juqery中循环停顿问题，求大神，加急

jquery中，for循环或者while循环中每执行一次，停顿一秒，在执行下一次循环

 function sleep(numberMillis) { 
var now = new Date(); 
var exitTime = now.getTime() + numberMillis; 
while (true) { 
now = new Date(); 
if (now.getTime() > exitTime) 
return; 
} 
}

使用
sleep(1000);

用计时器模拟for

 <script type="text/javascript" src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.4.2.min.js"></script>
<div id="dv"></div>
<script>
    var i = 0, max = 5, timer;
    function countDown() {
        $('#dv').html(i++);
        if (i >= max) clearInterval(timer)
    }
    timer = setInterval(countDown, 1000);
    countDown()
</script>

http://bbs.csdn.net/topics/390483474