注：setInterval和setTimeout的区别
setInterval是按照设置的时间无限次数的刷新
setTimeout是按照设置的时间值刷新一次
所以例二setTimeout实现了递归回调
<head>
<title>无标题页</title>
<script type="text/javascript">
function sa()
{
var Time=new Date();
document.getElementById("div").innerHTML=Time.getSeconds();
}
window.setInterval("sa()",1000);
</script>
</head>
<body>
<div id="div">
</div>
</body>
====================================================================
或者
<head>
<title>无标题页</title>
<script type="text/javascript">
function sa()
{
var Time=new Date();
document.getElementById("div").innerHTML=Time.getSeconds();
setTimeout("sa()",1000);
}
window.setTimeout("sa()",1000);
</script>
</head>
<body>
<div id="div">
</div>
</body>