<html>
<head>
<script type="text/javascript">
window.onload =function() {
var i = 4;
setInterval(function(){
if(i == 0) {
location.href = "http://www.baidu.com/";
}
document.getElementById("test").innerHTML = i--;
},1000);
};
</script>
</head>
<body>
<span id="test">5</span>秒后自动跳转
</body>
</html>
原文：http://my.oschina.net/guomingliang/blog/301108