js 下拉菜单案例

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<head>     <meta charset=”UTF-8″>     <meta name=”viewport” content=”width=device-width, initial-scale=1.0″>     <meta http-equiv=”X-UA-Compatible” content=”ie=edge”>     <title>Document</title>     <style>         * {             margin: 0;             padding: 0;         }                  li {             list-style-type: none;         }                  a {             text-decoration: none;             font-size: 14px;         }                  .nav {             margin: 100px;         }                  .nav>li {             position: relative;             float: left;             width: 80px;             height: 41px;             text-align: center;         }                  .nav li a {             display: block;             width: 100%;             height: 100%;             line-height: 41px;             color: #333;         }                  .nav>li>a:hover {             background-color: #eee;         }                  .nav ul {             display: none;             position: absolute;             top: 41px;             left: 0;             width: 100%;             border-left: 1px solid #FECC5B;             border-right: 1px solid #FECC5B;         }                  .nav ul li {             border-bottom: 1px solid #FECC5B;         }                  .nav ul li a:hover {             background-color: #FFF5DA;         }     </style> </head>

<body>     <ul class=”nav”>         <li>             <a href=”#”>微博</a>             <ul>                 <li>                     <a href=””>私信</a>                 </li>                 <li>                     <a href=””>评论</a>                 </li>                 <li>                     <a href=””>@我</a>                 </li>             </ul>         </li>         <li>             <a href=”#”>微博</a>             <ul>                 <li>                     <a href=””>私信</a>                 </li>                 <li>                     <a href=””>评论</a>                 </li>                 <li>                     <a href=””>@我</a>                 </li>             </ul>         </li>         <li>             <a href=”#”>微博</a>             <ul>                 <li>                     <a href=””>私信</a>                 </li>                 <li>                     <a href=””>评论</a>                 </li>                 <li>                     <a href=””>@我</a>                 </li>             </ul>         </li>         <li>             <a href=”#”>微博</a>             <ul>                 <li>                     <a href=””>私信</a>                 </li>                 <li>                     <a href=””>评论</a>                 </li>                 <li>                     <a href=””>@我</a>                 </li>             </ul>         </li>     </ul>     <script>         //  1 获取元素         var nav = document.querySelector(‘.nav‘);         var lis = nav.children; //得到 4个 li         // console.log(lis);         // 循环注册事件         for (var i = 0; i < lis.length; i++) {             lis[i].onmouseover = function() {                 this.children[1].style.display = ‘block‘;             }             lis[i].onmouseout = function() {                 this.children[1].style.display = ‘none‘;             }         }     </script> </body>

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