倒计时JavaScript

来源于某网页

<font color=blue size=20>2012年春节倒计时</font>
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<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("1-23-2012");
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);
span_dt_dt.innerHTML=daysold+"天"+hrsold+"小时"+minsold+"分"+seconds+"秒" ;}
show_student163_time();//-->
</SCRIPT>