Create a parser instance.
Optionalencoding: XML_Encoding | ParserOptionsnull will do content sniffing. If an object, extended parser options, and the second parameter is ignored.
Optionalseparator: string | symbol = '|'the separator for namespace URI and element/attribute name. Use XmlParser.NO_NAMESPACES to get Expat's old, broken namespace non-implementation via XmlParserCreate instead of XmlParserCreateNS.
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.
StaticCHUNK_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.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 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.
StaticNO_Use as the separator to treat namespaces in legacy mode.
StaticaddListens 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
}
StaticlistenerA 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
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());
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: StaticEventEmitterIteratorOptionsAn 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: StaticEventEmitterIteratorOptionsAn AsyncIterator that 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.
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.
StaticXML_Returns a string describing the error.
Error description in English.
StaticXML_Current expat version number.
StaticXML_Creates an XML_Parser object that can parse an external general entity; context is a '\0'-terminated string specifying the parse context; encoding is a '\0'-terminated string giving the name of the externally specified encoding, or NULL if there is no externally specified encoding. The context string consists of a sequence of tokens separated by formfeeds (\f); a token consisting of a name specifies that the general entity of the name is open; a token of the form prefix=uri specifies the namespace for a particular prefix; a token of the form =uri specifies the default namespace. This can be called at any point after the first call to an ExternalEntityRefHandler so longer as the parser has not yet been freed. The new parser is completely independent and may safely be used in a separate thread. The handlers and userData are initialized from the parser argument. Returns NULL if out of memory. Otherwise returns a new XML_Parser object.
StaticXML_Function to deallocate the model argument passed to the XML_ElementDeclHandler callback set using XML_ElementDeclHandler.
StaticXML_Get the base URI from a parser.
StaticXML_These functions return information about the current parse location. They may be called from any callback called to report some parse event; in this case the location is the location of the first of the sequence of characters that generated the event. When called from callbacks generated by declarations in the document prologue, the location identified isn't as neatly defined, but will be within the relevant markup. When called outside of the callback functions, the position indicated will be just past the last parse event (regardless of whether there was an associated callback).
They may also be called after returning from a call to XML_Parse or XML_ParseBuffer. If the return value is XML_STATUS_ERROR then the location is the location of the character at which the error was detected; otherwise the location is the location of the last parse event, as described above.
-1 on error, or byte offset.
StaticXML_These functions return information about the current parse location. They may be called from any callback called to report some parse event; in this case the location is the location of the first of the sequence of characters that generated the event. When called from callbacks generated by declarations in the document prologue, the location identified isn't as neatly defined, but will be within the relevant markup. When called outside of the callback functions, the position indicated will be just past the last parse event (regardless of whether there was an associated callback).
They may also be called after returning from a call to XML_Parse or XML_ParseBuffer. If the return value is XML_STATUS_ERROR then the location is the location of the character at which the error was detected; otherwise the location is the location of the last parse event, as described above.
0 on error, or column number.
StaticXML_These functions return information about the current parse location. They may be called from any callback called to report some parse event; in this case the location is the location of the first of the sequence of characters that generated the event. When called from callbacks generated by declarations in the document prologue, the location identified isn't as neatly defined, but will be within the relevant markup. When called outside of the callback functions, the position indicated will be just past the last parse event (regardless of whether there was an associated callback).
They may also be called after returning from a call to XML_Parse or XML_ParseBuffer. If the return value is XML_STATUS_ERROR then the location is the location of the character at which the error was detected; otherwise the location is the location of the last parse event, as described above.
0 on error, or line number.
StaticXML_If XML_Parse or XML_ParseBuffer have returned XML_STATUS_ERROR, then XML_GetErrorCode returns information about the error.
Error code
StaticXML_The user data is the first four bytes of the parser struct. #define XML_GetUserData(parser) (*(void **)(parser))
User data
StaticXML_Parse some more of the document. The string s is a buffer containing part (or perhaps all) of the document. The number of bytes of s that are part of the document is indicated by len. This means that s doesn't have to be null terminated. It also means that if len is larger than the number of bytes in the block of memory that s points at, then a memory fault is likely. The isFinal parameter informs the parser that this is the last piece of the document. Frequently, the last piece is empty (i.e. len is zero.) If a parse error occurred, it returns XML_STATUS_ERROR. Otherwise it returns XML_STATUS_OK value.
ERROR=0, OK=1, SUSPENDED=2
StaticXML_Construct a new parser. If encoding is non-null, it specifies a character encoding to use for the document. This overrides the document encoding declaration. There are four built-in encodings:
Optionalencoding: XML_EncodingParser pointer
StaticXML_Constructs a new parser that has namespace processing in effect. Namespace expanded element names and attribute names are returned as a concatenation of the namespace URI, sep, and the local part of the name. This means that you should pick a character for sep that can't be part of an URI. Since Expat does not check namespace URIs for conformance, the only safe choice for a namespace separator is a character that is illegal in XML. For instance, '\xFF' is not legal in UTF-8, and '\xFFFF' is not legal in UTF-16. There is a special case when sep is the null character '\0': the namespace URI and the local part will be concatenated without any separator - this is intended to support RDF processors. It is a programming error to use the null separator with namespace triplets.
Note: Expat does not validate namespace URIs (beyond encoding) against RFC 3986 today (and is not required to do so with regard to the XML 1.0 namespaces specification) but it may start doing that in future releases. Before that, an application using Expat must be ready to receive namespace URIs containing non-URI characters.
The ASCII number value of the separator character
The created parser
StaticXML_Free memory used by the parser. Your application is responsible for freeing any memory associated with user data.
StaticXML_Prepare a parser object to be re-used. This is particularly valuable when memory allocation overhead is disproportionately high, such as when a large number of small documnents need to be parsed. All handlers are cleared from the parser, except for the unknownEncodingHandler. The parser's external state is re-initialized except for the values of ns and ns_triplets.
Undocumented
StaticXML_Set the base URI for including external entities.
1 on success, 0 on error
StaticXML_Controls parsing of parameter entities (including the external DTD subset). If parsing of parameter entities is enabled, then references to external parameter entities (including the external DTD subset) will be passed to the handler set with XML_SetExternalEntityRefHandler. The context passed will be 0. Unlike external general entities, external parameter entities can only be parsed synchronously. If the external parameter entity is to be parsed, it must be parsed during the call to the external entity ref handler: the complete sequence of XML_ExternalEntityParserCreate, XML_Parse/XML_ParseBuffer and XML_ParserFree calls must be made during this call. After XML_ExternalEntityParserCreate has been called to create the parser for the external parameter entity (context must be 0 for this call), it is illegal to make any calls on the old parser until XML_ParserFree has been called on the newly created parser. If the library has been compiled without support for parameter entity parsing (ie without XML_DTD being defined), then XML_SetParamEntityParsing will return 0 if parsing of parameter entities is requested; otherwise it will return non-zero. Note: If XML_SetParamEntityParsing is called after XML_Parse or XML_ParseBuffer, then it has no effect and will always return 0. Note: If parser == NULL, the function will do nothing and return 0.
NEVER=0, UNLESS_STANDALONE=1, ALWAYS=2. If you want to turn this on, you probably want 1.
0 on failure
StaticXML_This function only has an effect when using a parser created with XML_ParserCreateNS, i.e. when namespace processing is in effect. The doNst flag sets whether or not prefixes are returned with names qualified with a namespace prefix. If this function is called with doNst non-zero, then afterwards namespace qualified names (that is qualified with a prefix as opposed to belonging to a default namespace) are returned as a triplet with the three parts separated by the namespace separator specified when the parser was created. The order of returned parts is URI, local name, and prefix.
If doNst is zero, then namespaces are reported in the default manner, URI then local_name separated by the namespace separator.
StaticXML_This value is passed as the userData argument to callbacks.
StaticXML_Stop the current parser.
Optionalresumable: number = 01 if resumable
0 on fail, 1 on success
Optional[captureClean up after the parser. REQUIRED, since there is not currently memory management for WASM code.
True if this is the first time destroy() was called.
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) ]
Returns the current max listener value for the EventEmitter which is either
set by emitter.setMaxListeners(n) or defaults to EventEmitter.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.
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] ]
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
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
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.
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.
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: unknownRemoves 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.
Reset the parser state, so that a new document can be parsed.
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.
Stop parsing in the middle of a document, usually from an event handler.
Optionalresumable: number = 01 for resumable
Parse an element or attribute name.
a EVENTS name, or a URI+local+prefix triple
pieces - the pieces of the name
An evented parser based on a WASM-compiled version of expat. NOTE: Please make sure to call destroy() when you are done, or ensure that you have used
usingto get explicit resource disposal (if that is supported in your environment).XmlParser