javascript 特效实现(3)—— 鼠标滑过显示二级菜单效果

1. 关键代码：使用 switch 或 if 判断语句，改变对应的二级菜单显示方式为 block 或 none

function selectTabMenu(i){
　　switch(i){
　　　　case 71:
　　　　　　document.getElementById("TabMenuCon71").style.display="block";
          document.getElementById("TabMenuCon72").style.display="none";
          document.getElementById("TabMenuCon73").style.display="none";
          document.getElementById("TabMenuCon74").style.display="none";
          document.getElementById("TabMenuCon75").style.display="none";
          document.getElementById("TabMenuCon76").style.display="none";
          break;
　　　　 　 ...
　　}
}

2. 主导航 绑定事件

<ul class="nav">
　　<li><a href="#" onmouseover="selectTabMenu(71)">首页</a></li>

3. 二级菜单

<ul id="TabMenuCon71" class="TabMenuCon">
　　<li><a href="#">公告</a></li>
　　<li><<a href="#">信息</a></li>
</ul>

4. 完整代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>水平导航-二级菜单</title>
    <style type="text/css">
        *{
            padding:0px;
            margin: 0px;
        }
        .navBar{
            height: 30px;
            background-color: #2B383E;
            text-align: center;
        }
        ul{
            list-style: none;
        }
        .nav li{
            float: left;

        }
        .nav li a{
            display: block;
            padding: 0 20px;
            height: 30px;
            line-height: 30px;
            text-decoration: none;
            color: #fff;
        }
        .nav li a:hover{
            background-color: #fff;
            color: #4DB6E7
        }
        .TabMenuCon{
            clear: both;
            display: none;
        }
        .TabMenuCon li{
            display: inline-block;
        }
    </style>

    <script type="text/javascript">
        function selectTabMenu(i){
            switch(i){
               case 71:
                document.getElementById("TabMenuCon71").style.display="block";
                document.getElementById("TabMenuCon72").style.display="none";
                document.getElementById("TabMenuCon73").style.display="none";
                document.getElementById("TabMenuCon74").style.display="none";
                document.getElementById("TabMenuCon75").style.display="none";
                document.getElementById("TabMenuCon76").style.display="none";
                break;
            case 72:
                document.getElementById("TabMenuCon71").style.display="none";
                document.getElementById("TabMenuCon72").style.display="block";
                document.getElementById("TabMenuCon73").style.display="none";
                document.getElementById("TabMenuCon74").style.display="none";
                document.getElementById("TabMenuCon75").style.display="none";
                document.getElementById("TabMenuCon76").style.display="none";
                break;
            case 73:
                document.getElementById("TabMenuCon71").style.display="none";
                document.getElementById("TabMenuCon72").style.display="none";
                document.getElementById("TabMenuCon73").style.display="block";
                document.getElementById("TabMenuCon74").style.display="none";
                document.getElementById("TabMenuCon75").style.display="none";
                document.getElementById("TabMenuCon76").style.display="none";
                break;
            case 74:
                document.getElementById("TabMenuCon71").style.display="none";
                document.getElementById("TabMenuCon72").style.display="none";
                document.getElementById("TabMenuCon73").style.display="none";
                document.getElementById("TabMenuCon74").style.display="block";
                document.getElementById("TabMenuCon75").style.display="none";
                document.getElementById("TabMenuCon76").style.display="none";
                break;
            case 75:
                document.getElementById("TabMenuCon71").style.display="none";
                document.getElementById("TabMenuCon72").style.display="none";
                document.getElementById("TabMenuCon73").style.display="none";
                document.getElementById("TabMenuCon74").style.display="none";
                document.getElementById("TabMenuCon75").style.display="block";
                document.getElementById("TabMenuCon76").style.display="none";
                break;
                case 76:
                document.getElementById("TabMenuCon71").style.display="none";
                document.getElementById("TabMenuCon72").style.display="none";
                document.getElementById("TabMenuCon73").style.display="none";
                document.getElementById("TabMenuCon74").style.display="none";
                document.getElementById("TabMenuCon75").style.display="none";
                document.getElementById("TabMenuCon76").style.display="block";
                break;
           }
        }
    </script>
</head>
<body>
    <div class="navBar">
        <ul class="nav">
            <li><a href="#" onmouseover="selectTabMenu(71)">首页</a></li>
            <li><a href="#" onmouseover="selectTabMenu(72)">关于协会</a></li>
            <li><a href="#" onmouseover="selectTabMenu(73)">协会动态</a></li>
            <li><a href="#" onmouseover="selectTabMenu(74)">协会活动</a></li>
            <li><a href="#" onmouseover="selectTabMenu(75)">会员</a></li>
            <li><a href="#" onmouseover="selectTabMenu(76)">资源空间</a></li>
        </ul>

    </div>
    <div id="TabMenuCon">
        <ul id="TabMenuCon71" class="TabMenuCon">
            <li><a href="#">公告</a></li>
            <li><<a href="#">信息</a></li>
        </ul>
        <ul id="TabMenuCon72" class="TabMenuCon">
            <li>协会简介</li>
            <li>组织机构</li>
            <li>协会章程</li>
        </ul>
        <ul id="TabMenuCon73" class="TabMenuCon">
            <li>协会新闻</li>
            <li>活动预告</li>
            <li>求职招聘</li>
        </ul>
        <ul id="TabMenuCon74" class="TabMenuCon">
            <li>义务维修月</li>
            <li>平面设计活动</li>
            <li>程序设计活动</li>
            <li>户外拓展</li>
        </ul>
        <ul id="TabMenuCon75" class="TabMenuCon">
            <li>会员登录</li>
            <li>会员注册</li>
            <li>缴纳会费</li>
            <li>会员信息管理</li>
            <li>修改密码</li>
        </ul>
        <ul id="TabMenuCon76" class="TabMenuCon">
            <li>PS教程</li>
            <li>前端设计</li>
            <li>Flash教程</li>
        </ul>
    </div>
</body>
</html>