function Countdown() {
    var now  = new Date();
    var target = new Date("20 March, 2012");
    var time = target.getTime() - now.getTime();
    if (time > 0) {
        String.prototype.reverse = function() {return this.split('').reverse().join(''); };
        function reverse(r){return r.toString().reverse().replace(/(\d{3})/g, "$1,").reverse(); }
        document.getElementById('countdown_text').innerHTML=reverse(time);
        setTimeout(Countdown,1);
    } else { document.getElementById('countdown_text').innerHTML="the time has come"; }
}