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延时菜单

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>JS横向延时2级下拉菜单</title>
    <style>
    body{ font-size: 12px; color: #333;}
    body, ul,h2{ margin:0;padding:0;}
    li { list-style:none;}
    a{ color: #333; text-decoration: none;}
    a:hover{ color: #f00;}
    #nav { width:100%; border:1px solid #000; margin-bottom:10px;}
    #nav li{ display:inline-block; margin:10px 20px; font-size: 16px; font-weight: bold;}
    .nav li { float:left; margin: 0 5px; font-size:12px;}
    .nav { position:absolute; border:1px solid #666; padding: 5px; display:none;}
    .n1 { left:0;}
    .n2 { left:80px;}
    .n3 { left:200px;}
    </style>
</head>
<body>
    <div class="menu">
        <ul id="nav">
          <li><a href="#">首页</a></li>
          <li><a href="#">产品中心</a></li>
          <li><a href="#">关于我们</a></li>
        </ul>
        <ul class="nav n1">
            <li><a href="#">首页二级菜单1</a></li>
            <li><a href="#">首页二级菜单2</a></li>
            <li><a href="#">首页二级菜单3</a></li>
        </ul>
        <ul class="nav n2">
            <li><a href="#">产品中心二级菜单1</a></li>
            <li><a href="#">产品中心二级菜单2</a></li>
            <li><a href="#">产品中心二级菜单3</a></li>
            <li><a href="#">产品中心二级菜单4</a></li>
        </ul>
        <ul class="nav n3">
            <li><a href="#">关于我们二级菜单1</a></li>
            <li><a href="#">关于我们二级菜单2</a></li>
        </ul>
    </div>
    <script>
    window.onload = function(){
        var oUl = document.getElementById(nav);
        var aLi = oUl.getElementsByTagName(li);    //获取一级菜单
        var aUl = document.getElementsByTagName(ul);    //获取所有ul
        var timer = null;
        var that = ‘‘;

        // 循环遍历所有的一级菜单
        for(var i = 0; i < aLi.length; i++){
            // 这里加1的原因是第0个li所对应的ul是第1个ul
            aLi[i].index = i + 1;    
            // 鼠标经过,先关闭定时器,所有2级菜单隐藏,当前2级菜单显示
            aLi[i].onmouseover = function(){
                clearTimeout(timer);
                // 这里设置i = 1也是和上面一样,一一对应
                for(var i = 1; i< aUl.length; i++){
                    aUl[i].style.display = none;
                }
                aUl[this.index].style.display = block;
            };

            // 鼠标移开时,先延时200毫秒,然后将2级菜单隐藏
            aLi[i].onmouseout = function(){
                //将当前索引值保存到that变量中
                that = this.index;
                timer = setTimeout(function(){
                    aUl[that].style.display = none;
                },200);        
            };
        }

        // 循环遍历所有的二级菜单【原理同上】
        for(var i = 1; i < aUl.length; i++){
            // 鼠标经过2级菜单,先清空定时器,当前显示
            aUl[i].onmouseover = function(){
                clearTimeout(timer);
                this.style.display = block;
            };

            // 鼠标移开2级菜单,延时200毫秒后再隐藏2级菜单
            aUl[i].onmouseout = function(){
                that = this;
                timer = setTimeout(function(){
                    that.style.display = none;
                },200);
            }
        }
    };
    </script>
</body>
</html>

 

延时菜单