JavaScript+CSS实现的可折叠二级菜单实例
本文实例讲述了JavaScript+CSS实现的可折叠二级菜单。分享给大家供大家参考，具体如下：
.aspx文件：
<%@PageLanguage="C#"AutoEventWireup="true"CodeFile="NavigateMenu.aspx.cs"Inherits="NavigateMenu"%>
<!DOCTYPEhtmlPUBLIC"-//W3C//DTDXHTML1.0Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<htmlxmlns="http://www.w3.org/1999/xhtml">
<headrunat="server">
<title>无标题页</title>
<scripttype="text/javascript"src="JScript.js"></script>
<styletype="text/css">
*{
margin:0px;
padding:0px;
border:0px;
}
#nav{
width:200px;
margin:0px;
padding:0px;
font-size:14px;
line-height:30px;
}
#navli{
width:180px;
padding-left:20px;
padding-bottom:1px;
list-style-image:none;
list-style-type:none;
background-color:#FFFFFF;
float:left;
}
#nava{
padding-left:20px;
background-color:#BFBFBF;
display:block;
text-decoration:none;
}
#nava:hover{
background-color:#FF9175;
}
#navliul{
padding-top:1px;
list-style-image:none;
list-style-type:none;
}
#navlili{
padding-left:0px;
}
#navula{
background-color:#EBEBEB;
}
.cx{
display:none;
visibility:hidden;
}
.ex{
display:inherit;
visibility:inherit;
}
</style>
<scripttype="text/javascript">
window.onload=function()
{
statUp();
}
</script>
</head>
<body>
<formid="form1"runat="server">
<divid="Parent">
<ulid="nav">
<li><ahref="javascript:void(0);"onclick="doMenu(this)">菜单1</a>
<ul>
<li><ahref="javascript:void(0);">菜单1_1</a></li>
<li><ahref="javascript:void(0);">菜单1_2</a></li>
</ul>
</li>
<li><ahref="javascript:void(0);"onclick="doMenu(this)">菜单2</a>
<ul>
<li><ahref="javascript:void(0);">菜单2_1</a></li>
<li><ahref="javascript:void(0);">菜单2_2</a></li>
</ul>
</li>
<li><ahref="javascript:void(0);"onclick="doMenu(this)">菜单3</a>
<ul>
<li><ahref="javascript:void(0);">菜单3_1</a></li>
<li><ahref="javascript:void(0);">菜单3_2</a></li>
</ul>
</li>
</ul>
</div>
</form>
</body>
</html>
js文件：
functiondoMenu(obj){
varitems=obj.parentNode.getElementsByTagName("ul");
varitmUl;
if(items.length>0){
itmUl=items[0];
}
if(itmUl.className!="ex"){
cxAll();
itmUl.className="ex";
}else{
itmUl.className="cx";
}
}
functionstatUp(){
cxAll();
}
functioncxAll(){
varulDom=document.getElementById("nav");
varitems=ulDom.getElementsByTagName("ul");
for(vari=0;i<items.length;i++)
{
items[i].className="cx";
}
}
在这里需要注意的是延迟加载的问题，由于页面加载时需要执行预处理操作statUp()方法，js单独写成一个文件或js写在<head>节点中时，需要使用window.onload=function(){执行语句;}延迟加载，不然引用DOM中对象时，会出现缺少对象错误提示。
别一种解决方法，直接将所有javaScript写在</html>
<!DOCTYPEhtmlPUBLIC"-//W3C//DTDXHTML1.0Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<htmlxmlns="http://www.w3.org/1999/xhtml">
<head>
<metahttp-equiv="Content-Type"content="text/html;charset=gb2312"/>
<title>菜单</title>
<scripttype="text/javascript"src="Untitled-3.js"></script>
<style>
*{
margin:0px;
padding:0px;
border:0px;
}
#nav{
width:200px;
margin:0px;
padding:0px;
font-size:14px;
line-height:30px;
}
#navli{
width:180px;
padding-left:20px;
padding-bottom:1px;
list-style-image:none;
list-style-type:none;
background-color:#FFFFFF;
float:left;
}
#nava{
padding-left:20px;
background-color:#BFBFBF;
display:block;
text-decoration:none;
}
#nava:hover{
background-color:#FF9175;
}
#navliul{
padding-top:1px;
list-style-image:none;
list-style-type:none;
}
#navlili{
padding-left:0px;
}
#navula{
background-color:#EBEBEB;
}
.cx{
display:none;
visibility:hidden;
}
.ex{
display:inherit;
visibility:inherit;
}
</style>
</head>
<body>
<divid="Parent">
<ulid="nav">
<li><ahref="javascript:void(0);"onclick="doMenu(this)">菜单1</a>
<ul>
<li><ahref="javascript:void(0);">菜单1_1</a></li>
<li><ahref="javascript:void(0);">菜单1_2</a></li>
</ul>
</li>
<li><ahref="javascript:void(0);"onclick="doMenu(this)">菜单2</a>
<ul>
<li><ahref="javascript:void(0);">菜单2_1</a></li>
<li><ahref="javascript:void(0);">菜单2_2</a></li>
</ul>
</li>
<li><ahref="javascript:void(0);"onclick="doMenu(this)">菜单3</a>
<ul>
<li><ahref="javascript:void(0);">菜单3_1</a></li>
<li><ahref="javascript:void(0);">菜单3_2</a></li>
</ul>
</li>
</ul>
</div>
</body>
</html>
<scripttype="text/javascript">
functiondoMenu(obj){
varitems=obj.parentNode.getElementsByTagName("ul");
varitmUl;
if(items.length>0){
itmUl=items[0];
}
if(itmUl.className!="ex"){
cxAll();
itmUl.className="ex";
}else{
itmUl.className="cx";
}
}
functionstatUp(){
cxAll();
//varulDom=document.getElementById("nav");
//varitems=ulDom.getElementsByTagName("ul");
}
functioncxAll(){
varulDom=document.getElementById("nav");
varitems=ulDom.getElementsByTagName("ul");
for(vari=0;i<items.length;i++)
{
items[i].className="cx";
}
}
statUp();
</script>
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希望本文所述对大家JavaScript程序设计有所帮助。