效果：  


当前时间：2011年6月20日 星期一12:0:19 


<mce:script language="javascript"><!--
function getTimeNow() {
var time = new Date();
var hour = time.getHours();
var minute = time.getMinutes();
var second = time.getSeconds();

var week; var date;  
if(time.getDay()==0) week="星期日";  
if(time.getDay()==1) week="星期一";  
if(time.getDay()==2) week="星期二";  
if(time.getDay()==3) week="星期三";  
if(time.getDay()==4) week="星期四";  
if(time.getDay()==5) week="星期五";  
if(time.getDay()==6) week="星期六";  
date=(time.getYear())+"年"+(time.getMonth()+1)+"月"+time.getDate()+"日"+" ";  

document.getElementById("nowTime").innerHTML ="当前时间："+date+week+ hour+":"+minute+":"+second;
setTimeout("getTimeNow()",1000);

}
// --></mce:script>
 
<body οnlοad="getTimeNow()"> 关键地方。
<div ></</div>