Node EventEmitter

"Talk is cheap show me the code"

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

var Ticker = function(){
    var self = this;
    EventEmitter.call(self);
    self.startTicking = function(){
        self.emit('tick');
        setTimeout(self.startTicking, 1000);
    }
}

Ticker.prototype = new EventEmitter();

var ticker = new Ticker();

ticker.startTicking();

ticker.on('tick', function(){
    console.log('got a tick');
});

Output

got a tick
(1 second delay)
got a tick
(1 second delay)
got a tick
(1 second delay)
got a ...

Explanation

First we require EventEmitter and define a Ticker class that has a method startTicking which emits an event tick every 1 second.

Then we make Ticker inherit from it(EventEmitter) by setting Ticker's prototype to an EventEmitter object. Note that we could have also used util from node like below for inheriting.

var util = require('util');
util.inherits(Ticker, EventEmitter);

After that we instansiate a Ticker object ticker and call startTicking method on it.

Finally, we add a listener for the tick event which outputs "got a tick" every time it receives a tick event.