JS实现下拉菜单的功能

  1 <!DOCTYPE html>
  2 <html>
  3    <head>
  4        <meta charset = "utf8">
  5        <title>JS实现下拉菜单的功能</title>
  6        <style>
  7           
  8            .mynav>ul{
  9                list-style-type:none;
 10                padding:0;
 11                
 12          }
 13          .mynav>ul>li{
 14                float:left;
 15                margin:10px 20px ;
 16                color:white;
 17                
 18               }
 19          .mynav>ul>li>a{
 20             text-decoration:none;
 21             color:white;
 22             }
 23           .dropdown-m{
 24                position:absolute;
 25                z-index:99;
 26                list-style:none;
 27                margin-top:10px;
 28                padding:10px;
 29                font-size:20px;
 30                border:0px solid black;
 31                float: none;
 32                display:none;
 33                box-shadow: 10px 10px 5px #888888;
 34                background:lightblue;
 35                
 36                
 37            }
 38           
 39           .dropdown-m a{
 40                text-decoration:none;
 41                color:white;
 42                padding:10px;
 43                100px;
 44                display: block;
 45          }
 46          .dropdown-m li:hover{
 47             background:blue;
 48             
 49             
 50          }
 51          .content{
 52                margin:40px;
 53            }
 54          button{
 55                cursor: pointer;
 56                    
 57                border: none;
 58                outline: none;
 59                color: white;
 60                
 61                background-color: inherit;
 62         }
 63          .show{
 64           display:block;//用于class切换
 65            }
 66        </style>
 67    </head>
 68    <body>
 69         <div class="container" style="background:lightgrey;height:800px">
 70             <nav class="mynav" style="background:black;">
 71                <ul>
 72                   <li><a href="#">首页</a></li>
 73                   <li><a href="#">WEB</a></li>
 74                   <li><a href="#">算法</a></li>
 75                   <li >
 76                         
 77                          <button onclick="showtoggle()">前端内容</button>
 78                         
 79                       
 80                         <ul class="dropdown-m" id="dropdown">
 81                             <li><a href="#">HTML</a><li>
 82                             <li><a href="#">CSS</a><li>
 83                             <li><a href="#">JavaScript</a><li>
 84                             <li><a href="#">node.js</a><li>
 85                          </ul>
 86                  </li>
 87                </ul>
 88                <div  style="clear:both"></div>
 89                
 90             </nav>
 91              
 92             <div class="content">
 93                   <dl>
 94                       <dt>js简介<dt>
 95                       
 96                           <dd> JavaScript 是脚本语言</dd>
 97                           <dd>JavaScript 是一种轻量级的编程语言。</dd>
 98 
 99                           <dd>JavaScript 是可插入 HTML 页面的编程代码。</dd>
100 
101                           <dd> JavaScript 插入 HTML 页面后，可由所有的现代浏览器执行。</dd>
102 
103                           <dd> JavaScript 很容易学习。</dd>
104                       
105                   <dl>
106             </div>
107         </div>
108        <script>
109           //实现切换，hover也是可以，不用这么麻烦
110            function showtoggle(){
111               document.getElementById("dropdown").classList.toggle("show");
112             }
113 //点击其他区域也关闭
114           window.onclick=funtuion=function(e){
115                if(!e.target.matches("button")){
116                    var dropdown = document.getElementById("dropdown");
117                  if (dropdown.classList.contains('show')) {
118                     dropdown.classList.remove('show');
119 }}
120          }
121        </script>
122    </body>
123 </html>