js滑动展开与折叠效果（收缩）

需要写个js滑动展开折叠（收缩）的效果，搜索到无忧脚本的一篇贴子，稍加修改了下使其在FF也可应用，代码如下：

  
<script type="text/javascript">
//Url: http://bbs.51js.com/thread-61646-1-1.html
//Author: 风云突变
//Modify: 枫岩
var act;
function over(s,nMax){
  var obj=document.getElementById(s);
  var h = parseInt(obj.offsetHeight);
  if (h < nMax){
    obj.style.height = (h + 2)+"px";
    clearTimeout(act);
    act = setTimeout("over('"+s+"',"+nMax+")", 10);
  }
}
function out(s,nMin){
  var obj=document.getElementById(s);
  var h = parseInt(obj.offsetHeight);
  if (h > nMin){
    obj.style.height = (h - 2)+"px";
    clearTimeout(act);
    act = setTimeout("out('"+s+"',"+nMin+")", 10);
  }
}
</script>
<div id="mytd" onmouseover="over('mytd',200);" onmouseout="out('mytd',30);" style="background:#eee;">代码实例：层的滑动展开/折叠</div>

　查看滑动展开与折叠效果：

<script type="text/javascript">//Url: http://bbs.51js.com/thread-61646-1-1.html//Author: 风云突变//Modify: 枫岩var act;function over(s,nMax){  var obj=document.getElementById(s);  var h = parseInt(obj.offsetHeight);  if (h < nMax){    obj.style.height = (h + 2)+"px";    clearTimeout(act);    act = setTimeout("over('"+s+"',"+nMax+")", 10);  }}function out(s,nMin){  var obj=document.getElementById(s);  var h = parseInt(obj.offsetHeight);  if (h > nMin){    obj.style.height = (h - 2)+"px";    clearTimeout(act);    act = setTimeout("out('"+s+"',"+nMin+")", 10);  }}</script><div id="mytd" onmouseover="over('mytd',200);" onmouseout="out('mytd',30);" style="background:#eee;">代码实例：层的滑动展开/折叠</div>

无忧网友 fangxiao9159 再次优化后：

<script type="text/javascript">
var intervalId = null;
function move(id,state){
  var obj = document.getElementById(id);
  if(intervalId != null) 
    window.clearInterval(intervalId);
  function change(){
   var h = parseInt(obj.offsetHeight);
   obj.style.height = (state == "down") ? (h + 2) : (h - 2);
  }
  intervalId = window.setInterval(change,10);
}
</script>
<table border="1" cellpadding="0" cellspacing="0" id="mytd" onmouseover="move('mytd','down');" onmouseout="move('mytd','out');">
<tr><td>无忧脚本 - 风云突变</td></tr></table>

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