timer.js

var Timer = function (finalDate, onRefresh) {
    var SECOND = 1000,
        MINUTE = 60 * SECOND,
        HOUR = 60 * MINUTE,
        DAY = 24 * HOUR;
    
    function getDelta(delta) {
        var obj = {};
        obj.days = parseInt(delta / DAY, 10);
        
        delta = delta - (obj.days*DAY);
        obj.hours = parseInt(delta / HOUR, 10);
        
        delta = delta - (obj.hours*HOUR);
        obj.minutes = parseInt(delta / MINUTE, 10);
        
        delta = delta - (obj.minutes*MINUTE);
        obj.seconds = parseInt(delta / SECOND, 10);
        
        return obj;
    }
    
    function run() {
        var now = new Date();
        var delta = finalDate.getTime() - now.getTime();
        onRefresh(getDelta(delta));
        setTimeout(run, 1000);
    }
    run();
};

/*
new Timer(myDateObject, function (delta) {
    $('#days').html(delta.days);
    $('#hours').html(delta.hours);
    $('#minutes').html(delta.minutes);
    $('#seconds').html(delta.seconds);
});
*/