Count down timer using date object

Note jQuery is not needed at all for the actual counting

by fiddleyetu

HTML

<div id="counttime">02:00:01:00</div>
<div id="cons"></div>

JavaScript

function pad(num) {
      return num<10?"0"+num:num;
    }
    $(function() {
      var tCont = $('#counttime');
      var timer = tCont.html().split(':');
      
        while( timer.length < 4 ) {
          timer.unshift(0);
        }
      var endMilli = +timer[0]*864e5;
        endMilli += timer[1]*36e5;
      endMilli += timer[2]*6e4
      endMilli += timer[3]*1e3;
      if(endMilli > 0) {
        var endTime = new Date(Date.now()+endMilli);   
$("#cons").append("<br>"+endTime);
        var tId = setInterval(function() {
          var diff = endTime.getTime()-Date.now();
          if (diff<=0) {
            tCont.html("00:00:00");
            clearInterval(tId);
          }
          else {
            var d = new Date(diff),
                dd = pad( (diff - diff % (864e5))/864e5 ),
                hh = pad(d.getUTCHours()),
                mm = pad(d.getMinutes()),
                ss = pad(d.getSeconds());
              tCont.html(dd+":"+hh+":"+mm+":"+ss);
          }
        },300);      
      }
    });