var timer ="";
function countdown(url)
{
   var TARG_ID = "timer";
   var e = document.getElementById(TARG_ID);
   var cTicks = parseInt(e.innerHTML);
   timer = setInterval(function()
   {
      if( cTicks )
      {
         e.innerHTML = --cTicks;
      }
      else
      {
         clearInterval(timer);
         location = url;	  
      }
   }, 1000);
}

function stoptimer(){
	clearInterval(timer);
}