<html><head><script type="text/javascript">function startTime(){var today=new Date()var h=today.getHours()var m=today.getMinutes()var s=today.getSeconds()// add a zero in front of numbers<10m=checkTime(m)s=checkTime(s)document.getElementById(‘txt‘).innerHTML=h+":"+m+":"+st=setTimeout(‘startTime()‘,500)}function checkTime(i){if (i<10) ??{i="0" + i} ?return i}</script></head><body onload="startTime()"><div id="txt"></div></body></html>setTimeout（function，n）表示的是在n毫秒之后执行function这个方法或者是代码。
JS时钟
原文地址：http://www.cnblogs.com/xmlys/p/7525721.html