setTimeout 倒计时

<script type="text/javascript">  
//设定倒数秒数  
var t = 10;  
//显示倒数秒数  
function showTime(){  
    t -= 1;  
    document.getElementById('showtimes').innerHTML= t;  
    if(t==0){  
        location.href='error404.asp';  
    }  
    //每秒执行一次,showTime()  
    setTimeout("showTime()",1000);  
}  
//执行showTime()  
showTime();  
</script>