倒计时代码精确到秒

<div id="TimeCounter" style="border:1px solid black;margin:1px;padding:2px;width:300px"></div>
<SCRIPT language=javascript>
<!--
function show_date_time(){
 window.setTimeout("show_date_time()", 1000);
 target=new Date(2008,8,8,20,00,00);
 today=new Date();
 timeold=(target.getTime()-today.getTime());
 
 sectimeold=timeold/1000
 secondsold=Math.floor(sectimeold);
 msPerDay=24*60*60*1000
 e_daysold=timeold/msPerDay
 daysold=Math.floor(e_daysold);
 e_hrsold=(e_daysold-daysold)*24;
 hrsold=Math.floor(e_hrsold);
 e_minsold=(e_hrsold-hrsold)*60;
 minsold=Math.floor((e_hrsold-hrsold)*60);
 seconds=Math.floor((e_minsold-minsold)*60);
 
  if (daysold<0) {
 document.getElementByIdx_x_x("TimeCounter").innerHTML="逾期,倒计时已经失效";
}
 else{
 if (daysold<10) {daysold="0"+daysold}
 if (daysold<100) {daysold="0"+daysold}
 if (hrsold<10) {hrsold="0"+hrsold}
 if (minsold<10) {minsold="0"+minsold}
 if (seconds<10) {seconds="0"+seconds}
 if (daysold<3) {
  document.getElementByIdx_x_x("TimeCounter").innerHTML="离奥运会开幕还有"+daysold+"天"+hrsold+"小时"+minsold+"分"+seconds+"秒";
}
 else
  document.getElementByIdx_x_x("TimeCounter").innerHTML="离奥运会开幕还有" + daysold+"天"+hrsold+"小时"+minsold+"分"+seconds+"秒";
}
}
show_date_time();
//-->
</SCRIPT></div>
 
***************************到某个时间自动转向另一个页面***************************************
 
<span id="span_dt_dt" style='border:1px solid black;background-color:#FFFFFF' ></span>
<script language=javascript>
<!--
function show_student163_time(){
window.setTimeout("show_student163_time()", 1000);
BirthDay=new Date("2010/11/02 11:55:00");//改成你的计时日期
today=new Date();
timeold=(BirthDay.getTime()-today.getTime());
sectimeold=timeold/1000
secondsold=Math.floor(sectimeold);
msPerDay=24*60*60*1000
e_daysold=timeold/msPerDay
daysold=Math.floor(e_daysold);
e_hrsold=(e_daysold-daysold)*24;
hrsold=Math.floor(e_hrsold);
e_minsold=(e_hrsold-hrsold)*60;
minsold=Math.floor((e_hrsold-hrsold)*60);
seconds=Math.floor((e_minsold-minsold)*60);
if(daysold>=0&&hrsold>=0&&minsold>=0&&seconds>0)
{
span_dt_dt.innerHTML=daysold+"天"+hrsold+"小时"+minsold+"分"+seconds+"秒" ;
}
else
{
 location.href="http://www.baidu.com/";
}
}
show_student163_time();
//-->
</script>