代码简介：
JS打造可折叠展开的导航菜单（Slashdot Menu）。Slashdot Menu 是从Slashdot 上发现的一个别具特色的可折叠式效果的导航菜单，可使用不同的方式配置，如哪些子菜单默认情况下是展开的，是否使用Cookies ，以及菜单展开、折叠的速度等。非常酷！
代码内容：
<!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>
<title>JS打造可折叠展开的导航菜单（Slashdot Menu）_网页代码站(www.webdm.cn)</title>
<style type="text/css">
div.sdmenu {
150px;
font-family: Arial, sans-serif;
font-size: 12px;
padding-bottom: 10px;
background: url(http://www.webdm.cn/images/20100915/bottom.gif) no-repeat right bottom;
color: #fff;
}
div.sdmenu div {
background: url(http://www.webdm.cn/images/20100915/title.gif) repeat-x;
overflow: hidden;
}
div.sdmenu div:first-child {
background: url(http://www.webdm.cn/images/20100915/toptitle.gif) no-repeat;
}
div.sdmenu div.collapsed {
height: 25px;
}
div.sdmenu div span {
display: block;
padding: 5px 25px;
font-weight: bold;
color: white;
background: url(http://www.webdm.cn/images/20100915/expanded.gif) no-repeat 10px center;
cursor: default;
border-bottom: 1px solid #ddd;
}
div.sdmenu div.collapsed span {
background-image: url(http://www.webdm.cn/images/20100915/collapsed.gif);
}
div.sdmenu div a {
padding: 5px 10px;
background: #eee;
display: block;
border-bottom: 1px solid #ddd;
color: #066;
}
div.sdmenu div a.current {
background : #ccc;
}
div.sdmenu div a:hover {
background : #066 url(http://www.webdm.cn/images/20100915/linkarrow.gif) no-repeat right center;
color: #fff;
text-decoration: none;
}
</style>
<script type="text/javascript">
function SDMenu(id) {
if (!document.getElementById || !document.getElementsByTagName)
return false;
this.menu = document.getElementById(id);
this.submenus = this.menu.getElementsByTagName("div");
this.remember = true;
this.speed = 3;
this.markCurrent = true;
this.oneSmOnly = false;
}
SDMenu.prototype.init = function() {
var mainInstance = this;
for (var i = 0; i < this.submenus.length; i++)
this.submenus[i].getElementsByTagName("span")[0].onclick = function() {
mainInstance.toggleMenu(this.parentNode);
};
if (this.markCurrent) {
var links = this.menu.getElementsByTagName("a");
for (var i = 0; i < links.length; i++)
if (links[i].href == document.location.href) {
links[i].className = "current";
break;
}
}
if (this.remember) {
var regex = new RegExp("sdmenu_" + encodeURIComponent(this.menu.id) + "=([01]+)");
var match = regex.exec(document.cookie);
if (match) {
var states = match[1].split("");
for (var i = 0; i < states.length; i++)
this.submenus[i].className = (states[i] == 0 ? "collapsed" : "");
}
}
};
SDMenu.prototype.toggleMenu = function(submenu) {
if (submenu.className == "collapsed")
this.expandMenu(submenu);
else
this.collapseMenu(submenu);
};
SDMenu.prototype.expandMenu = function(submenu) {
var fullHeight = submenu.getElementsByTagName("span")[0].offsetHeight;
var links = submenu.getElementsByTagName("a");
for (var i = 0; i < links.length; i++)
fullHeight += links[i].offsetHeight;
var moveBy = Math.round(this.speed * links.length);
var mainInstance = this;
var intId = setInterval(function() {
var curHeight = submenu.offsetHeight;
var newHeight = curHeight + moveBy;
if (newHeight < fullHeight)
submenu.style.height = newHeight + "px";
else {
clearInterval(intId);
submenu.style.height = "";
submenu.className = "";
mainInstance.memorize();
}
}, 30);
this.collapseOthers(submenu);
};
SDMenu.prototype.collapseMenu = function(submenu) {
var minHeight = submenu.getElementsByTagName("span")[0].offsetHeight;
var moveBy = Math.round(this.speed * submenu.getElementsByTagName("a").length);
var mainInstance = this;
var intId = setInterval(function() {
var curHeight = submenu.offsetHeight;
var newHeight = curHeight - moveBy;
if (newHeight > minHeight)
submenu.style.height = newHeight + "px";
else {
clearInterval(intId);
submenu.style.height = "";
submenu.className = "collapsed";
mainInstance.memorize();
}
}, 30);
};
SDMenu.prototype.collapseOthers = function(submenu) {
if (this.oneSmOnly) {
for (var i = 0; i < this.submenus.length; i++)
if (this.submenus[i] != submenu && this.submenus[i].className != "collapsed")
this.collapseMenu(this.submenus[i]);
}
};
SDMenu.prototype.expandAll = function() {
var oldOneSmOnly = this.oneSmOnly;
this.oneSmOnly = false;
for (var i = 0; i < this.submenus.length; i++)
if (this.submenus[i].className == "collapsed")
this.expandMenu(this.submenus[i]);
this.oneSmOnly = oldOneSmOnly;
};
SDMenu.prototype.collapseAll = function() {
for (var i = 0; i < this.submenus.length; i++)
if (this.submenus[i].className != "collapsed")
this.collapseMenu(this.submenus[i]);
};
SDMenu.prototype.memorize = function() {
if (this.remember) {
var states = new Array();
for (var i = 0; i < this.submenus.length; i++)
states.push(this.submenus[i].className == "collapsed" ? 0 : 1);
var d = new Date();
d.setTime(d.getTime() + (30 * 24 * 60 * 60 * 1000));
document.cookie = "sdmenu_" + encodeURIComponent(this.menu.id) + "=" + states.join("") + "; expires=" + d.toGMTString() + "; path=/";
}
};
</script>
<script type="text/javascript">
// <![CDATA[
var myMenu;
window.onload = function() {
myMenu = new SDMenu("my_menu");
myMenu.init();
};
// ]]>
</script>
</head>
<body>
<form action="#" style="font-family: sans-serif; font-size: .8em" onsubmit="return false">
<fieldset><legend>Menu actions</legend>
<label for="speed">Speed (1-5):</label>
<input type="text" id="speed" value="3" size="1" onchange="myMenu.speed = parseInt(this.value)" />
<label for="oneSmOnly">One submenu at a time:</label>
<select id="oneSmOnly" onchange="myMenu.oneSmOnly = this.selectedIndex"><option>false</option><option>true</option></select>
<select name="smNr"><option>1</option><option>2</option><option>3</option><option>4</option></select>
<input type="button" value="Expand" onclick="myMenu.expandMenu(myMenu.submenus[smNr.selectedIndex])" />
<input type="button" value="Collapse" onclick="myMenu.collapseMenu(myMenu.submenus[smNr.selectedIndex])" />
<input type="button" value="Toggle" onclick="myMenu.toggleMenu(myMenu.submenus[smNr.selectedIndex])" />
<input type="button" value="Expand all" onclick="myMenu.expandAll()" />
<input type="button" value="Collapse all" onclick="myMenu.collapseAll()" />
</fieldset>
</form>
<div style="float: left" id="my_menu" class="sdmenu">
<div>
<span>Online Tools</span>
<a href="http://tools.dynamicdrive.com/imageoptimizer/">Image Optimizer</a>
<a href="http://tools.dynamicdrive.com/favicon/">FavIcon Generator</a>
<a href="http://www.dynamicdrive.com/emailriddler/">Email Riddler</a>
<a href="http://tools.dynamicdrive.com/password/">htaccess Password</a>
<a href="http://tools.dynamicdrive.com/gradient/">Gradient Image</a>
<a href="http://tools.dynamicdrive.com/button/">Button Maker</a>
</div>
<div>
<span>Support Us</span>
<a href="http://www.dynamicdrive.com/recommendit/">Recommend Us</a>
<a href="http://www.dynamicdrive.com/link.htm">Link to Us</a>
<a href="http://www.dynamicdrive.com/resources/">Web Resources</a>
</div>
<div class="collapsed">
<span>Partners</span>
<a href="http://www.javascriptkit.com">JavaScript Kit</a>
<a href="http://www.cssdrive.com">CSS Drive</a>
<a href="http://www.codingforums.com">CodingForums</a>
<a href="http://www.dynamicdrive.com/style/">CSS Examples</a>
</div>
<div>
<span>Test Current</span>
<a href="?foo=bar">Current or not</a>
<a href="./">Current or not</a>
<a href="index.html">Current or not</a>
<a href="index.html?query">Current or not</a>
</div>
</div>
<div style="padding-left: 200px">
<pre>
var myMenu = new SDMenu("main_menu"); // ID of the menu element
// Default values...
myMenu.speed = 3; // Menu sliding speed (1 - 5 recomended)
myMenu.remember = true; // Store menu states (expanded or collapsed) in cookie and restore later
myMenu.oneSmOnly = false; // One expanded submenu at a time
myMenu.markCurrent = true; // Mark current link / page (link.href == location.href)
myMenu.init();
// Additional methods...
var firstSubmenu = myMenu.submenus[0];
myMenu.expandMenu(firstSubmenu); // Expand a submenu
myMenu.collapseMenu(firstSubmenu); // Collapse a menu
myMenu.toggleMenu(firstSubmenu); // Expand if collapsed and collapse if expanded
myMenu.expandAll(); // Expand all submenus
myMenu.collapseAll(); // Collapse all submenus
</pre>
<p></p>
<p> </p>
</div>
</body>
</html>
<br>
<p><a href="http://www.webdm.cn">网页代码站</a> - 最专业的代码下载网站 - 致力为中国站长提供有质量的代码！</p>
代码来自：http://www.webdm.cn/webcode/32ce9df5-3ebc-4766-8a79-2df15c311c8d.html