What is the difference between addListener(event, listener) and on(event, listener) method in node.js?

Question

Here i cannot understand what is the basic difference between these two methods.

var events = require('events');
var eventEmitter = new events.EventEmitter();



var listner1 = function listner1() {
    console.log('listner1 executed.');
}

var listner2 = function listner2() {
    console.log('listner2 executed.');    
}

eventEmitter.addListener('connection', listner1);

eventEmitter.on('connection', listner2);

eventEmitter.emit('connection');

Answer 1

.on() is exactly the same as .addListener() in the EventEmitter object.

Straight from the EventEmitter source code:

EventEmitter.prototype.on = EventEmitter.prototype.addListener;

Sleuthing through the GitHub repository, there is this checkin from Jul 3, 2010 that contains the comment: "Experimental: 'on' as alias to 'addListener'".

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Update in 2017: The documentation for EventEmitter.prototype.addListener() now says this:

Alias for emitter.on(eventName, listener).