JavaScript 实现5秒倒计时，接着跳转

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>Untitled Page</title>
    <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>