如何用JavaScript在页面上显示一个时间钟表?

<html>

<head>

<script type="text/javascript">

function myTime(){

var today=new Date();

var h=today.getHours();

var m=today.getMinutes();

var s=today.getSeconds();

m=checkTime(m);

s=checkTime(s);

document.getElementById('txt').innerHTML=h+":"+m+":"+s;

t=setTimeout('startTime()',500)

}

//add a '0' in front of numbers<10

function checkTime(i);

{

if(i<10)

{i="0" + 1}

return i;

}

</script>

</head>

<body onload="startTime()">

<div ></div>

</body>

</html>