js页面跳转

<span>5</span>秒后跳转到新浪网
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script type='text/javascript'>
$(document).ready(function() {
setInterval(function() {
var num = $('span').text();
--num;
if(num > 0){
$('span').text(num);
}else{
window.location.href = 'http://www.sina.com';
}
},1000);
});
</script>