docs/Script API/classes/Backend_Script_API._internal_.EventEmitter.EventEmitterAsyncResource.html
Integrates EventEmitter with AsyncResource for EventEmitters that require manual async tracking. Specifically, all events emitted by instances of events.EventEmitterAsyncResource will run within its async context.
import { EventEmitterAsyncResource, EventEmitter } from 'node:events';import { notStrictEqual, strictEqual } from 'node:assert';import { executionAsyncId, triggerAsyncId } from 'node:async_hooks';// Async tracking tooling will identify this as 'Q'.const ee1 = new EventEmitterAsyncResource({ name: 'Q' });// 'foo' listeners will run in the EventEmitters async context.ee1.on('foo', () => { strictEqual(executionAsyncId(), ee1.asyncId); strictEqual(triggerAsyncId(), ee1.triggerAsyncId);});const ee2 = new EventEmitter();// 'foo' listeners on ordinary EventEmitters that do not track async// context, however, run in the same async context as the emit().ee2.on('foo', () => { notStrictEqual(executionAsyncId(), ee2.asyncId); notStrictEqual(triggerAsyncId(), ee2.triggerAsyncId);});Promise.resolve().then(() => { ee1.emit('foo'); ee2.emit('foo');});Copy
The EventEmitterAsyncResource class has the same methods and takes the same options as EventEmitter and AsyncResource themselves.
v17.4.0, v16.14.0
asyncIdasyncResourcetriggerAsyncIdcaptureRejectionscaptureRejectionSymboldefaultMaxListenerserrorMonitor
[captureRejectionSymbol]?addListeneremitemitDestroyeventNamesgetMaxListenerslistenerCountlistenersoffononceprependListenerprependOnceListenerrawListenersremoveAllListenersremoveListenersetMaxListenersaddAbortListenergetEventListenersgetMaxListenerslistenerCountononcesetMaxListeners
new EventEmitterAsyncResource(
options?: EventEmitterAsyncResourceOptions,
): EventEmitterAsyncResource
Optionaloptions: EventEmitterAsyncResourceOptionsOnly optional in child class.
ReadonlyasyncIdasyncId: number
The unique asyncId assigned to the resource.
ReadonlyasyncResourceasyncResource: EventEmitterReferencingAsyncResource
The returned AsyncResource object has an additional eventEmitter property that provides a reference to this EventEmitterAsyncResource.
ReadonlytriggerAsyncIdtriggerAsyncId: number
The same triggerAsyncId that is passed to the AsyncResource constructor.
StaticcaptureRejectionscaptureRejections: boolean
Value: boolean
Change the default captureRejections option on all new EventEmitter objects.
v13.4.0, v12.16.0
Static ReadonlycaptureRejectionSymbolcaptureRejectionSymbol: typeof captureRejectionSymbol
Value: Symbol.for('nodejs.rejection')
See how to write a custom rejection handler.
v13.4.0, v12.16.0
StaticdefaultMaxListenersdefaultMaxListeners: number
By default, a maximum of 10 listeners can be registered for any single event. This limit can be changed for individual EventEmitter instances using the emitter.setMaxListeners(n) method. To change the default for allEventEmitter instances, the events.defaultMaxListeners property can be used. If this value is not a positive number, a RangeError is thrown.
Take caution when setting the events.defaultMaxListeners because the change affects all EventEmitter instances, including those created before the change is made. However, calling emitter.setMaxListeners(n) still has precedence over events.defaultMaxListeners.
This is not a hard limit. The EventEmitter instance will allow more listeners to be added but will output a trace warning to stderr indicating that a "possible EventEmitter memory leak" has been detected. For any single EventEmitter, the emitter.getMaxListeners() and emitter.setMaxListeners() methods can be used to temporarily avoid this warning:
import { EventEmitter } from 'node:events';const emitter = new EventEmitter();emitter.setMaxListeners(emitter.getMaxListeners() + 1);emitter.once('event', () => { // do stuff emitter.setMaxListeners(Math.max(emitter.getMaxListeners() - 1, 0));});Copy
The --trace-warnings command-line flag can be used to display the stack trace for such warnings.
The emitted warning can be inspected with process.on('warning') and will have the additional emitter, type, and count properties, referring to the event emitter instance, the event's name and the number of attached listeners, respectively. Its name property is set to 'MaxListenersExceededWarning'.
v0.11.2
Static ReadonlyerrorMonitorerrorMonitor: 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.
v13.6.0, v12.17.0
Optional[captureRejectionSymbol]"[captureRejectionSymbol]"<K>(
error: Error,
event: string | symbol,
...args: AnyRest,
): void
addListener<K>(
eventName: string | symbol,
listener: (...args: any[]) => void,
): this
Alias for emitter.on(eventName, listener).
v0.1.26
emit<K>(eventName: string | symbol, ...args: AnyRest): boolean
Synchronously calls each of the listeners registered for the event named eventName, in the order they were registered, passing the supplied arguments to each.
Returns true if the event had listeners, false otherwise.
import { EventEmitter } from 'node:events';const myEmitter = new EventEmitter();// First listenermyEmitter.on('event', function firstListener() { console.log('Helloooo! first listener');});// Second listenermyEmitter.on('event', function secondListener(arg1, arg2) { console.log(`event with parameters ${arg1}, ${arg2} in second listener`);});// Third listenermyEmitter.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 listenerCopy
v0.1.26
emitDestroy(): void
Call all destroy hooks. This should only ever be called once. An error will be thrown if it is called more than once. This must be manually called. If the resource is left to be collected by the GC then the destroy hooks will never be called.
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.
import { EventEmitter } from 'node:events';const myEE = new EventEmitter();myEE.on('foo', () => {});myEE.on('bar', () => {});const sym = Symbol('symbol');myEE.on(sym, () => {});console.log(myEE.eventNames());// Prints: ['foo', 'bar', Symbol(symbol)]Copy
v6.0.0
getMaxListeners(): number
Returns the current max listener value for the EventEmitter which is either set by emitter.setMaxListeners(n) or defaults to EventEmitter.defaultMaxListeners.
v1.0.0
listenerCount<K>(eventName: string | symbol, listener?: Function): number
Returns the number of listeners listening for the event named eventName. If listener is provided, it will return how many times the listener is found in the list of the listeners of the event.
The name of the event being listened for
Optionallistener: FunctionThe event handler function
v3.2.0
listeners<K>(eventName: string | symbol): 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] ]Copy
v0.1.26
off<K>(eventName: string | symbol, listener: (...args: any[]) => void): this
Alias for emitter.removeListener().
v10.0.0
on<K>(eventName: string | symbol, listener: (...args: any[]) => void): 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 eventName and listener will result in the listener being added, and called, multiple times.
server.on('connection', (stream) => { console.log('someone connected!');});Copy
Returns a reference to the EventEmitter, so that calls can be chained.
By default, event listeners are invoked in the order they are added. The emitter.prependListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.
import { EventEmitter } from 'node:events';const myEE = new EventEmitter();myEE.on('foo', () => console.log('a'));myEE.prependListener('foo', () => console.log('b'));myEE.emit('foo');// Prints:// b// aCopy
The name of the event.
The callback function
v0.1.101
once<K>(eventName: string | symbol, listener: (...args: any[]) => void): this
Adds a one-time listener function for the event named eventName. The next time eventName is triggered, this listener is removed and then invoked.
server.once('connection', (stream) => { console.log('Ah, we have our first user!');});Copy
Returns a reference to the EventEmitter, so that calls can be chained.
By default, event listeners are invoked in the order they are added. The emitter.prependOnceListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.
import { EventEmitter } from 'node:events';const myEE = new EventEmitter();myEE.once('foo', () => console.log('a'));myEE.prependOnceListener('foo', () => console.log('b'));myEE.emit('foo');// Prints:// b// aCopy
The name of the event.
The callback function
v0.3.0
prependListener<K>(
eventName: string | symbol,
listener: (...args: any[]) => void,
): 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 eventName and listener will result in the listener being added, and called, multiple times.
server.prependListener('connection', (stream) => { console.log('someone connected!');});Copy
Returns a reference to the EventEmitter, so that calls can be chained.
The name of the event.
The callback function
v6.0.0
prependOnceListener<K>(
eventName: string | symbol,
listener: (...args: any[]) => void,
): this
Adds a one-time listener function for the event named eventName to the beginning of the listeners array. The next time eventName is triggered, this listener is removed, and then invoked.
server.prependOnceListener('connection', (stream) => { console.log('Ah, we have our first user!');});Copy
Returns a reference to the EventEmitter, so that calls can be chained.
The name of the event.
The callback function
v6.0.0
rawListeners<K>(eventName: string | symbol): Function[]
Returns a copy of the array of listeners for the event named eventName, including any wrappers (such as those created by .once()).
import { EventEmitter } from 'node:events';const emitter = new EventEmitter();emitter.once('log', () => console.log('log once'));// Returns a new Array with a function `onceWrapper` which has a property// `listener` which contains the original listener bound aboveconst listeners = emitter.rawListeners('log');const logFnWrapper = listeners[0];// Logs "log once" to the console and does not unbind the `once` eventlogFnWrapper.listener();// Logs "log once" to the console and removes the listenerlogFnWrapper();emitter.on('log', () => console.log('log persistently'));// Will return a new Array with a single function bound by `.on()` aboveconst newListeners = emitter.rawListeners('log');// Logs "log persistently" twicenewListeners0;emitter.emit('log');Copy
v9.4.0
removeAllListeners(eventName?: string | symbol): 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.
OptionaleventName: string | symbolv0.1.26
removeListener<K>(
eventName: string | symbol,
listener: (...args: any[]) => void,
): this
Removes the specified listener from the listener array for the event named eventName.
const callback = (stream) => { console.log('someone connected!');};server.on('connection', callback);// ...server.removeListener('connection', callback);Copy
removeListener() will remove, at most, one instance of a listener from the listener array. If any single listener has been added multiple times to the listener array for the specified eventName, then removeListener() must be called multiple times to remove each instance.
Once an event is emitted, all listeners attached to it at the time of emitting are called in order. This implies that any removeListener() or removeAllListeners() calls after emitting and before the last listener finishes execution will not remove them fromemit() in progress. Subsequent events behave as expected.
import { EventEmitter } from 'node:events';class MyEmitter extends EventEmitter {}const myEmitter = new MyEmitter();const callbackA = () => { console.log('A'); myEmitter.removeListener('event', callbackB);};const callbackB = () => { console.log('B');};myEmitter.on('event', callbackA);myEmitter.on('event', callbackB);// callbackA removes listener callbackB but it will still be called.// Internal listener array at time of emit [callbackA, callbackB]myEmitter.emit('event');// Prints:// A// B// callbackB is now removed.// Internal listener array [callbackA]myEmitter.emit('event');// Prints:// ACopy
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:
import { EventEmitter } from 'node:events';const ee = new EventEmitter();function pong() { console.log('pong');}ee.on('ping', pong);ee.once('ping', pong);ee.removeListener('ping', pong);ee.emit('ping');ee.emit('ping');Copy
Returns a reference to the EventEmitter, so that calls can be chained.
v0.1.26
setMaxListeners(n: number): 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 to Infinity (or 0) to indicate an unlimited number of listeners.
Returns a reference to the EventEmitter, so that calls can be chained.
v0.3.5
StaticaddAbortListeneraddAbortListener(
signal: AbortSignal,
resource: (event: Event) => void,
): Disposable
Experimental
Listens once to the abort event on the provided signal.
Listening to the abort event on abort signals is unsafe and may lead to resource leaks since another third party with the signal can call e.stopImmediatePropagation(). Unfortunately Node.js cannot change this since it would violate the web standard. Additionally, the original API makes it easy to forget to remove listeners.
This API allows safely using AbortSignals in Node.js APIs by solving these two issues by listening to the event such that stopImmediatePropagation does not prevent the listener from running.
Returns a disposable so that it may be unsubscribed from more easily.
import { addAbortListener } from 'node:events';function example(signal) { let disposable; try { signal.addEventListener('abort', (e) => e.stopImmediatePropagation()); disposable = addAbortListener(signal, (e) => { // Do something when signal is aborted. }); } finally { disposable?.Symbol.dispose; }}Copy
Disposable that removes the abort listener.
v20.5.0
StaticgetEventListenersgetEventListeners(
emitter: EventTarget | EventEmitter<DefaultEventMap>,
name: string | symbol,
): 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.
import { getEventListeners, EventEmitter } from 'node:events';{ const ee = new EventEmitter(); const listener = () => console.log('Events are fun'); ee.on('foo', listener); console.log(getEventListeners(ee, 'foo')); // [[Function: listener] ]}{ const et = new EventTarget(); const listener = () => console.log('Events are fun'); et.addEventListener('foo', listener); console.log(getEventListeners(et, 'foo')); // [[Function: listener] ]}Copy
v15.2.0, v14.17.0
StaticgetMaxListenersgetMaxListeners(emitter: EventTarget | EventEmitter<DefaultEventMap>): number
Returns the currently set max amount of listeners.
For EventEmitters this behaves exactly the same as calling .getMaxListeners on the emitter.
For EventTargets this is the only way to get the max event listeners for the event target. If the number of event handlers on a single EventTarget exceeds the max set, the EventTarget will print a warning.
import { getMaxListeners, setMaxListeners, EventEmitter } from 'node:events';{ const ee = new EventEmitter(); console.log(getMaxListeners(ee)); // 10 setMaxListeners(11, ee); console.log(getMaxListeners(ee)); // 11}{ const et = new EventTarget(); console.log(getMaxListeners(et)); // 10 setMaxListeners(11, et); console.log(getMaxListeners(et)); // 11}Copy
v19.9.0
StaticlistenerCountlistenerCount(emitter: EventEmitter, eventName: string | symbol): number
A class method that returns the number of listeners for the given eventName registered on the given emitter.
import { EventEmitter, listenerCount } from 'node:events';const myEmitter = new EventEmitter();myEmitter.on('event', () => {});myEmitter.on('event', () => {});console.log(listenerCount(myEmitter, 'event'));// Prints: 2Copy
The emitter to query
The event name
v0.9.12
Since v3.2.0 - Use listenerCount instead.
Staticonon(
emitter: EventEmitter,
eventName: string | symbol,
options?: StaticEventEmitterIteratorOptions,
): AsyncIterator<any[]>
import { on, EventEmitter } from 'node:events';import process from 'node:process';const ee = new EventEmitter();// Emit later onprocess.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 hereCopy
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:
import { on, EventEmitter } from 'node:events';import process from 'node:process';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());Copy
Use the close option to specify an array of event names that will end the iteration:
import { on, EventEmitter } from 'node:events';import process from 'node:process';const ee = new EventEmitter();// Emit later onprocess.nextTick(() => { ee.emit('foo', 'bar'); ee.emit('foo', 42); ee.emit('close');});for await (const event of on(ee, 'foo', { close: ['close'] })) { console.log(event); // prints ['bar'] [42]}// the loop will exit after 'close' is emittedconsole.log('done'); // prints 'done'Copy
Optionaloptions: StaticEventEmitterIteratorOptionsAn AsyncIterator that iterates eventName events emitted by the emitter
v13.6.0, v12.16.0
on(
emitter: EventTarget,
eventName: string,
options?: StaticEventEmitterIteratorOptions,
): AsyncIterator<any[]>
import { on, EventEmitter } from 'node:events';import process from 'node:process';const ee = new EventEmitter();// Emit later onprocess.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 hereCopy
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:
import { on, EventEmitter } from 'node:events';import process from 'node:process';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());Copy
Use the close option to specify an array of event names that will end the iteration:
import { on, EventEmitter } from 'node:events';import process from 'node:process';const ee = new EventEmitter();// Emit later onprocess.nextTick(() => { ee.emit('foo', 'bar'); ee.emit('foo', 42); ee.emit('close');});for await (const event of on(ee, 'foo', { close: ['close'] })) { console.log(event); // prints ['bar'] [42]}// the loop will exit after 'close' is emittedconsole.log('done'); // prints 'done'Copy
Optionaloptions: StaticEventEmitterIteratorOptionsAn AsyncIterator that iterates eventName events emitted by the emitter
v13.6.0, v12.16.0
Staticonceonce(
emitter: EventEmitter,
eventName: string | symbol,
options?: StaticEventEmitterOptions,
): 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.
import { once, EventEmitter } from 'node:events';import process from 'node:process';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.error('error happened', err);}Copy
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:
import { EventEmitter, once } from 'node:events';const ee = new EventEmitter();once(ee, 'error') .then(([err]) => console.log('ok', err.message)) .catch((err) => console.error('error', err.message));ee.emit('error', new Error('boom'));// Prints: ok boomCopy
An AbortSignal can be used to cancel waiting for the event:
import { EventEmitter, once } from 'node: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 eventee.emit('foo'); // Prints: Waiting for the event was canceled!Copy
Optionaloptions: StaticEventEmitterOptionsv11.13.0, v10.16.0
once(
emitter: EventTarget,
eventName: string,
options?: StaticEventEmitterOptions,
): 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.
import { once, EventEmitter } from 'node:events';import process from 'node:process';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.error('error happened', err);}Copy
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:
import { EventEmitter, once } from 'node:events';const ee = new EventEmitter();once(ee, 'error') .then(([err]) => console.log('ok', err.message)) .catch((err) => console.error('error', err.message));ee.emit('error', new Error('boom'));// Prints: ok boomCopy
An AbortSignal can be used to cancel waiting for the event:
import { EventEmitter, once } from 'node: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 eventee.emit('foo'); // Prints: Waiting for the event was canceled!Copy
Optionaloptions: StaticEventEmitterOptionsv11.13.0, v10.16.0
StaticsetMaxListenerssetMaxListeners(
n?: number,
...eventTargets: (EventTarget | EventEmitter<DefaultEventMap>)[],
): void
import { setMaxListeners, EventEmitter } from 'node:events';const target = new EventTarget();const emitter = new EventEmitter();setMaxListeners(5, target, emitter);Copy
Optionaln: numberA non-negative number. The maximum number of listeners per EventTarget event.
Zero or more {EventTarget} or {EventEmitter} instances. If none are specified, n is set as the default max for all newly created {EventTarget} and {EventEmitter} objects.
v15.4.0
Member Visibility
ThemeOSLightDark
Constructors constructor Properties asyncIdasyncResourcetriggerAsyncIdcaptureRejectionscaptureRejectionSymboldefaultMaxListenerserrorMonitor Methods [captureRejectionSymbol]addListeneremitemitDestroyeventNamesgetMaxListenerslistenerCountlistenersoffononceprependListenerprependOnceListenerrawListenersremoveAllListenersremoveListenersetMaxListenersaddAbortListenergetEventListenersgetMaxListenerslistenerCountononcesetMaxListeners