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>