function calcage(secs, num1, num2) {
  s = ((Math.floor(secs/num1))%num2).toString();
  if (s.length < 2)
    s = "0" + s;
  return "<b>" + s + "</b>";
}

function CountBack(secs) {
  document.getElementById("cntdwn").innerHTML = 
                     calcage(secs,86400,100000) + " Days, " +
                     calcage(secs,3600,24) + ":" +
                     calcage(secs,60,60) + ":" + 
                     calcage(secs,1,60);

  setTimeout("CountBack(" + (secs-1) + ")", 990);
}

document.write("<span id='cntdwn'></span>");

if (typeof(TargetDate)=="undefined")
  TargetDate = "12/31/2020 5:00 AM";

var dthen = new Date(TargetDate);
var dnow = new Date();
ddiff = new Date(dthen-dnow);
gsecs = Math.floor(ddiff.valueOf()/1000);
CountBack(gsecs);