ProtectedchunksStores current response payload.
This will not store anything in case NoDataStorage flag is enabled
ProtectedchunksCurrent response length.
Will always be zero in case NoDataStorage flag is enabled
ProtectedfeaturesProtectedhandleInternal Easy handle being used
ProtectedheaderStores current headers payload.
This will not store anything in case NoDataStorage flag is enabled
ProtectedheaderCurrent headers length.
Will always be zero in case NoDataStorage flag is enabled
ProtectedisWhether this instance is running or not (perform() was called).
Make sure to not change their value, otherwise unexpected behavior would happen.
This is marked as protected only with the TSDoc to not cause a breaking change.
ProtectedreadProtectedstreamProtectedstreamProtectedstreamProtectedstreamProtectedstreamProtectedstreamProtectedstreamProtectedstreamProtectedstreamProtectedstreamProtectedstreamProtectedstreamProtectedwriteStaticcaptureValue: 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.
StaticdefaultBy 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.defaultMaxListenersproperty can be used. If this value is not a positive number, a RangeErroris thrown.
Take caution when setting the events.defaultMaxListeners because the
change affects allEventEmitter 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 singleEventEmitter, 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'.
StaticdefaultThis is the default user agent that is going to be used on all Curl instances.
You can overwrite this in a per instance basis, calling curlHandle.setOpt('USERAGENT', 'my-user-agent/1.0'), or
by directly changing this property so it affects all newly created Curl instances.
To disable this behavior set this property to null.
Static ReadonlyerrorThis 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.
StaticgetReturns the number of handles currently open in the internal "Multi".Multi | Multi handle being used.
Returns the number of "Easy".Easy | 'Easy' handles that are currently inside this instance
StaticgetReturns libcurl version string.
The string shows which libraries libcurl was built with and their versions, example:
libcurl/7.69.1-DEV OpenSSL/1.1.1d zlib/1.2.11 WinIDN libssh2/1.9.0_DEV nghttp2/1.40.0
StaticglobalCalls curl_global_cleanup()
This is automatically called when the process is exiting.
StaticglobalCalls curl_global_init().
For flags see the the enum CurlGlobalInit.
This is automatically called when the addon is loaded, to disable this, set the environment variable
NODE_LIBCURL_DISABLE_GLOBAL_INIT_CALL=false
StaticinfoThis is a object with members resembling the CURLINFO_* libcurl constants.
It can be used with "Easy".Easy.getInfo | Easy#getInfo or Curl#getInfo.
See the official documentation of curl_easy_getinfo()
for reference.
CURLINFO_EFFECTIVE_URL becomes Curl.info.EFFECTIVE_URL
StaticoptionThis is a object with members resembling the CURLOPT_* libcurl constants.
It can be used with "Easy".Easy.setOpt | Easy#setOpt or Curl#setOpt.
See the official documentation of curl_easy_setopt()
for reference.
CURLOPT_URL becomes Curl.option.URL
StaticVERSION_Integer representing the current libcurl version.
It was built the following way:
<8 bits major number> | <8 bits minor number> | <8 bits patch number>.
Version 7.69.1 is therefore returned as 0x074501 / 476417
Whether this instance is closed or not (close() was called).
Make sure to not change their value, otherwise unexpected behavior would happen.
Optional[captureProtectedcleanupWhen uploading a stream (by calling setUploadStream)
some event listeners are attached to the stream instance.
This will remove them so our callbacks are not called anymore.
Close this handle.
NOTE: After closing the handle, it must not be used anymore. Doing so will throw an error.
Official libcurl documentation: curl_easy_cleanup()
ProtecteddefaultThis is the default callback passed to setOpt('HEADERFUNCTION', cb).
ProtecteddefaultThis is the default callback passed to setOpt('WRITEFUNCTION', cb).
ProtecteddefaultThis is used by the default callback passed to setOpt('WRITEFUNCTION', cb)
when the feature to stream response is enabled.
Disables a feature, must not be used while a request is running.
Use CurlFeature for predefined constants.
Duplicate this handle with all their options. Keep in mind that, by default, this also means all event listeners.
Official libcurl documentation: curl_easy_duphandle()
If you don't want to copy the event listeners, set this to false.
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.
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
Enables a feature, must not be used while a request is running.
Use CurlFeature for predefined constants.
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) ]
ProtectedgetReturns headers from the current stored chunks - if any
Retrieves some information about the last request made by a handle.
This overloaded method has never as type for the argument
because one of the other overloaded signatures must be used.
Official libcurl documentation: curl_easy_getinfo()
Info name or integer value. Use Curl.info for predefined constants.
Returns information about the finished connection.
Official libcurl documentation: curl_easy_getinfo()
Info to retrieve. Use "Curl".Curl.info | Curl.info for predefined constants.
Returns information about the finished connection.
Official libcurl documentation: curl_easy_getinfo()
Info to retrieve. Use "Curl".Curl.info | Curl.info for predefined constants.
Returns the current max listener value for the EventEmitter which is either
set by emitter.setMaxListeners(n) or defaults to defaultMaxListeners.
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
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] ]
This is emitted if the StreamResponse feature was enabled.
The data paramater passed to the listener callback will be one of the following:
Buffer if the feature NoDataStorage flag was enabledBuffer if the feature NoDataParsing flag was enabledThe headers parameter passed to the listener callback will be one of the following:
Buffer if the feature NoHeaderStorage flag was enabledBuffer if the feature NoHeaderParsing flag was enabledAdds 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.
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
ProtectedonProtectedCallback called when this handle has finished the request.
This is called from the internal callback we use with the "Multi".Multi.onMessage | onMessage
method of the global "Multi".Multi | Multi handle used by all Curl instances.
This should not be called in any other way.
ProtectedonProtectedCallback called when an error is thrown on this handle.
This is called from the internal callback we use with the "Multi".Multi.onMessage | onMessage
method of the global "Multi".Multi | Multi handle used by all Curl instances.
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.
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.
Optionalevent: string | symbolRemoves 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.
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.
Reset this handle options to their defaults.
This will put the handle in a clean state, as if it was just created.
Official libcurl documentation: curl_easy_reset()
ProtectedresetBy 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.
Sets an option the handle.
This overloaded method has never as type for the arguments
because one of the other overloaded signatures must be used.
Official libcurl documentation: curl_easy_setopt()
Option name or integer value. Use Curl.option for predefined constants.
The value of the option, value type depends on the option being set.
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
You can either return a single CurlHstsReadCallbackResult object or an array of CurlHstsReadCallbackResult objects.
If returning an array, the callback will only be called once per request.
If returning a single object, the callback will be called multiple times until null is returned.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
Use "Curl".Curl.option|Curl.option for predefined constants.
Official libcurl documentation: curl_easy_setopt()
The option XFERINFOFUNCTION was introduced in curl version 7.32.0,
versions older than that should use PROGRESSFUNCTION.
If you don't want to mess with version numbers you can use this method,
instead of directly calling Curl#setOpt.
NOPROGRESS should be set to false to make this function actually get called.
This sets the callback to be used as the progress function when using any of the stream features.
This is needed because when this Curl instance is enabled to use streams for upload/download, it needs
to set the libcurl progress function option to an internal function.
If you are using any of the streams features, do not overwrite the progress callback to something else,
be it using setOpt or setProgressCallback, as this would
cause undefined behavior.
If are using this callback, there is no need to set the NOPROGRESS option to false (as you normally would).
Set the param to null to use the Node.js default value.
This will passed directly to the Readable stream created to be returned as the response'
Only useful when the StreamResponse feature flag is enabled.
This will set an internal READFUNCTION callback that will read all the data from this stream.
One usage for that is to upload data directly from streams. Example:
const curl = new Curl()
curl.setOpt('URL', 'https://some-domain/upload')
curl.setOpt('UPLOAD', true)
// so we do not need to set the content length
curl.setOpt('HTTPHEADER', ['Transfer-Encoding: chunked'])
const filePath = './test.zip'
const stream = fs.createReadStream(filePath)
curl.setUploadStream(stream)
curl.setStreamProgressCallback(() => {
// this will use the default progress callback from libcurl
return CurlProgressFunc.Continue
})
curl.on('end', (statusCode, data) => {
console.log('\n'.repeat(5))
// data length should be 0, as it was sent using the response stream
console.log(
`curl - end - status: ${statusCode} - data length: ${data.length}`,
)
curl.close()
})
curl.on('error', (error, errorCode) => {
console.log('\n'.repeat(5))
console.error('curl - error: ', error, errorCode)
curl.close()
})
curl.perform()
Multiple calls with the same stream that was previously set has no effect.
Setting this to null will remove the READFUNCTION callback and disable this behavior.
ProtectedstreamThe internal function passed to PROGRESSFUNCTION (XFERINFOFUNCTION on most recent libcurl versions)
when using any of the stream features.
Perform any connection upkeep checks.
Official libcurl documentation: curl_easy_upkeep()
StaticaddExperimentalListens 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.
StaticgetReturns 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
}
StaticgetReturns an object with a representation of the current libcurl version and their features/protocols.
This is basically curl_version_info()
StaticgetReturns a string that looks like the one returned by
curl -V
Example:
Version: libcurl/7.69.1-DEV OpenSSL/1.1.1d zlib/1.2.11 WinIDN libssh2/1.9.0_DEV nghttp2/1.40.0
Protocols: dict, file, ftp, ftps, gopher, http, https, imap, imaps, ldap, ldaps, pop3, pop3s, rtsp, scp, sftp, smb, smbs, smtp, smtps, telnet, tftp
Features: AsynchDNS, IDN, IPv6, Largefile, SSPI, Kerberos, SPNEGO, NTLM, SSL, libz, HTTP2, HTTPS-proxy
StaticisStaticlistenerA class method that returns the number of listeners for the given eventNameregistered 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
Staticonimport { 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());
The name of the event being listened for
Optionaloptions: StaticEventEmitterOptionsthat iterates eventName events emitted by the emitter
StaticonceCreates 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: StaticEventEmitterOptionsCreates 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: StaticEventEmitterOptionsStaticsetimport { setMaxListeners, EventEmitter } from 'node:events';
const target = new EventTarget();
const emitter = new EventEmitter();
setMaxListeners(5, target, emitter);
Optionaln: numberA non-negative number. The maximum number of listeners per EventTarget event.
Wrapper around "Easy".Easy |
Easyclass with a more nodejs-friendly interface.This uses an internal "Multi".Multi |
Multiinstance allowing for asynchronous requests.