Generic countdown timer

timer.js

// implements a reusable countdown timer
// arguments:
// upper : upper limit to start countdown at
// onStart : function to execute when the timer starts
// onInterval : function to execute every second, like update screen
// onComplete : function to execute when the timer reaches 0
// onKill : function to execute when the timer is manually killed
function countdownTimer(upper,onStart,onInterval,onComplete,onKill){
	var interval;
	
	this.interval=interval;
	this.upper=upper;
	this.iterator=upper;
	this.onStart=onStart;
	this.onInterval=onInterval;
	this.onComplete=onComplete;
	this.onKill=onKill;
}

countdownTimer.prototype.kill=function(){
	that=this;
	clearInterval(that.interval); // stop this interval
	that.onKill();	// call onKill
}

countdownTimer.prototype.start=function(){
	var that=this;

	that.onStart(); // call onstart
	that.iterator=that.upper; // set upper boundary
	that.onInterval(that.iterator); // call onInterval

	that.interval=setInterval(timer, 1000); // start timer

	function timer(){
		that.iterator--; // decrement
		that.onInterval(that.iterator); // call onInterval
		if (that.iterator === 0){ // if this is the end
			that.onComplete(); // call onComplete
			clearInterval(that.interval); // stop this interval
		}
	}
}
exports.countdownTimer=countdownTimer;

might want to make https://gist.github.com/ricardoalcocer/7443122#file-timer-js-L21 a local variable instead of a global (add var)