Class: Collector

connect.Collector

Abstract class for defining a new Collector.

Abstract

Hierarchy

• EventEmitter

  ↳ Collector

  ↳↳ MessageCollector

Constructors

constructor

• new Collector(filter, options?)

Parameters

Name	Type
filter	CollectorFilter<any>
options?	CollectorOptions

Overrides

EventEmitter.constructor

Properties

_idletimeout

• Protected _idletimeout: Timeout

---

_timeout

• Protected _timeout: Timeout

---

collected

• collected: Collection<string, any>

---

ended

• ended: boolean

---

filter

• filter: (...args: any[]) => boolean | Promise<boolean>

Type declaration

▸ (...args): boolean | Promise<boolean>

Parameters

Name	Type
...args	any[]

Returns

boolean | Promise<boolean>

---

options

• options: CollectorOptions

---

captureRejectionSymbol

▪ Static Readonly captureRejectionSymbol: typeof captureRejectionSymbol

Inherited from

EventEmitter.captureRejectionSymbol

---

captureRejections

▪ Static captureRejections: boolean

Sets or gets the default captureRejection value for all emitters.

Inherited from

EventEmitter.captureRejections

---

defaultMaxListeners

▪ Static defaultMaxListeners: number

Inherited from

EventEmitter.defaultMaxListeners

---

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

EventEmitter.errorMonitor

Accessors

next

• get next(): Promise<any>

Returns a promise that resolves with the next collected element; rejects with collected elements if the collector finishes without receiving a next element

Returns

Promise<any>

Methods

[asyncIterator]

▸ [asyncIterator](): any

Allows collectors to be consumed with for-await-of loops

See

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for-await...of

Returns

any

---

addListener

▸ addListener(eventName, listener): Collector

Alias for emitter.on(eventName, listener).

Since

v0.1.26

Parameters

Name	Type
eventName	string | symbol
listener	(...args: any[]) => void

Returns

Collector

Inherited from

EventEmitter.addListener

---

checkEnd

▸ checkEnd(): void

Checks whether the collector should end, and if so, ends it.

Returns

void

---

clearImmediate

▸ clearImmediate(immediate): void

Clears an immediate.

Parameters

Name	Type	Description
immediate	Immediate	Immediate to cancel

Returns

void

---

clearInterval

▸ clearInterval(interval): void

Clears an interval.

Parameters

Name	Type	Description
interval	Timeout	Interval to cancel

Returns

void

---

clearTimeout

▸ clearTimeout(timeout): void

Clears a timeout.

Parameters

Name	Type	Description
timeout	Timeout	Timeout to cancel

Returns

void

---

collect

▸ collect(...args): string | false

Handles incoming events from the handleCollect function. Returns null if the event should not be collected, or returns an object describing the data that should be stored.

See

Collector#handleCollect

Abstract

Parameters

Name	Type
...args	any[]

Returns

string | false

the id if the object should be collected, if it shouldnt be collected then it will return null or false.

---

destroy

▸ destroy(): void

Destroys all assets used by the base client.

Returns

void

---

dispose

▸ dispose(...args): string

Handles incoming events from the handleDispose. Returns null if the event should not be disposed, or returns the key that should be removed.

See

Collector#handleDispose

Abstract

Parameters

Name	Type	Description
...args	any[]	Any args the event listener emits

Returns

string

Key to remove from the collection, if any

---

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

Since

v0.1.26

Parameters

Name	Type
eventName	string | symbol
...args	any[]

Returns

boolean

Inherited from

EventEmitter.emit

---

endReason

▸ endReason(...args): string

The reason this collector has ended or will end with.

Abstract

Parameters

Name	Type
...args	any[]

Returns

string

Reason to end the collector, if any

---

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) ]

Since

v6.0.0

Returns

(string | symbol)[]

Inherited from

EventEmitter.eventNames

---

getMaxListeners

▸ getMaxListeners(): number

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

Since

v1.0.0

Returns

number

Inherited from

EventEmitter.getMaxListeners

---

handleCollect

▸ handleCollect(...args): Promise<void>

Call this to handle an event as a collectable element. Accepts any event data as parameters.

Emits

Collector#collect

Parameters

Name	Type	Description
...args	any[]	The arguments emitted by the listener

Returns

Promise<void>

---

handleDispose

▸ handleDispose(...args): Promise<void>

Call this to remove an element from the collection. Accepts any event data as parameters.

Emits

Collector#dispose

Parameters

Name	Type	Description
...args	any[]	The arguments emitted by the listener

Returns

Promise<void>

---

listenerCount

▸ listenerCount(eventName): number

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

Since

v3.2.0

Parameters

Name	Type	Description
eventName	string | symbol	The name of the event being listened for

Returns

number

Inherited from

EventEmitter.listenerCount

---

listeners

▸ listeners(eventName): Function[]

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

server.on('connection', (stream) => {
  console.log('someone connected!');
});
console.log(util.inspect(server.listeners('connection')));
// Prints: [ [Function] ]

Since

v0.1.26

Parameters

Name	Type
eventName	string | symbol

Returns

Function[]

Inherited from

EventEmitter.listeners

---

off

▸ off(eventName, listener): Collector

Alias for emitter.removeListener().

Since

v10.0.0

Parameters

Name	Type
eventName	string | symbol
listener	(...args: any[]) => void

Returns

Collector

Inherited from

EventEmitter.off

---

on

▸ on(eventName, listener): Collector

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

Since

v0.1.101

Parameters

Name	Type	Description
eventName	string | symbol	The name of the event.
listener	(...args: any[]) => void	The callback function

Returns

Collector

Inherited from

EventEmitter.on

---

once

▸ once(eventName, listener): Collector

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

Since

v0.3.0

Parameters

Name	Type	Description
eventName	string | symbol	The name of the event.
listener	(...args: any[]) => void	The callback function

Returns

Collector

Inherited from

EventEmitter.once

---

prependListener

▸ prependListener(eventName, listener): Collector

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.

Since

v6.0.0

Parameters

Name	Type	Description
eventName	string | symbol	The name of the event.
listener	(...args: any[]) => void	The callback function

Returns

Collector

Inherited from

EventEmitter.prependListener

---

prependOnceListener

▸ prependOnceListener(eventName, listener): Collector

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.

Since

v6.0.0

Parameters

Name	Type	Description
eventName	string | symbol	The name of the event.
listener	(...args: any[]) => void	The callback function

Returns

Collector

Inherited from

EventEmitter.prependOnceListener

---

rawListeners

▸ rawListeners(eventName): Function[]

Returns a copy of the array of listeners for the event named eventName, including any wrappers (such as those created by .once()).

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');

Since

v9.4.0

Parameters

Name	Type
eventName	string | symbol

Returns

Function[]

Inherited from

EventEmitter.rawListeners

---

removeAllListeners

▸ removeAllListeners(event?): Collector

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.

Since

v0.1.26

Parameters

Name	Type
event?	string | symbol

Returns

Collector

Inherited from

EventEmitter.removeAllListeners

---

removeListener

▸ removeListener(eventName, listener): Collector

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.

Since

v0.1.26

Parameters

Name	Type
eventName	string | symbol
listener	(...args: any[]) => void

Returns

Collector

Inherited from

EventEmitter.removeListener

---

resetTimer

▸ resetTimer(options?): void

Resets the collectors timeout and idle timer.

Parameters

Name	Type	Description
options?	Object	Options
options.idle	any	How long to stop the collector after inactivity in milliseconds
options.time	any	How long to run the collector for in milliseconds

Returns

void

---

setImmediate

▸ setImmediate(fn, ...args): Immediate

Sets an immediate that will be automatically cancelled if the client is destroyed.

Parameters

Name	Type	Description
fn	(...args: any[]) => any	Function to execute
...args	any[]	Arguments for the function

Returns

Immediate

---

setInterval

▸ setInterval(fn, delay, ...args): Timeout

Sets an interval that will be automatically cancelled if the client is destroyed.

Parameters

Name	Type	Description
fn	(...args: any[]) => any	Function to execute
delay	number	Time to wait between executions (in milliseconds)
...args	any[]	Arguments for the function

Returns

Timeout

---

setMaxListeners

▸ setMaxListeners(n): Collector

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.

Since

v0.3.5

Parameters

Name	Type
n	number

Returns

Collector

Inherited from

EventEmitter.setMaxListeners

---

setTimeout

▸ setTimeout(fn, delay, ...args): Timeout

Sets a timeout that will be automatically cancelled if the client is destroyed.

Parameters

Name	Type	Description
fn	(...args: any[]) => any	Function to execute
delay	number	Time to wait before executing (in milliseconds)
...args	any[]	Arguments for the function

Returns

Timeout

---

stop

▸ stop(reason?): void

Stops this collector and emits the end event.

Emits

Collector#end

Parameters

Name	Type	Description
reason?	string	The reason this collector is ending

Returns

void

---

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]
}

Since

v15.2.0, v14.17.0

Parameters

Name	Type
emitter	EventEmitter | DOMEventTarget
name	string | symbol

Returns

Function[]

Inherited from

EventEmitter.getEventListeners

---

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

Since

v0.9.12

Deprecated

Since v3.2.0 - Use listenerCount instead.

Parameters

Name	Type	Description
emitter	EventEmitter	The emitter to query
eventName	string | symbol	The event name

Returns

number

Inherited from

EventEmitter.listenerCount

---

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());

Since

v13.6.0, v12.16.0

Parameters

Name	Type	Description
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

EventEmitter.on

---

once

▸ 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!

Since

v11.13.0, v10.16.0

Parameters

Name	Type
emitter	NodeEventTarget
eventName	string | symbol
options?	StaticEventEmitterOptions

Returns

Promise<any[]>

Inherited from

EventEmitter.once

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

Parameters

Name	Type
emitter	DOMEventTarget
eventName	string
options?	StaticEventEmitterOptions

Returns

Promise<any[]>

Inherited from

EventEmitter.once

---

setMaxListeners

▸ Static setMaxListeners(n?, ...eventTargets): void

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

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

setMaxListeners(5, target, emitter);

Since

v15.4.0

Parameters

Name	Type	Description
n?	number	A non-negative number. The maximum number of listeners per EventTarget event.
...eventTargets	(EventEmitter | DOMEventTarget)[]	-

Returns

void

Inherited from

EventEmitter.setMaxListeners