Nodejs events listen and emit

eventEmitter.js

// Nodejs event listen and emit

// 不光nodejs, Javascript 本身就有 eventEmitter 
var events = require('events');

var eventEmitter = new events.EventEmitter();

var ringBell = function()
{
	console.log('ring ring ring');
};

eventEmitter.on('doorOpen', ringBell);

eventEmitter.emit('doorOpen');