages/core/node_modules/@types/node/stream.d.ts:472

once(event, listener)​

once(event, listener): this

Parameters​

• event: "end"

• listener: () => void

Returns​

this

Inherited from​

Readable.once

Source​

packages/core/node_modules/@types/node/stream.d.ts:473

once(event, listener)​

once(event, listener): this

Parameters​

• event: "error"

• listener: (err) => void

Returns​

this

Inherited from​

Readable.once

Source​

packages/core/node_modules/@types/node/stream.d.ts:474

once(event, listener)​

once(event, listener): this

Parameters​

• event: "pause"

• listener: () => void

Returns​

this

Inherited from​

Readable.once

Source​

packages/core/node_modules/@types/node/stream.d.ts:475

once(event, listener)​

once(event, listener): this

Parameters​

• event: "readable"

• listener: () => void

Returns​

this

Inherited from​

Readable.once

Source​

packages/core/node_modules/@types/node/stream.d.ts:476

once(event, listener)​

once(event, listener): this

Parameters​

• event: "resume"

• listener: () => void

Returns​

this

Inherited from​

Readable.once

Source​

packages/core/node_modules/@types/node/stream.d.ts:477

once(event, listener)​

once(event, listener): this

Parameters​

• event: string | symbol

• listener: (...args) => void

Returns​

this

Inherited from​

Readable.once

Source​

packages/core/node_modules/@types/node/stream.d.ts:478

pause()​

pause(): this

The readable.pause() method will cause a stream in flowing mode to stop emitting 'data' events, switching out of flowing mode. Any data that becomes available will remain in the internal buffer.

const readable = getReadableStreamSomehow();
readable.on('data', (chunk) => {
  console.log(`Received ${chunk.length} bytes of data.`);
  readable.pause();
  console.log('There will be no additional data for 1 second.');
  setTimeout(() => {
    console.log('Now data will start flowing again.');
    readable.resume();
  }, 1000);
});

The readable.pause() method has no effect if there is a 'readable'event listener.

Returns​

this

Inherited from​

Readable.pause

Since​

v0.9.4

Source​

packages/core/node_modules/@types/node/stream.d.ts:266

pipe()​

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

Type parameters​

• T extends WritableStream

Parameters​

• destination: T

• options?: Object

• options.end?: boolean

Returns​

T

Inherited from​

Readable.pipe

Source​

packages/core/node_modules/@types/node/stream.d.ts:26

prependListener()​

prependListener(event, listener)​

prependListener(event, listener): this

Parameters​

• event: "close"

• listener: () => void

Returns​

this

Inherited from​

Readable.prependListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:479

prependListener(event, listener)​

prependListener(event, listener): this

Parameters​

• event: "data"

• listener: (chunk) => void

Returns​

this

Inherited from​

Readable.prependListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:480

prependListener(event, listener)​

prependListener(event, listener): this

Parameters​

• event: "end"

• listener: () => void

Returns​

this

Inherited from​

Readable.prependListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:481

prependListener(event, listener)​

prependListener(event, listener): this

Parameters​

• event: "error"

• listener: (err) => void

Returns​

this

Inherited from​

Readable.prependListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:482

prependListener(event, listener)​

prependListener(event, listener): this

Parameters​

• event: "pause"

• listener: () => void

Returns​

this

Inherited from​

Readable.prependListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:483

prependListener(event, listener)​

prependListener(event, listener): this

Parameters​

• event: "readable"

• listener: () => void

Returns​

this

Inherited from​

Readable.prependListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:484

prependListener(event, listener)​

prependListener(event, listener): this

Parameters​

• event: "resume"

• listener: () => void

Returns​

this

Inherited from​

Readable.prependListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:485

prependListener(event, listener)​

prependListener(event, listener): this

Parameters​

• event: string | symbol

• listener: (...args) => void

Returns​

this

Inherited from​

Readable.prependListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:486

prependOnceListener()​

prependOnceListener(event, listener)​

prependOnceListener(event, listener): this

Parameters​

• event: "close"

• listener: () => void

Returns​

this

Inherited from​

Readable.prependOnceListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:487

prependOnceListener(event, listener)​

prependOnceListener(event, listener): this

Parameters​

• event: "data"

• listener: (chunk) => void

Returns​

this

Inherited from​

Readable.prependOnceListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:488

prependOnceListener(event, listener)​

prependOnceListener(event, listener): this

Parameters​

• event: "end"

• listener: () => void

Returns​

this

Inherited from​

Readable.prependOnceListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:489

prependOnceListener(event, listener)​

prependOnceListener(event, listener): this

Parameters​

• event: "error"

• listener: (err) => void

Returns​

this

Inherited from​

Readable.prependOnceListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:490

prependOnceListener(event, listener)​

prependOnceListener(event, listener): this

Parameters​

• event: "pause"

• listener: () => void

Returns​

this

Inherited from​

Readable.prependOnceListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:491

prependOnceListener(event, listener)​

prependOnceListener(event, listener): this

Parameters​

• event: "readable"

• listener: () => void

Returns​

this

Inherited from​

Readable.prependOnceListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:492

prependOnceListener(event, listener)​

prependOnceListener(event, listener): this

Parameters​

• event: "resume"

• listener: () => void

Returns​

this

Inherited from​

Readable.prependOnceListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:493

prependOnceListener(event, listener)​

prependOnceListener(event, listener): this

Parameters​

• event: string | symbol

• listener: (...args) => void

Returns​

this

Inherited from​

Readable.prependOnceListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:494

push()​

push(chunk, encoding?): boolean

Parameters​

• chunk: any

• encoding?: BufferEncoding

Returns​

boolean

Inherited from​

Readable.push

Source​

packages/core/node_modules/@types/node/stream.d.ts:422

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()).

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​

• eventName: string | symbol

Returns​

Function[]

Inherited from​

Readable.rawListeners

Since​

v9.4.0

Source​

packages/core/node_modules/@types/node/events.d.ts:569

read()​

read(size?): any

The readable.read() method reads data out of the internal buffer and returns it. If no data is available to be read, null is returned. By default, the data is returned as a Buffer object unless an encoding has been specified using the readable.setEncoding() method or the stream is operating in object mode.

The optional size argument specifies a specific number of bytes to read. Ifsize bytes are not available to be read, null will be returned _unless_the stream has ended, in which case all of the data remaining in the internal buffer will be returned.

If the size argument is not specified, all of the data contained in the internal buffer will be returned.

The size argument must be less than or equal to 1 GiB.

The readable.read() method should only be called on Readable streams operating in paused mode. In flowing mode, readable.read() is called automatically until the internal buffer is fully drained.

const readable = getReadableStreamSomehow();

// 'readable' may be triggered multiple times as data is buffered in
readable.on('readable', () => {
  let chunk;
  console.log('Stream is readable (new data received in buffer)');
  // Use a loop to make sure we read all currently available data
  while (null !== (chunk = readable.read())) {
    console.log(`Read ${chunk.length} bytes of data...`);
  }
});

// 'end' will be triggered once when there is no more data available
readable.on('end', () => {
  console.log('Reached end of stream.');
});

Each call to readable.read() returns a chunk of data, or null. The chunks are not concatenated. A while loop is necessary to consume all data currently in the buffer. When reading a large file .read() may return null, having consumed all buffered content so far, but there is still more data to come not yet buffered. In this case a new 'readable' event will be emitted when there is more data in the buffer. Finally the 'end' event will be emitted when there is no more data to come.

Therefore to read a file's whole contents from a readable, it is necessary to collect chunks across multiple 'readable' events:

const chunks = [];

readable.on('readable', () => {
  let chunk;
  while (null !== (chunk = readable.read())) {
    chunks.push(chunk);
  }
});

readable.on('end', () => {
  const content = chunks.join('');
});

A Readable stream in object mode will always return a single item from a call to readable.read(size), regardless of the value of thesize argument.

If the readable.read() method returns a chunk of data, a 'data' event will also be emitted.

Calling read after the 'end' event has been emitted will return null. No runtime error will be raised.

Parameters​

• size?: number

Optional argument to specify how much data to read.

Returns​

any

Inherited from​

Readable.read

Since​

v0.9.4

Source​

packages/core/node_modules/@types/node/stream.d.ts:219

removeAllListeners()​

removeAllListeners(event?): 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.

Parameters​

• event?: string | symbol

Returns​

this

Inherited from​

Readable.removeAllListeners

Since​

v0.1.26

Source​

packages/core/node_modules/@types/node/events.d.ts:510

removeListener()​

removeListener(event, listener)​

removeListener(event, listener): this

Parameters​

• event: "close"

• listener: () => void

Returns​

this

Inherited from​

Readable.removeListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:495

removeListener(event, listener)​

removeListener(event, listener): this

Parameters​

• event: "data"

• listener: (chunk) => void

Returns​

this

Inherited from​

Readable.removeListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:496

removeListener(event, listener)​

removeListener(event, listener): this

Parameters​

• event: "end"

• listener: () => void

Returns​

this

Inherited from​

Readable.removeListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:497

removeListener(event, listener)​

removeListener(event, listener): this

Parameters​

• event: "error"

• listener: (err) => void

Returns​

this

Inherited from​

Readable.removeListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:498

removeListener(event, listener)​

removeListener(event, listener): this

Parameters​

• event: "pause"

• listener: () => void

Returns​

this

Inherited from​

Readable.removeListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:499

removeListener(event, listener)​

removeListener(event, listener): this

Parameters​

• event: "readable"

• listener: () => void

Returns​

this

Inherited from​

Readable.removeListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:500

removeListener(event, listener)​

removeListener(event, listener): this

Parameters​

• event: "resume"

• listener: () => void

Returns​

this

Inherited from​

Readable.removeListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:501

removeListener(event, listener)​

removeListener(event, listener): this

Parameters​

• event: string | symbol

• listener: (...args) => void

Returns​

this

Inherited from​

Readable.removeListener

Source​

packages/core/node_modules/@types/node/stream.d.ts:502

resume()​

resume(): this

The readable.resume() method causes an explicitly paused Readable stream to resume emitting 'data' events, switching the stream into flowing mode.

The readable.resume() method can be used to fully consume the data from a stream without actually processing any of that data:

getReadableStreamSomehow()
  .resume()
  .on('end', () => {
    console.log('Reached the end, but did not read anything.');
  });

The readable.resume() method has no effect if there is a 'readable'event listener.

Returns​

this

Inherited from​

Readable.resume

Since​

v0.9.4

Source​

packages/core/node_modules/@types/node/stream.d.ts:285

setEncoding()​

setEncoding(encoding): this

The readable.setEncoding() method sets the character encoding for data read from the Readable stream.

By default, no encoding is assigned and stream data will be returned asBuffer objects. Setting an encoding causes the stream data to be returned as strings of the specified encoding rather than as Bufferobjects. For instance, calling readable.setEncoding('utf8') will cause the output data to be interpreted as UTF-8 data, and passed as strings. Callingreadable.setEncoding('hex') will cause the data to be encoded in hexadecimal string format.

The Readable stream will properly handle multi-byte characters delivered through the stream that would otherwise become improperly decoded if simply pulled from the stream as Buffer objects.

const readable = getReadableStreamSomehow();
readable.setEncoding('utf8');
readable.on('data', (chunk) => {
  assert.equal(typeof chunk, 'string');
  console.log('Got %d characters of string data:', chunk.length);
});

Parameters​

• encoding: BufferEncoding

The encoding to use.

Returns​

this

Inherited from​

Readable.setEncoding

Since​

v0.9.4

Source​

packages/core/node_modules/@types/node/stream.d.ts:244

setMaxListeners()​

setMaxListeners(n): this

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​

• n: number

Returns​

this

Inherited from​

Readable.setMaxListeners

Since​

v0.3.5

Source​

packages/core/node_modules/@types/node/events.d.ts:520

unpipe()​

unpipe(destination?): this

The readable.unpipe() method detaches a Writable stream previously attached using the pipe method.

If the destination is not specified, then all pipes are detached.

If the destination is specified, but no pipe is set up for it, then the method does nothing.

const fs = require('fs');
const readable = getReadableStreamSomehow();
const writable = fs.createWriteStream('file.txt');
// All the data from readable goes into 'file.txt',
// but only for the first second.
readable.pipe(writable);
setTimeout(() => {
  console.log('Stop writing to file.txt.');
  readable.unpipe(writable);
  console.log('Manually close the file stream.');
  writable.end();
}, 1000);

Parameters​

• destination?: WritableStream

Optional specific stream to unpipe

Returns​

this

Inherited from​

Readable.unpipe

Since​

v0.9.4

Source​

packages/core/node_modules/@types/node/stream.d.ts:329

unshift()​

unshift(chunk, encoding?): void

Passing chunk as null signals the end of the stream (EOF) and behaves the same as readable.push(null), after which no more data can be written. The EOF signal is put at the end of the buffer and any buffered data will still be flushed.

The readable.unshift() method pushes a chunk of data back into the internal buffer. This is useful in certain situations where a stream is being consumed by code that needs to "un-consume" some amount of data that it has optimistically pulled out of the source, so that the data can be passed on to some other party.

The stream.unshift(chunk) method cannot be called after the 'end' event has been emitted or a runtime error will be thrown.

Developers using stream.unshift() often should consider switching to use of a Transform stream instead. See the API for stream implementers section for more information.

// Pull off a header delimited by \n\n.
// Use unshift() if we get too much.
// Call the callback with (error, header, stream).
const { StringDecoder } = require('string_decoder');
function parseHeader(stream, callback) {
  stream.on('error', callback);
  stream.on('readable', onReadable);
  const decoder = new StringDecoder('utf8');
  let header = '';
  function onReadable() {
    let chunk;
    while (null !== (chunk = stream.read())) {
      const str = decoder.write(chunk);
      if (str.includes('\n\n')) {
        // Found the header boundary.
        const split = str.split(/\n\n/);
        header += split.shift();
        const remaining = split.join('\n\n');
        const buf = Buffer.from(remaining, 'utf8');
        stream.removeListener('error', callback);
        // Remove the 'readable' listener before unshifting.
        stream.removeListener('readable', onReadable);
        if (buf.length)
          stream.unshift(buf);
        // Now the body of the message can be read from the stream.
        callback(null, header, stream);
        return;
      }
      // Still reading the header.
      header += str;
    }
  }
}

Unlike push, stream.unshift(chunk) will not end the reading process by resetting the internal reading state of the stream. This can cause unexpected results if readable.unshift() is called during a read (i.e. from within a _read implementation on a custom stream). Following the call to readable.unshift() with an immediate push will reset the reading state appropriately, however it is best to simply avoid calling readable.unshift() while in the process of performing a read.

Parameters​

• chunk: any

Chunk of data to unshift onto the read queue. For streams not operating in object mode, chunk must be a string, Buffer, Uint8Array or null. For object mode streams, chunk may be any JavaScript value.

• encoding?: BufferEncoding

Encoding of string chunks. Must be a valid Buffer encoding, such as 'utf8' or 'ascii'.

Returns​

void

Inherited from​

Readable.unshift

Since​

v0.9.11

Source​

packages/core/node_modules/@types/node/stream.d.ts:395

wrap()​

wrap(stream): this

Prior to Node.js 0.10, streams did not implement the entire stream module API as it is currently defined. (See Compatibility for more information.)

When using an older Node.js library that emits 'data' events and has a pause method that is advisory only, thereadable.wrap() method can be used to create a Readable stream that uses the old stream as its data source.

It will rarely be necessary to use readable.wrap() but the method has been provided as a convenience for interacting with older Node.js applications and libraries.

const { OldReader } = require('./old-api-module.js');
const { Readable } = require('stream');
const oreader = new OldReader();
const myReader = new Readable().wrap(oreader);

myReader.on('readable', () => {
  myReader.read(); // etc.
});

Parameters​

• stream: ReadableStream

An "old style" readable stream

Returns​

this

Inherited from​

Readable.wrap

Since​

v0.9.4

Source​

packages/core/node_modules/@types/node/stream.d.ts:421

from()​

static from(iterable, options?): Readable

A utility method for creating Readable Streams out of iterators.

Parameters​

• iterable: Iterable<any> | AsyncIterable<any>

• options?: ReadableOptions

Returns​

Readable

Inherited from​

Readable.from

Source​

packages/core/node_modules/@types/node/stream.d.ts:56

fromWeb()​

Experimental

static fromWeb(readableStream, options?): Readable

A utility method for creating a Readable from a web ReadableStream.

Parameters​

• readableStream: ReadableStream<any>

• options?: Pick<ReadableOptions, "encoding" | "highWaterMark" | "objectMode" | "signal">

Returns​

Readable

Inherited from​

Readable.fromWeb

Since​

v17.0.0

Source​

packages/core/node_modules/@types/node/stream.d.ts:62

getEventListeners()​

static getEventListeners(emitter, name): Function[]

Returns a copy of the array of listeners for the event named eventName.

For EventEmitters this behaves exactly the same as calling .listeners on the emitter.

For EventTargets this is the only way to get the event listeners for the event target. This is useful for debugging and diagnostic purposes.

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]
}

Parameters​

• emitter: EventEmitter | _DOMEventTarget

• name: string | symbol

Returns​

Function[]

Inherited from​

Readable.getEventListeners

Since​

v15.2.0, v14.17.0

Source​

packages/core/node_modules/@types/node/events.d.ts:299

isDisturbed()​

static isDisturbed(stream): boolean

Returns whether the stream has been read from or cancelled.

Parameters​

• stream: Readable | ReadableStream

Returns​

boolean

Inherited from​

Readable.isDisturbed

Since​

v16.8.0

Source​

packages/core/node_modules/@types/node/stream.d.ts:67

listenerCount()​

static listenerCount(emitter, eventName): number

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

const { EventEmitter, listenerCount } = require('events');
const myEmitter = new EventEmitter();
myEmitter.on('event', () => {});
myEmitter.on('event', () => {});
console.log(listenerCount(myEmitter, 'event'));
// Prints: 2

Parameters​

• emitter: EventEmitter

The emitter to query

• eventName: string | symbol

The event name

Returns​

number

Inherited from​

Readable.listenerCount

Since​

v0.9.12

Deprecated​

Since v3.2.0 - Use listenerCount instead.

Source​

packages/core/node_modules/@types/node/events.d.ts:271

on()​

static on(emitter, eventName, options?): AsyncIterableIterator<any>

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:

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());

Parameters​

• emitter: EventEmitter

• eventName: string

The name of the event being listened for

• options?: StaticEventEmitterOptions

Returns​

AsyncIterableIterator<any>

that iterates eventName events emitted by the emitter

Inherited from​

Readable.on

Since​

v13.6.0, v12.16.0

Source​

packages/core/node_modules/@types/node/events.d.ts:254

once()​

once(emitter, eventName, options)​

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

Creates a Promise that is fulfilled when the EventEmitter emits the given event or that is rejected if the EventEmitter emits 'error' while waiting. The Promise will resolve with an array of all the arguments emitted to the given event.

This method is intentionally generic and works with the web platform EventTarget interface, which has no special'error' event semantics and does not listen to the 'error' event.

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:

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:

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!
Parameters​

• emitter: _NodeEventTarget

• eventName: string | symbol

• options?: StaticEventEmitterOptions

Returns​

Promise<any[]>

Inherited from​

Readable.once

Since​

v11.13.0, v10.16.0

Source​

packages/core/node_modules/@types/node/events.d.ts:194

once(emitter, eventName, options)​

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

Parameters​

• emitter: _DOMEventTarget

• eventName: string

• options?: StaticEventEmitterOptions

Returns​

Promise<any[]>

Inherited from​

Readable.once

Source​

packages/core/node_modules/@types/node/events.d.ts:195

setMaxListeners()​

static setMaxListeners(n?, ...eventTargets?): void

const {
  setMaxListeners,
  EventEmitter
} = require('events');

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

setMaxListeners(5, target, emitter);

Parameters​

• n?: number

A non-negative number. The maximum number of listeners per EventTarget event.

• ...eventTargets?: (EventEmitter | _DOMEventTarget)[]

Returns​

void

Inherited from​

Readable.setMaxListeners

Since​

v15.4.0

Source​

packages/core/node_modules/@types/node/events.d.ts:317

toWeb()​

Experimental

static toWeb(streamReadable): ReadableStream<any>

A utility method for creating a web ReadableStream from a Readable.

Parameters​

• streamReadable: Readable

Returns​

ReadableStream<any>

Inherited from​

Readable.toWeb

Since​

v17.0.0

Source​

packages/core/node_modules/@types/node/stream.d.ts:73