function CountDown(initDate, id){    
	this.endDate = new Date(initDate);    this.countainer = document.getElementById(id);    
	this.numOfDays = [ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ];    
	this.borrowed = 0, this.years = 0, this.months = 0, this.days = 0;    
	this.hours = 0, this.minutes = 0, this.seconds = 0;    this.updateNumOfDays();    
	this.updateCounter();
}

CountDown.prototype.updateNumOfDays=function(){
	var dateNow = new Date();    
	var currYear = dateNow.getFullYear();    
	if ( (currYear % 4 == 0 && currYear % 100 != 0 ) || currYear % 400 == 0 ) {        
		this.numOfDays[1] = 29;    }    
		var self = this;
		setTimeout(function(){self.updateNumOfDays();}, (new Date((currYear+1), 1, 2) - dateNow));} 
		CountDown.prototype.datePartDiff=function(then, now, MAX){    
			var diff = now - then - this.borrowed;    this.borrowed = 0;    
			if ( diff > -1 ) return diff;    this.borrowed = 1;    
			return (MAX + diff);
		} 
		CountDown.prototype.calculate=function(){    
			var futureDate = this.endDate;    var currDate = new Date();    
			this.seconds = this.datePartDiff(currDate.getSeconds(), futureDate.getSeconds(), 60);    
			this.minutes = this.datePartDiff(currDate.getMinutes(), futureDate.getMinutes(), 60);    
			this.hours = this.datePartDiff(currDate.getHours(), futureDate.getHours(), 24);    
			this.days = this.datePartDiff(currDate.getDate(), futureDate.getDate(), 
			this.numOfDays[futureDate.getMonth()]);    
			this.months = this.datePartDiff(currDate.getMonth(), futureDate.getMonth(), 12);    
			this.years = this.datePartDiff(currDate.getFullYear(), futureDate.getFullYear(),0);} 
			CountDown.prototype.addLeadingZero=function(value){    
				return value < 10 ? ("0" + value) : value;
			} 
		CountDown.prototype.formatTime=function(){    
			this.seconds = this.addLeadingZero(this.seconds);    
			this.minutes = this.addLeadingZero(this.minutes);    
			this.hours = this.addLeadingZero(this.hours);
		} 
		CountDown.prototype.updateCounter=function(){    
			this.calculate();    
			this.formatTime();    
			this.countainer.innerHTML ="<small>Nog</small> <strong>" + this.months + "</strong> <small>" + (this.months == 1? "maand" : "maanden") + "</small>" +       
			" <strong>" + this.days + "</strong> <small>" + (this.days == 1? "dag" : "dagen") + "</small>" +       
			" <strong>" + this.hours + "</strong> <small>" + (this.hours == 1? "uur" : "uur") + "</small>" +       
			" <strong>" + this.minutes + "</strong> <small>" + (this.minutes == 1? "minuut" : "minuten") + "</small>" +       
			" <strong>" + this.seconds + "</strong> <small>" + (this.seconds == 1? "seconden" : "seconden") + "  tot 1 Januari 2012</small>";    
			if ( this.endDate > (new Date()) ) {        
				var self = this;        
				setTimeout(function(){self.updateCounter();}, 1000);
			}
} 
							
window.onload=function(){ new CountDown('January 01, 2012 00:00:00', 'countdown'); }