Timer class for node.js

Timer.js

var events = require('events');
var util = require('util');

var EventEmitter = events.EventEmitter;

function Timer(delay, count)
{
	EventEmitter.call(this);

	count = parseInt(count)
	if(isNaN(count))
	{
		count = 1
	}

	delay = parseFloat(delay);
	if(isNaN(delay))
	{
		throw new Error('Delay must be a positive Number.');
	}

	var currentCount = 0;
	var intervalId = -1;
	var running = false;
	var self = this;

	this.__defineGetter__('currentCount', function()
	{
		return currentCount;
	});

	this.__defineGetter__('delay', function()
	{
		return delay;
	});

	this.__defineSetter__('delay', function(value)
	{
		delay = value;
		if(running)
		{
			self.stop();
			self.start();
		}
	});

	this.reset = function()
	{
		self.stop();
		currentCount = 0;
	}

	this.start = function()
	{
		if(!running)
		{
			running = true;
			clearInterval(intervalId);
			intervalId = setInterval(callback, delay);
		}
	}

	this.stop = function()
	{
		if(running)
		{
			running = false;
			clearInterval(intervalId);
		}
	}

	function callback()
	{
		currentCount++;
		self.emit('timer');
		if(currentCount >= count)
		{
			self.emit('timerComplete');
			self.reset();
		}
	}
}

util.inherits(Timer, EventEmitter);

Here's how to use it:

//Creates a timer that runs 10 times, every 100ms.
var timer = new Timer(100, 10);
timer.on('timer', function(ev)
{
    console.log('Timer fired ' + timer.currentCount);
}
timer.start();