<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>滑動導航菜單</title>
<style>
body {margin:25px; font:12px Verdana, Arial, Helvetica}
* {padding:0; margin:0}
.dropdown {float:left; padding-right:5px}
.dropdown dt {width:188px; border:2px solid #9ac1c9; padding:8px; font-weight:bold; cursor:pointer; background:url(images/header.gif)}
.dropdown dt:hover {background:url(images/header_over.gif)}
.dropdown dd {position:absolute; overflow:hidden; width:208px; display:none; background:#fff; z-index:200; opacity:0}
.dropdown ul {width:204px; border:2px solid #9ac1c9; list-style:none; border-top:none}
.dropdown li {display:inline}
.dropdown a, .dropdown a:active, .dropdown a:visited {display:block; padding:5px; color:#333; text-decoration:none; background:#eaf0f2; width:194px}
.dropdown a:hover {background:#d9e1e4; color:#000}
.dropdown .underline {border-bottom:1px solid #b9d6dc}
</style>
<script type="text/javascript">
var DDSPEED = 10;
var DDTIMER = 15;
function ddMenu(id,d){
 var h = document.getElementById(id + '-ddheader');
 var c = document.getElementById(id + '-ddcontent');
 clearInterval(c.timer);
 if(d == 1){
  clearTimeout(h.timer);
  if(c.maxh && c.maxh <= c.offsetHeight){return}
  else if(!c.maxh){
   c.style.display = 'block';
   c.style.height = 'auto';
   c.maxh = c.offsetHeight;
   c.style.height = '0px';
  }
  c.timer = setInterval(function(){ddSlide(c,1)},DDTIMER);
 }else{
  h.timer = setTimeout(function(){ddCollapse(c)},50);
 }
}
function ddCollapse(c){
 c.timer = setInterval(function(){ddSlide(c,-1)},DDTIMER);
}
function cancelHide(id){
 var h = document.getElementById(id + '-ddheader');
 var c = document.getElementById(id + '-ddcontent');
 clearTimeout(h.timer);
 clearInterval(c.timer);
 if(c.offsetHeight < c.maxh){
  c.timer = setInterval(function(){ddSlide(c,1)},DDTIMER);
 }
}
function ddSlide(c,d){
 var currh = c.offsetHeight;
 var dist;
 if(d == 1){
  dist = (Math.round((c.maxh - currh) / DDSPEED));
 }else{
  dist = (Math.round(currh / DDSPEED));
 }
 if(dist <= 1 && d == 1){
  dist = 1;
 }
 c.style.height = currh + (dist * d) + 'px';
 c.style.opacity = currh / c.maxh;
 c.style.filter = 'alpha(opacity=' + (currh * 100 / c.maxh) + ')';
 if((currh < 2 && d != 1) || (currh > (c.maxh - 2) && d == 1)){
  clearInterval(c.timer);
 }
}
</script>
</head>
<body>
<dl class="dropdown">
 <dt id="one-ddheader" onmouseover="ddMenu('one',1)" onmouseout="ddMenu('one',-1)">源碼下載</dt>
 <dd id="one-ddcontent" onmouseover="cancelHide('one')" onmouseout="ddMenu('one',-1)">
  <ul>
   <li><a href="#" class="underline">最新源碼</a></li>
   <li><a href="#" class="underline">下載排行</a></li>
   <li><a href="#" class="underline">腳本資源</a></li>
   <li><a href="#">Ajax實例</a></li>
  </ul>
 </dd>
</dl>
<dl class="dropdown">
 <dt id="two-ddheader" onmouseover="ddMenu('two',1)" onmouseout="ddMenu('two',-1)">網(wǎng)頁特效</dt>
 <dd id="two-ddcontent" onmouseover="cancelHide('two')" onmouseout="ddMenu('two',-1)">
  <ul>
   <li><a href="#" class="underline">菜單導航</a></li>
   <li><a href="#" class="underline">層和布局</a></li>
   <li><a href="#" class="underline">圖片特效</a></li>
  </ul>
 </dd>
</dl>
</body>
</html>

希望本文所述對大家JavaScript程序設計有所幫助。

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