NDJSonReader

@webda/core • Readme | API

Class: NDJSonReader

Read a NDJSON stream

Extends

Writable

Constructors

new NDJSonReader(opts)

new NDJSonReader(opts?): NDJSonReader

Parameters

• opts?: WritableOptions

Returns

NDJSonReader

Inherited from

Writable.constructor

Source

packages/core/node_modules/@types/node/stream.d.ts:595

Properties

closed

readonly closed: boolean

Is true after 'close' has been emitted.

Since

v18.0.0

Inherited from

Writable.closed

Source

packages/core/node_modules/@types/node/stream.d.ts:584

current

current: string = ""

Source

packages/core/src/utils/serializers.ts:52

destroyed

destroyed: boolean

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

Since

v8.0.0

Inherited from

Writable.destroyed

Source

packages/core/node_modules/@types/node/stream.d.ts:579

errored

readonly errored: Error

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

Since

v18.0.0

Inherited from

Writable.errored

Source

packages/core/node_modules/@types/node/stream.d.ts:589

writable

readonly writable: boolean

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

Source

packages/core/node_modules/@types/node/stream.d.ts:540

writableCorked

readonly writableCorked: number

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

Source

packages/core/node_modules/@types/node/stream.d.ts:574

writableEnded

readonly writableEnded: boolean

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

Source

packages/core/node_modules/@types/node/stream.d.ts:546

writableFinished

readonly writableFinished: boolean

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

Since

v12.6.0

Inherited from

Writable.writableFinished

Source

packages/core/node_modules/@types/node/stream.d.ts:551

writableHighWaterMark

readonly writableHighWaterMark: number

Return the value of highWaterMark passed when creating this Writable.

Since

v9.3.0

Inherited from

Writable.writableHighWaterMark

Source

packages/core/node_modules/@types/node/stream.d.ts:556

writableLength

readonly writableLength: number

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

Source

packages/core/node_modules/@types/node/stream.d.ts:563

writableNeedDrain

readonly writableNeedDrain: boolean

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

Source

packages/core/node_modules/@types/node/stream.d.ts:594

writableObjectMode

readonly writableObjectMode: boolean

Getter for the property objectMode of a given Writable stream.

Since

v12.3.0

Inherited from

Writable.writableObjectMode

Source

packages/core/node_modules/@types/node/stream.d.ts:568

captureRejectionSymbol

static readonly captureRejectionSymbol: typeof captureRejectionSymbol

Inherited from

Writable.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

Writable.captureRejections

Source

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

defaultMaxListeners

static defaultMaxListeners: number

Inherited from

Writable.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

Writable.errorMonitor

Source

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

Methods

_construct()?

optional _construct(callback): void

Parameters

• callback: (error?) => void

Returns

void

Inherited from

Writable._construct

Source

packages/core/node_modules/@types/node/stream.d.ts:604

_destroy()

_destroy(error, callback): void

Parameters

• error: Error

• callback: (error?) => void

Returns

void

Inherited from

Writable._destroy

Source

packages/core/node_modules/@types/node/stream.d.ts:605

_final()

_final(callback): void

Parameters

• callback: (error?) => void

Returns

void

Inherited from

Writable._final

Source

packages/core/node_modules/@types/node/stream.d.ts:606

_write()

_write(chunk, encoding, callback): void

Parameters

• chunk: any

• encoding: BufferEncoding

• callback: (error?) => void

Returns

void

Overrides

Writable._write

Source

packages/core/src/utils/serializers.ts:53

_writev()?

optional _writev(chunks, callback): void

Parameters

• chunks: Object[]

• callback: (error?) => void

Returns

void

Inherited from

Writable._writev

Source

packages/core/node_modules/@types/node/stream.d.ts:597

addListener()

addListener(event, listener)

addListener(event, listener): this

Event emitter The defined events on documents including:

close
drain
error
finish
pipe
unpipe

Parameters

• event: "close"

• listener: () => void

Returns

this

Inherited from

Writable.addListener

Source

packages/core/node_modules/@types/node/stream.d.ts:772

addListener(event, listener)

addListener(event, listener): this

Parameters

• event: "drain"

• listener: () => void

Returns

this

Inherited from

Writable.addListener

Source

packages/core/node_modules/@types/node/stream.d.ts:773

addListener(event, listener)

addListener(event, listener): this

Parameters

• event: "error"

• listener: (err) => void

Returns

this

Inherited from

Writable.addListener

Source

packages/core/node_modules/@types/node/stream.d.ts:774

addListener(event, listener)

addListener(event, listener): this

Parameters

• event: "finish"

• listener: () => void

Returns

this

Inherited from

Writable.addListener

Source

packages/core/node_modules/@types/node/stream.d.ts:775

addListener(event, listener)

addListener(event, listener): this

Parameters

• event: "pipe"

• listener: (src) => void

Returns

this

Inherited from

Writable.addListener

Source

packages/core/node_modules/@types/node/stream.d.ts:776

addListener(event, listener)

addListener(event, listener): this

Parameters

• event: "unpipe"

• listener: (src) => void

Returns

this

Inherited from

Writable.addListener

Source

packages/core/node_modules/@types/node/stream.d.ts:777

addListener(event, listener)

addListener(event, listener): this

Parameters

• event: string | symbol

• listener: (...args) => void

Returns

this

Inherited from

Writable.addListener

Source

packages/core/node_modules/@types/node/stream.d.ts:778

cork()

cork(): void

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 implementingwritable._writev() may have an adverse effect on throughput.

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

Returns

void

Inherited from

Writable.cork

Since

v0.11.2

Source

packages/core/node_modules/@types/node/stream.d.ts:710

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 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 towrite() 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

Inherited from

Writable.destroy

Since

v8.0.0

Source

packages/core/node_modules/@types/node/stream.d.ts:761

emit()

emit(event)

emit(event): boolean

Parameters

• event: "close"

Returns

boolean

Inherited from

Writable.emit

Source

packages/core/node_modules/@types/node/stream.d.ts:779

emit(event)

emit(event): boolean

Parameters

• event: "drain"

Returns

boolean

Inherited from

Writable.emit

Source

packages/core/node_modules/@types/node/stream.d.ts:780

emit(event, err)

emit(event, err): boolean

Parameters

• event: "error"

• err: Error

Returns

boolean

Inherited from

Writable.emit

Source

packages/core/node_modules/@types/node/stream.d.ts:781

emit(event)

emit(event): boolean

Parameters

• event: "finish"

Returns

boolean

Inherited from

Writable.emit

Source

packages/core/node_modules/@types/node/stream.d.ts:782

emit(event, src)

emit(event, src): boolean

Parameters

• event: "pipe"

• src: Readable

Returns

boolean

Inherited from

Writable.emit

Source

packages/core/node_modules/@types/node/stream.d.ts:783

emit(event, src)

emit(event, src): boolean

Parameters

• event: "unpipe"

• src: Readable

Returns

boolean

Inherited from

Writable.emit

Source

packages/core/node_modules/@types/node/stream.d.ts:784

emit(event, args)

emit(event, ...args): boolean

Parameters

• event: string | symbol

• ...args: any[]

Returns

boolean

Inherited from

Writable.emit

Source

packages/core/node_modules/@types/node/stream.d.ts:785

end()

end(cb)

end(cb?): this

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!'.
const fs = require('fs');
const file = fs.createWriteStream('example.txt');
file.write('hello, ');
file.end('world!');
// Writing more now is not allowed!

Parameters

• cb?: () => void

Returns

this

Inherited from

Writable.end

Since

v0.9.4

Source

packages/core/node_modules/@types/node/stream.d.ts:693

end(chunk, cb)

end(chunk, cb?): this

Parameters

• chunk: any

• cb?: () => void

Returns

this

Inherited from

Writable.end

Source

packages/core/node_modules/@types/node/stream.d.ts:694

end(chunk, encoding, cb)

end(chunk, encoding, cb?): this

Parameters

• chunk: any

• encoding: BufferEncoding

• cb?: () => void

Returns

this

Inherited from

Writable.end

Source

packages/core/node_modules/@types/node/stream.d.ts:695

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

Writable.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

Writable.getMaxListeners

Since

v1.0.0

Source

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

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

Writable.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

Writable.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

Writable.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

Writable.on

Source

packages/core/node_modules/@types/node/stream.d.ts:786

on(event, listener)

on(event, listener): this

Parameters

• event: "drain"

• listener: () => void

Returns

this

Inherited from

Writable.on

Source

packages/core/node_modules/@types/node/stream.d.ts:787

on(event, listener)

on(event, listener): this

Parameters

• event: "error"

• listener: (err) => void

Returns

this

Inherited from

Writable.on

Source

packages/core/node_modules/@types/node/stream.d.ts:788

on(event, listener)

on(event, listener): this

Parameters

• event: "finish"

• listener: () => void

Returns

this

Inherited from

Writable.on

Source

packages/core/node_modules/@types/node/stream.d.ts:789

on(event, listener)

on(event, listener): this

Parameters

• event: "pipe"

• listener: (src) => void

Returns

this

Inherited from

Writable.on

Source

packages/core/node_modules/@types/node/stream.d.ts:790

on(event, listener)

on(event, listener): this

Parameters

• event: "unpipe"

• listener: (src) => void

Returns

this

Inherited from

Writable.on

Source

packages/core/node_modules/@types/node/stream.d.ts:791

on(event, listener)

on(event, listener): this

Parameters

• event: string | symbol

• listener: (...args) => void

Returns

this

Inherited from

Writable.on

Source

packages/core/node_modules/@types/node/stream.d.ts:792

once()

once(event, listener)

once(event, listener): this

Parameters

• event: "close"

• listener: () => void

Returns

this

Inherited from

Writable.once

Source

packages/core/node_modules/@types/node/stream.d.ts:793

once(event, listener)

once(event, listener): this

Parameters

• event: "drain"

• listener: () => void

Returns

this

Inherited from

Writable.once

Source

packages/core/node_modules/@types/node/stream.d.ts:794

once(event, listener)

once(event, listener): this

Parameters

• event: "error"

• listener: (err) => void

Returns

this

Inherited from

Writable.once

Source

packages/core/node_modules/@types/node/stream.d.ts:795

once(event, listener)

once(event, listener): this

Parameters

• event: "finish"

• listener: () => void

Returns

this

Inherited from

Writable.once

Source

packages/core/node_modules/@types/node/stream.d.ts:796

once(event, listener)

once(event, listener): this

Parameters

• event: "pipe"

• listener: (src) => void

Returns

this

Inherited from

Writable.once

Source

packages/core/node_modules/@types/node/stream.d.ts:797

once(event, listener)

once(event, listener): this

Parameters

• event: "unpipe"

• listener: (src) => void

Returns

this

Inherited from

Writable.once

Source

packages/core/node_modules/@types/node/stream.d.ts:798

once(event, listener)

once(event, listener): this

Parameters

• event: string | symbol

• listener: (...args) => void

Returns

this

Inherited from

Writable.once

Source

packages/core/node_modules/@types/node/stream.d.ts:799

pipe()

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

Type parameters

• T extends WritableStream

Parameters

• destination: T

• options?: Object

• options.end?: boolean

Returns

T

Inherited from

Writable.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

Writable.prependListener

Source

packages/core/node_modules/@types/node/stream.d.ts:800

prependListener(event, listener)

prependListener(event, listener): this

Parameters

• event: "drain"

• listener: () => void

Returns

this

Inherited from

Writable.prependListener

Source

packages/core/node_modules/@types/node/stream.d.ts:801

prependListener(event, listener)

prependListener(event, listener): this

Parameters

• event: "error"

• listener: (err) => void

Returns

this

Inherited from

Writable.prependListener

Source

packages/core/node_modules/@types/node/stream.d.ts:802

prependListener(event, listener)

prependListener(event, listener): this

Parameters

• event: "finish"

• listener: () => void

Returns

this

Inherited from

Writable.prependListener

Source

packages/core/node_modules/@types/node/stream.d.ts:803

prependListener(event, listener)

prependListener(event, listener): this

Parameters

• event: "pipe"

• listener: (src) => void

Returns

this

Inherited from

Writable.prependListener

Source

packages/core/node_modules/@types/node/stream.d.ts:804

prependListener(event, listener)

prependListener(event, listener): this

Parameters

• event: "unpipe"

• listener: (src) => void

Returns

this

Inherited from

Writable.prependListener

Source

packages/core/node_modules/@types/node/stream.d.ts:805

prependListener(event, listener)

prependListener(event, listener): this

Parameters

• event: string | symbol

• listener: (...args) => void

Returns

this

Inherited from

Writable.prependListener

Source

packages/core/node_modules/@types/node/stream.d.ts:806

prependOnceListener()

prependOnceListener(event, listener)

prependOnceListener(event, listener): this

Parameters

• event: "close"

• listener: () => void

Returns

this

Inherited from

Writable.prependOnceListener

Source

packages/core/node_modules/@types/node/stream.d.ts:807

prependOnceListener(event, listener)

prependOnceListener(event, listener): this

Parameters

• event: "drain"

• listener: () => void

Returns

this

Inherited from

Writable.prependOnceListener

Source

packages/core/node_modules/@types/node/stream.d.ts:808

prependOnceListener(event, listener)

prependOnceListener(event, listener): this

Parameters

• event: "error"

• listener: (err) => void

Returns

this

Inherited from

Writable.prependOnceListener

Source

packages/core/node_modules/@types/node/stream.d.ts:809

prependOnceListener(event, listener)

prependOnceListener(event, listener): this

Parameters

• event: "finish"

• listener: () => void

Returns

this

Inherited from

Writable.prependOnceListener

Source

packages/core/node_modules/@types/node/stream.d.ts:810

prependOnceListener(event, listener)

prependOnceListener(event, listener): this

Parameters

• event: "pipe"

• listener: (src) => void

Returns

this

Inherited from

Writable.prependOnceListener

Source

packages/core/node_modules/@types/node/stream.d.ts:811

prependOnceListener(event, listener)

prependOnceListener(event, listener): this

Parameters

• event: "unpipe"

• listener: (src) => void

Returns

this

Inherited from

Writable.prependOnceListener

Source

packages/core/node_modules/@types/node/stream.d.ts:812

prependOnceListener(event, listener)

prependOnceListener(event, listener): this

Parameters

• event: string | symbol

• listener: (...args) => void

Returns

this

Inherited from

Writable.prependOnceListener

Source

packages/core/node_modules/@types/node/stream.d.ts:813

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

Writable.rawListeners

Since

v9.4.0

Source

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

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

Writable.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

Writable.removeListener

Source

packages/core/node_modules/@types/node/stream.d.ts:814

removeListener(event, listener)

removeListener(event, listener): this

Parameters

• event: "drain"

• listener: () => void

Returns

this

Inherited from

Writable.removeListener

Source

packages/core/node_modules/@types/node/stream.d.ts:815

removeListener(event, listener)

removeListener(event, listener): this

Parameters

• event: "error"

• listener: (err) => void

Returns

this

Inherited from

Writable.removeListener

Source

packages/core/node_modules/@types/node/stream.d.ts:816

removeListener(event, listener)

removeListener(event, listener): this

Parameters

• event: "finish"

• listener: () => void

Returns

this

Inherited from

Writable.removeListener

Source

packages/core/node_modules/@types/node/stream.d.ts:817

removeListener(event, listener)

removeListener(event, listener): this

Parameters

• event: "pipe"

• listener: (src) => void

Returns

this

Inherited from

Writable.removeListener

Source

packages/core/node_modules/@types/node/stream.d.ts:818

removeListener(event, listener)

removeListener(event, listener): this

Parameters

• event: "unpipe"

• listener: (src) => void

Returns

this

Inherited from

Writable.removeListener

Source

packages/core/node_modules/@types/node/stream.d.ts:819

removeListener(event, listener)

removeListener(event, listener): this

Parameters

• event: string | symbol

• listener: (...args) => void

Returns

this

Inherited from

Writable.removeListener

Source

packages/core/node_modules/@types/node/stream.d.ts:820

setDefaultEncoding()

setDefaultEncoding(encoding): this

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

Parameters

• encoding: BufferEncoding

The new default encoding

Returns

this

Inherited from

Writable.setDefaultEncoding

Since

v0.11.15

Source

packages/core/node_modules/@types/node/stream.d.ts:670

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

Writable.setMaxListeners

Since

v0.3.5

Source

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

uncork()

uncork(): void

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() usingprocess.nextTick(). Doing so allows batching of allwritable.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();
});

Returns

void

Inherited from

Writable.uncork

Since

v0.11.2

Source

packages/core/node_modules/@types/node/stream.d.ts:744

write()

write(chunk, callback)

write(chunk, callback?): boolean

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 thehighWaterMark 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 or Uint8Array. 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.

Inherited from

Writable.write

Since

v0.9.4

Source

packages/core/node_modules/@types/node/stream.d.ts:663

write(chunk, encoding, callback)

write(chunk, encoding, callback?): boolean

Parameters

• chunk: any

• encoding: BufferEncoding

• callback?: (error) => void

Returns

boolean

Inherited from

Writable.write

Source

packages/core/node_modules/@types/node/stream.d.ts:664

fromWeb()

Experimental

static fromWeb(writableStream, options?): Writable

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

Parameters

• writableStream: WritableStream<any>

• options?: Pick<WritableOptions, "highWaterMark" | "objectMode" | "signal" | "decodeStrings">

Returns

Writable

Inherited from

Writable.fromWeb

Since

v17.0.0

Source

packages/core/node_modules/@types/node/stream.d.ts:528

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

Writable.getEventListeners

Since

v15.2.0, v14.17.0

Source

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

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

Writable.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, any, 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, any, any>

that iterates eventName events emitted by the emitter

Inherited from

Writable.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

Writable.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

Writable.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

Writable.setMaxListeners

Since

v15.4.0

Source

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

toWeb()

Experimental

static toWeb(streamWritable): WritableStream<any>

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

Parameters

• streamWritable: Writable

Returns

WritableStream<any>

Inherited from

Writable.toWeb

Since

v17.0.0

Source

packages/core/node_modules/@types/node/stream.d.ts:534

Class: NDJSonReader

Extends​

Constructors​

new NDJSonReader(opts)​

Parameters​

Returns​

Inherited from​

Source​

Properties​

closed​

Since​

Inherited from​

Source​

current​

Source​

destroyed​

Since​

Inherited from​

Source​

errored​

Since​

Inherited from​

Source​

writable​

Since​

Inherited from​

Source​

writableCorked​

Since​

Inherited from​

Source​

writableEnded​

Since​

Inherited from​

Source​

writableFinished​

Since​

Inherited from​

Source​

writableHighWaterMark​

Since​

Inherited from​

Source​

writableLength​

Since​

Inherited from​

Source​

writableNeedDrain​

Since​

Inherited from​

Source​

writableObjectMode​

Since​

Inherited from​

Source​

captureRejectionSymbol​

Inherited from​

Source​

captureRejections​

Inherited from​

Source​

defaultMaxListeners​

Inherited from​

Source​

errorMonitor​

Inherited from​

Source​

Methods​

_construct()?​

Parameters​

Returns​

Inherited from​

Source​

_destroy()​

Parameters​

Returns​

Inherited from​

Source​

_final()​

Parameters​

Extends

Constructors

new NDJSonReader(opts)

Parameters

Returns

Inherited from

Source

Properties

closed

Since

Inherited from

Source

current

Source

destroyed

Since

Inherited from

Source

errored

Since

Inherited from

Source

writable

Since

Inherited from

Source

writableCorked

Since

Inherited from

Source

writableEnded

Since

Inherited from

Source

writableFinished

Since

Inherited from

Source

writableHighWaterMark

Since

Inherited from

Source

writableLength

Since

Inherited from

Source

writableNeedDrain

Since

Inherited from

Source

writableObjectMode

Since

Inherited from

Source

captureRejectionSymbol

Inherited from

Source

captureRejections

Inherited from

Source

defaultMaxListeners

Inherited from

Source

errorMonitor

Inherited from

Source

Methods

_construct()?

Parameters

Returns

Inherited from

Source

_destroy()

Parameters

Returns

Inherited from

Source

_final()

Parameters

Returns