5秒倒计时代码脚本

<script type="text/javascript">
var second=5;
var timer;
function change()
{
    second--;
 
 if(second>0)
 {
     document.getElementById("second").innerHTML=second;
  timer = setTimeout('change()',1000);

 }
 else
 { clearTimeout(timer); setTimeout("location.href='index.asp'");
    
 }
}
timer = setTimeout('change()',1000);
</script>