本文实例讲述了JS基于构造函数实现的菜单滑动显隐效果。分享给大家供大家参考，具体如下：
运行效果截图如下：
具体代码如下：
<!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=utf-8" />
<meta http-equiv="Content-Type" content="; charset=utf-8" />
<title>JS树型菜单</title>
<script language="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 = 1;
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();
}
}, 10);
//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();
}
}, 10);
};
/*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.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=/";
}
};
var myMenu;
window.onload = function() {
myMenu = new SDMenu("my_menu");
myMenu.init();
};
</script>
<style type="text/css">
html,body{
height:100%;
margin:0;
font-size:12px;
}
span{
background:#F0DFBE;
border:1px solid #ffffff;
border-left:6px solid #F2A31B;
width:228px;
height:23px;
display:block;
line-height:23px;
padding-left:20px;
}
a{
padding:3px 0 3px 40px;
display:block;
color:#636363;
}
#my_menu{
width:255px;
background:#F7F2E4;
height:100%;
}
div.sdmenu div.collapsed {
height: 25px;
}
div.sdmenu div{
overflow: hidden;
}
</style>
</head>
<body>
<div style="float:left" id="my_menu" class="sdmenu">
<div>
<span>菜单一</span>
<a href="#">> 菜单一子内容</a>
<a href="#">> 菜单一子内容</a>
<a href="#">> 菜单一子内容</a>
<a href="#">> 菜单一子内容</a>
<a href="#">> 菜单一子内容</a>
</div>
<div>
<span>菜单二</span>
<a href="#">> 菜单二子内容</a>
<a href="#">> 菜单二子内容</a>
<a href="#">> 菜单二子内容</a>
</div>
<div>
<span>菜单三</span>
<a href="#">> 菜单三子内容</a>
<a href="#">> 菜单三子内容</a>
<a href="#">> 菜单三子内容</a>
</div>
<div>
<span>菜单三</span>
<a href="#">> 菜单三子内容</a>
<a href="#">> 菜单三子内容</a>
<a href="#">> 菜单三子内容</a>
</div>
<div>
<span>菜单三</span>
<a href="#">> 菜单三子内容</a>
<a href="#">> 菜单三子内容</a>
<a href="#">> 菜单三子内容</a>
</div>
<div>
<span>菜单x</span>
<a href="#">> 菜单三子内容</a>
<a href="#">> 菜单三子内容</a>
<a href="#">> 菜单三子内容</a>
</div>
</div>
</body>
</html>
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