JavaScript实现Div层缓慢收缩与展开动画

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>层收缩</title>
<script type="text/javascript">
var mh = 30;//高度
var step = 1;//每次变化的量
var ms = 10;//循环时间
function toggle(o){
 if (!o.tid)o.tid = "_" + Math.random() * 100;
 if (!window.toggler)window.toggler = {};
 if (!window.toggler[o.tid]){
  window.toggler[o.tid]={
   obj:o,
   maxHeight:o.offsetHeight,
   minHeight:mh,
   timer:null,
   action:1
  };
 }
 o.style.height = o.offsetHeight + "px";
 if (window.toggler[o.tid].timer)clearTimeout(window.toggler[o.tid].timer);
 window.toggler[o.tid].action *= -1;
 window.toggler[o.tid].timer = setTimeout("anim('"+o.tid+"')",ms );
}
function anim(id){
 var t = window.toggler[id];
 var o = window.toggler[id].obj;
 if (t.action < 0){
  if (o.offsetHeight <= t.minHeight){
   clearTimeout(t.timer);
   return;
  }
 }
 else{
  if (o.offsetHeight >= t.maxHeight){
   clearTimeout(t.timer);
   return;
  }
 }
 o.style.height = (parseInt(o.style.height, 10) + t.action * step) + "px";
 window.toggler[id].timer = setTimeout("anim('"+id+"')",ms );
}
</script>
<style type="text/css">
div.xx{
 border:solid 1px;overflow:hidden;
}
div.xx h5{
 border:solid 1px;border-width:0 0 1px;
 padding:0;margin:0;height:28px;
 line-height:30px;cursor:pointer;
 background:#eee;
}
</style>
</head>
<body>
<div class="xx"><h5 onclick="toggle(this.parentNode)">点击此处层伸缩</h5>
<p>Tomat6.0的配置视频教程，AVI电影格式，相当清淅了，比起图文版的教程更贴切，
不会配置Tomcat的网友，你可不要错过哦，由于视频抓图挺麻烦的，
试了多次还是抓了一个不太清淅的，大家将就吧。</p>
</div>
</body>
</html>