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

OperationContext.errorMonitor

Source

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

Methods

addAsyncRequest()

addAsyncRequest(promise): void

Parameters

• promise: any

Returns

void

Inherited from

OperationContext.addAsyncRequest

Source

packages/core/src/utils/context.ts:167

addListener()

addListener(eventName, listener): this

Alias for emitter.on(eventName, listener).

Parameters

• eventName: string | symbol

• listener: (...args) => void

Returns

this

Inherited from

OperationContext.addListener

Since

v0.1.26

Source

packages/core/node_modules/@types/node/events.d.ts:354

cookie(param, value, options): void

For compatibility reason

Parameters

• param: any

• value: any

• options: any= undefined

Returns

void

Source

packages/core/src/utils/context.ts:648

createStream()

createStream(): void

Create a buffer stream

Returns

void

Inherited from

OperationContext.createStream

Source

packages/core/src/utils/context.ts:296

emit()

emit(eventName, ...args): boolean

Synchronously calls each of the listeners registered for the event namedeventName, in the order they were registered, passing the supplied arguments to each.

Returns true if the event had listeners, false otherwise.

const EventEmitter = require('events');
const myEmitter = new EventEmitter();

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

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

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

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

Parameters

• eventName: string | symbol

• ...args: any[]

Returns

boolean

Inherited from

OperationContext.emit

Since

v0.1.26

Source

packages/core/node_modules/@types/node/events.d.ts:610

emitError()

emitError(err): void

Parameters

• err: any

Returns

void

Source

packages/core/src/utils/context.ts:907

end()

end(): Promise<any>

Flush the request

Returns

Promise<any>

Overrides

OperationContext.end

Emits

'finish' event

Throws

Error if the request was already ended

Source

packages/core/src/utils/context.ts:702

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

OperationContext.eventNames

Since

v6.0.0

Source

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

execute()

execute(): Promise<any>

Execute the target route

Returns

Promise<any>

Source

packages/core/src/utils/context.ts:817

getCurrentUser()

getCurrentUser<K>(refresh): Promise<K>

Get the current user from session

Type parameters

• K extends User

Parameters

• refresh: boolean= false

Returns

Promise<K>

Inherited from

OperationContext.getCurrentUser

Source

packages/core/src/utils/context.ts:361

getCurrentUserId()

getCurrentUserId(): string

Get the current user id from session

Returns

string

Overrides

OperationContext.getCurrentUserId

Source

packages/core/src/utils/context.ts:800

getExecutor()

getExecutor(): Service<any, Events>

Return the service handling the request

Returns

Service<any, Events>

Source

packages/core/src/utils/context.ts:810

getExtension()

getExtension<K>(name): K

Get an extension of the context

Type parameters

• K = any

Parameters

• name: string

of the extension

Returns

K

extension object

Inherited from

OperationContext.getExtension

Source

packages/core/src/utils/context.ts:126

getHttpContext()

getHttpContext(): HttpContext

Get current http context

getInput()

getInput(sanitizedOptions): Promise<T>

Parameters

• sanitizedOptions: IOptions & Object= undefined

Returns

Promise<T>

Inherited from

OperationContext.getInput

Source

packages/core/src/utils/context.ts:198

getLocale()

getLocale(): string

Get the request locale if found

Returns

string

Source

packages/core/src/utils/context.ts:824

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

OperationContext.getMaxListeners

Since

v1.0.0

Source

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

getOutput()

getOutput(): string

Get output as string, if a OutputStream is provided it will returned null

Returns

string

Inherited from

OperationContext.getOutput

Source

packages/core/src/utils/context.ts:175

getOutputStream()

getOutputStream(): Writable

Get the HTTP stream to output raw data

Returns

Writable

Inherited from

OperationContext.getOutputStream

Source

packages/core/src/utils/context.ts:271

getParameters()

getParameters(): any

Returns

any

Source

packages/core/src/utils/context.ts:542

getPathParameters()

getPathParameters(): any

Returns

any

Source

packages/core/src/utils/context.ts:555

getRawInput()

getRawInput(limit, timeout): Promise<Buffer>

Parameters

• limit: number= undefined

• timeout: number= 60000

Returns

Promise<Buffer>

Overrides

OperationContext.getRawInput

Source

packages/core/src/utils/context.ts:516

getRawInputAsString()

getRawInputAsString(limit, timeout, encoding?): Promise<string>

Parameters

• limit: number= undefined

• timeout: number= 60000

• encoding?: string

Returns

Promise<string>

Overrides

OperationContext.getRawInputAsString

Source

packages/core/src/utils/context.ts:505

getRawStream()

getRawStream(): Readable

Returns

Readable

Overrides

OperationContext.getRawStream

Source

packages/core/src/utils/context.ts:523

getRequest()

getRequest(): IncomingMessage

Retrieve a http.IncomingMessage valid from Context

Need more testing

Returns

IncomingMessage

Source

packages/core/src/utils/context.ts:757

getRequestBody()

getRequestBody(sanitizedOptions): Promise<T>

Alias to keep compatibility with WebContext

Parameters

• sanitizedOptions: any= undefined

Returns

Promise<T>

Source

packages/core/src/utils/context.ts:731

getRequestParameters()

getRequestParameters(): any

Returns

any

Source

packages/core/src/utils/context.ts:534

getResponseBody()

getResponseBody(): any

Get request body

Returns

any

Source

packages/core/src/utils/context.ts:744

getResponseCode()

getResponseCode(): number

Returns

number

Source

packages/core/src/utils/context.ts:634

getResponseCookies()

getResponseCookies(): Map<string, Cookie>

Returns

Map<string, Cookie>

Source

packages/core/src/utils/context.ts:656

getResponseHeaders()

getResponseHeaders(): any

Get output headers

Returns

any

Source

packages/core/src/utils/context.ts:530

getResponseSize()

getResponseSize(): number

Return the response size

Returns

number

Source

packages/core/src/utils/context.ts:692

getRoute()

getRoute(): any

Returns

any

Source

packages/core/src/utils/context.ts:843

getService()

getService<K>(name): K

Get a service from webda

Type parameters

• K extends Service<ServiceParameters, Events>

Parameters

• name: any

of the service

Returns

K

See

Webda

Source

packages/core/src/utils/context.ts:785

getServiceParameters()

getServiceParameters(): any

Returns

any

Source

packages/core/src/utils/context.ts:551

getSession()

getSession<K>(): K

Get linked session

Type parameters

• K = Session

Returns

K

Inherited from

OperationContext.getSession

Source

packages/core/src/utils/context.ts:279

getStream()

getStream(): Writable

Get the HTTP stream to output raw data

Returns

Writable

Source

packages/core/src/utils/context.ts:793

getWebda()

getWebda(): Core<CoreEvents>

Return the webda

Returns

Core<CoreEvents>

Inherited from

OperationContext.getWebda

Source

packages/core/src/utils/context.ts:159

hasFlushedHeaders()

hasFlushedHeaders(): boolean

Return true if Headers got flushed already

Returns

boolean

Source

packages/core/src/utils/context.ts:865

init()

init(force): Promise<WebContext<T, U>>

Parameters

• force: boolean= false

Returns

Promise<WebContext<T, U>>

Overrides

OperationContext.init

Source

packages/core/src/utils/context.ts:892

isEnded()

isEnded(): Promise<any>

Returns

Promise<any>

Source

packages/core/src/utils/context.ts:660

isGlobal()

isGlobal(): boolean

Global context is the default Context

Whenever a request is internal to the system or not linked to a user request

Returns

boolean

Inherited from

OperationContext.isGlobal

Source

packages/core/src/utils/context.ts:386

json()

json(obj): this

Express response allow answer to be sent this way

Parameters

• obj: any

Returns

this

Source

packages/core/src/utils/context.ts:683

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

OperationContext.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

OperationContext.listeners

Since

v0.1.26

Source

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

log()

log(level, ...args): void

Proxy for simplification

Parameters

• level: WorkerLogLevel

• ...args: any[]

Returns

void

Inherited from

OperationContext.log

Source

packages/core/src/utils/context.ts:308

newSession()

newSession(): Promise<Session>

Create a new session

Returns

Promise<Session>

Inherited from

OperationContext.newSession

Source

packages/core/src/utils/context.ts:316

off()

off(eventName, listener): this

Alias for emitter.removeListener().

Parameters

• eventName: string | symbol

• listener: (...args) => void

Returns

this

Inherited from

OperationContext.off

Since

v10.0.0

Source

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

on()

on(eventName, listener): this

Adds the listener function to the end of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventNameand listener will result in the listener being added, and called, multiple times.

server.on('connection', (stream) => {
  console.log('someone connected!');
});

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

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

const myEE = new EventEmitter();
myEE.on('foo', () => console.log('a'));
myEE.prependListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
//   b
//   a

Parameters

• eventName: string | symbol

The name of the event.

• listener: (...args) => void

The callback function

Returns

this

Inherited from

OperationContext.on

Since

v0.1.101

Source

packages/core/node_modules/@types/node/events.d.ts:385

once()

once(eventName, listener): this

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

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

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

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

const myEE = new EventEmitter();
myEE.once('foo', () => console.log('a'));
myEE.prependOnceListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
//   b
//   a

Parameters

• eventName: string | symbol

The name of the event.

• listener: (...args) => void

The callback function

Returns

this

Inherited from

OperationContext.once

Since

v0.3.0

Source

packages/core/node_modules/@types/node/events.d.ts:414

parameter()

parameter(name): any

Parameters

• name: string

Returns

any

Source

packages/core/src/utils/context.ts:538

prependListener()

prependListener(eventName, listener): this

Adds the listener function to the beginning of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventNameand listener will result in the listener being added, and called, multiple times.

server.prependListener('connection', (stream) => {
  console.log('someone connected!');
});

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

Parameters

• eventName: string | symbol

The name of the event.

• listener: (...args) => void

The callback function

Returns

this

Inherited from

OperationContext.prependListener

Since

v6.0.0

Source

packages/core/node_modules/@types/node/events.d.ts:634

prependOnceListener()

prependOnceListener(eventName, listener): this

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

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

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

Parameters

• eventName: string | symbol

The name of the event.

• listener: (...args) => void

The callback function

Returns

this

Inherited from

OperationContext.prependOnceListener

Since

v6.0.0

Source

packages/core/node_modules/@types/node/events.d.ts:650

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

OperationContext.rawListeners

Since

v9.4.0

Source

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

redirect()

redirect(url): void

Redirect to another url

Parameters

• url: string

Returns

void

Source

packages/core/src/utils/context.ts:642

reinit()

reinit(): void

Remove sanitized body

Returns

void

Inherited from

OperationContext.reinit

Source

packages/core/src/utils/context.ts:286

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

OperationContext.removeAllListeners

Since

v0.1.26

Source

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

removeListener()

removeListener(eventName, listener): this

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

const callback = (stream) => {
  console.log('someone connected!');
};
server.on('connection', callback);
// ...
server.removeListener('connection', callback);

removeListener() will remove, at most, one instance of a listener from the listener array. If any single listener has been added multiple times to the listener array for the specified eventName, then removeListener() must be called multiple times to remove each instance.

Once an event is emitted, all listeners attached to it at the time of emitting are called in order. This implies that anyremoveListener() or removeAllListeners() calls after emitting and before the last listener finishes execution will not remove them fromemit() in progress. Subsequent events behave as expected.

const myEmitter = new MyEmitter();

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

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

myEmitter.on('event', callbackA);

myEmitter.on('event', callbackB);

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

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

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

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

const ee = new EventEmitter();

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

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

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

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

Parameters

• eventName: string | symbol

• listener: (...args) => void

Returns

this

Inherited from

OperationContext.removeListener

Since

v0.1.26

Source

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

resetResponse()

resetResponse(): void

Remove everything that was about to be sent

Returns

void

Overrides

OperationContext.resetResponse

Source

packages/core/src/utils/context.ts:572

setExecutor()

setExecutor(executor): void

Parameters

• executor: any

{object} Set the current executor for this context

Returns

void

Source

packages/core/src/utils/context.ts:849

setExtension()

setExtension(name, extension): this

Parameters

• name: string

to add

• extension: any

object to store

Returns

this

Inherited from

OperationContext.setExtension

Source

packages/core/src/utils/context.ts:151

setFlushedHeaders()

setFlushedHeaders(status): void

Set flushed header status

Parameters

• status: boolean= true

Returns

void

Source

packages/core/src/utils/context.ts:873

setHeader()

setHeader(header, value): void

Set a header value

Parameters

• header: any

name

• value: any

Returns

void

Overrides

OperationContext.setHeader

Source

packages/core/src/utils/context.ts:600

setHttpContext()

setHttpContext(httpContext): void

Set current http context

Parameters

• httpContext: HttpContext

current http context

Returns

void

Source

packages/core/src/utils/context.ts:497

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

OperationContext.setMaxListeners

Since

v0.3.5

Source

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

setPathParameters()

setPathParameters(params): void

Parameters

• params: any

Returns

void

Source

packages/core/src/utils/context.ts:564

setServiceParameters()

setServiceParameters(params): void

Parameters

• params: any

Returns

void

Source

packages/core/src/utils/context.ts:559

status()

status(code): this

Express response allow statusCode to be defined this way

Parameters

• code: number

to return

Returns

this

Source

packages/core/src/utils/context.ts:674

write()

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

Write data to the client

Parameters

• output: U

If it is an object it will be serializeb with toPublicJSON, if it is a String it will be appended to the result, if it is a buffer it will replace the result

• encoding?: string

• cb?: (error) => void

Returns

boolean

Overrides

OperationContext.write

Source

packages/core/src/utils/context.ts:584

writeHead()

writeHead(statusCode, headers): this

Write the http return code and some headers Those headers are not flushed yet so can still be overwritten

Parameters

• statusCode: number

to return to the client

• headers: OutgoingHttpHeaders= undefined

to add to the response

Returns

this

Overrides

OperationContext.writeHead

Source

packages/core/src/utils/context.ts:618

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

OperationContext.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

OperationContext.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

OperationContext.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

OperationContext.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

OperationContext.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

OperationContext.setMaxListeners

Since

v15.4.0

Source

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

Class: WebContext<T, U>

Extends​

Type parameters​

Properties​

_body​

Inherited from​

Source​

_cookie​

Source​

_ended​

Source​

_executor​

Source​

_outputHeaders​

Source​

_pathParams​

Source​

_promises​

Inherited from​

Source​

_route​

Source​

_sanitized​

Inherited from​

Source​

_serviceParams​

Source​

_stream​

Inherited from​

Source​

_webda​

Inherited from​

Source​

extensions​

Index signature​

Inherited from​

Source​

headers​

Source​

headersFlushed​

Source​

parameters​

Source​

session​

Inherited from​

Source​

statusCode​

Source​

__globalContext​

Inherited from​

Source​

captureRejectionSymbol​

Inherited from​

Source​

captureRejections​

Inherited from​

Source​

defaultMaxListeners​

Inherited from​

Source​

errorMonitor​

Inherited from​

Source​

Methods​

addAsyncRequest()​

Parameters​

Returns​

Inherited from​

Source​

addListener()​

Parameters​

Returns​

Inherited from​

Since​

Source​

cookie()​

Parameters​

Returns​

Source​

createStream()​

Extends

Type parameters

Properties

_body

Inherited from

Source

_cookie

Source

_ended

Source

_executor

Source

_outputHeaders

Source

_pathParams

Source

_promises

Inherited from

Source

_route

Source

_sanitized

Inherited from

Source

_serviceParams

Source

_stream

Inherited from

Source

_webda

Inherited from

Source

extensions

Index signature

Inherited from

Source

headers

Source

headersFlushed

Source

parameters

Source

session

Inherited from

Source

statusCode

Source

__globalContext

Inherited from

Source

captureRejectionSymbol

Inherited from

Source

captureRejections

Inherited from

Source

defaultMaxListeners

Inherited from

Source

errorMonitor

Inherited from

Source

Methods

addAsyncRequest()

Parameters

Returns

Inherited from

Source

addListener()

Parameters

Returns

Inherited from

Since

Source

cookie()

Parameters

Returns

Source

createStream()

Returns