demo node event emitter

app.js

/*
 * app.js
 * @toanalien
 */

var Emitter = require('./emitter');
var emtr = new Emitter();

emtr.on('sayhello', function() {
    console.log('hello world !');
});

emtr.on('sayhello', function() {
    console.log('hello everybody !');
});

console.log('demo node event emitter');
emtr.emit('sayhello');

/*
 * output
 * demo node event emitter
 * hello world !
 * hello everybody !
 */

emitter.js

/*
 * emitter.js
 * @toanalien
 */

function Emitter() {
    this.events = {}; // khoi tao doi tuong events
}

Emitter.prototype.on = function(type, listener) {
    this.events[type] = this.events[type] || []; // neu properties events[type] chua ton tai, khoi tao arr events[type]
    this.events[type].push(listener); // them listener vao arr
}

Emitter.prototype.emit = function(type) {
    if (this.events[type]) { // kiem tra su ton tai cua properties events[type] 
        this.events[type].forEach(function(listener) {
            listener(); // goi listener
        });
    }
}

module.exports = Emitter;