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.
// First listener myEmitter.on('event', functionfirstListener() { console.log('Helloooo! first listener'); }); // Second listener myEmitter.on('event', functionsecondListener(arg1, arg2) { console.log(`event with parameters ${arg1}, ${arg2} in second listener`); }); // Third listener myEmitter.on('event', functionthirdListener(...args) { constparameters = 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 the current max listener value for the EventEmitter which is either
set by emitter.setMaxListeners(n) or defaults to EventEmitter.defaultMaxListeners.
Returns number
Since
v1.0.0
listenerCount
listenerCount<K>(eventName, listener?): 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.
Pause the websocket causing it to stop emitting events. Some events can still be
emitted after this is called, until all buffered data is consumed. This method
is a noop if the ready state is CONNECTING or CLOSED.
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.
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 new Array with a function `onceWrapper` which has a property // `listener` which contains the original listener bound above constlisteners = emitter.rawListeners('log'); constlogFnWrapper = 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 constnewListeners = emitter.rawListeners('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.
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.
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
trueif the event had listeners,falseotherwise.