Event: 'exit' code <Number> the exit code if the child exited on its own. signal <String> the signal by which the child process was terminated. The 'exit' event is emitted after the child process ends. If the process exited, code is the final exit code of the process, otherwise null. If the process terminated due to receipt of a signal, signal is the string name of the signal, otherwise null. One of the two will always be non-null. Note that when the 'exit' event is triggered,

emitter.setMaxListeners(n) 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. Obviously, not all events should be limited to just 10 listeners. The emitter.setMaxListeners() method allows the limit to be modified for this specific EventEmitter instance. The value can be set to Infinity (or 0) for to indicate an unlimited number of listeners. Returns a reference to the EventEmitter s

emitter.removeAllListeners([eventName]) Removes all listeners, or those of the specified eventName. Note that 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 calls can be chained.

emitter.removeListener(eventName, listener) Removes the specified listener from the listener array for the event named eventName. var 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 removeLis

emitter.once(eventName, listener) Adds a one time listener function for the event named eventName. This listener is invoked only the next time eventName is triggered, after which it is removed. server.once('connection', (stream) => { console.log('Ah, we have our first user!'); }); Returns a reference to the EventEmitter so calls can be chained.

emitter.emit(eventName[, arg1][, arg2][, ...]) 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.

emitter.getMaxListeners() Returns the current max listener value for the EventEmitter which is either set by emitter.setMaxListeners(n) or defaults to EventEmitter.defaultMaxListeners.

emitter.listeners(eventName) 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] ]

emitter.listenerCount(eventName) eventName <Value> The name of the event being listened for Returns the number of listeners listening to the event named eventName.

emitter.on(eventName, listener) 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 calls can be chained.