Optionalcb:
(error?:
Error)
=>
void
Callback after Agenda has started and connected to mongo
Readonlyattrs
Readonlydefinitions
Optional ReadonlyforkedOptional ReadonlyforkReadonlyready
StaticcaptureValue: boolean
Change the default captureRejections option on all new
EventEmitter objects.
Static ReadonlycaptureValue: Symbol.for('nodejs.rejection')
See how to write a custom rejection handler.
Staticdefault
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));
});
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'.
Static Readonlyerror
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.
Optional[captureAlias for emitter.on(eventName, listener).
Cancels any jobs matching the passed MongoDB query, and removes them from the database.
Setup definition for job Method is used by consumers of lib to setup their functions BREAKING CHANGE in v4: options moved from 2nd to 3rd parameter!
Optionaloptions:
Partial<Setup definition for job Method is used by consumers of lib to setup their functions BREAKING CHANGE in v4: options moved from 2nd to 3rd parameter!
Optionaloptions:
Partial<
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 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
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) ]
Creates a scheduled job with given interval and name/names of the job to run
Optionaldata:
undefined
Optionaloptions:
{
forkMode?:
boolean;
skipImmediate?:
boolean;
timezone?:
string
}
Creates a scheduled job with given interval and name/names of the job to run
Optionaldata:
undefined
Optionaloptions:
{
forkMode?:
boolean;
skipImmediate?:
boolean;
timezone?:
string
}
Creates a scheduled job with given interval and name/names of the job to run
Optionaloptions:
{
forkMode?:
boolean;
skipImmediate?:
boolean;
timezone?:
string
}
Creates a scheduled job with given interval and name/names of the job to run
Optionaloptions:
{
forkMode?:
boolean;
skipImmediate?:
boolean;
timezone?:
string
}
Returns the current max listener value for the
EventEmitter which is either set by
emitter.setMaxListeners(n) or defaults to
defaultMaxListeners.
Finds all jobs matching 'query'
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:
Function
The event handler 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] ]
Create a job for this exact moment
Create a job for this exact moment
Alias for emitter.removeListener().
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!');
});
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
// a
The callback function
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!');
});
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
// a
The name of the event.
The callback function
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!');
});
Returns a reference to the EventEmitter, so that calls can be
chained.
The name of the event.
The callback function
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.
The name of the event.
The callback 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 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');
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
|
symbol
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);
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:
// 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:
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');
Returns a reference to the EventEmitter, so that calls can be
chained.
Schedule a job or jobs at a specific time
Schedule a job or jobs at a specific time
Schedule a job or jobs at a specific time
Schedule a job or jobs at a specific time
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.
StaticaddExperimental
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]();
}
}
Disposable that removes the abort listener.
Staticget
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] ]
}
StaticgetReturns 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
}
Staticlistener
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: 2
The emitter to query
The event name
Staticon
import { on, EventEmitter } from 'node:events';
import process from 'node:process';
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:
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());
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 on
process.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 emitted
console.log('done'); // prints 'done'
Optionaloptions:
StaticEventEmitterIteratorOptions
An AsyncIterator that iterates eventName events
emitted by the emitter
import { on, EventEmitter } from 'node:events';
import process from 'node:process';
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:
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());
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 on
process.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 emitted
console.log('done'); // prints 'done'
Optionaloptions:
StaticEventEmitterIteratorOptions
An AsyncIterator that iterates eventName events
emitted by the emitter
Staticonce
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);
}
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 boom
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 event
ee.emit('foo'); // Prints: Waiting for the event was canceled!
Optionaloptions:
StaticEventEmitterOptions
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);
}
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 boom
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 event
ee.emit('foo'); // Prints: Waiting for the event was canceled!
Optionaloptions:
StaticEventEmitterOptions
Staticsetimport { setMaxListeners, EventEmitter } from 'node:events';
const target = new EventTarget();
const emitter = new EventEmitter();
setMaxListeners(5, target, emitter);
Optionaln:
number
A 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.
Agenda Config