Node.js Events Example

var events = require('events');

var eventEmit = new events.EventEmitter();

// listener1 / handler 1
var functionCalled = function(name) {
    console.log('Hi EventOccurred and functionCalled ' + name.toString())
}

// listener2 /handler 2

var functionCalled2 = function() {
    console.log('Hi Event2Occurred and functionCalled2')
}

// listener3 / handler 3

var listener3 = function() {
    console.log("Hi this is listener 3")
}

// two ways of adding (binding) listeners
eventEmit.addListener('Event2Occurred', functionCalled2);

eventEmit.on('EventOccurred', functionCalled);

// emit the above two events 
eventEmit.emit('EventOccurred', 'EventOccurred');

eventEmit.emit('Event2Occurred')

// bind the event to listener3 . We will not emit this event.

eventEmit.on('EventOccurred', listener3)


// count the listerner of an event 

countListeners = eventEmit.listenerCount('EventOccurred')

// remove the listers
eventEmit.removeListener("EventOccurred", listener3)


console.log('Total listeners of event "EventOccurred" before Removing  listener3 (Handler) :=' + countListeners)
console.log('Total listeners of event "EventOccurred" after Removing  listener3 (Handler) :=' + eventEmit.listenerCount('EventOccurred'));