三级下拉菜单
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<script type="text/javascript" src="jquery-3.3.1.min.js"></script>
<title>三级下拉菜单</title>
<style >
*{margin: 0px;padding: 0px;}
.header{width:100%;background: #f5f5f5; }
.menu{width: 800px;height: 40px;margin: 0px auto;margin-top: 10px; background: #000;color: red;border: 1px solid #ccc;border-radius: 5px;}
.a:hover{font-size: 18px;}
ul{list-style: none;}
ul li{width: 100px;height: 40px;line-height: 40px;text-align: center;border-right: 1px solid red;cursor: pointer;float: left;}
.twobox li{width: 100px;height: 30px;line-height: 30px;background: burlywood;color: crimson;position: relative;border: 0px;}
.twobox li:hover{background: #ccc;color: darkviolet}
.three{position: absolute;left: 101px;top: 0px;}
</style>
<script>
$(document).ready(function(){
//隐藏二级与三级下拉菜单
$('.twobox').hide()
$('.three').hide()
//移上一级时显示二级菜单
$('.a').mousemove(function(){
$(this).find('.twobox').slideDown(500)
})
//移出时隐藏二级菜单
$('.a').mouseleave(function(){
$(this).find('.twobox').slideUp(500)
})
//移上二级菜单时显示三级菜单
$('.two').mousemove(function(){
$(this).find('.three').slideDown(500)
})
//移出二级菜单时隐藏三级菜单
$('.two').mouseleave(function(){
$(this).find('.three').slideUp(500)
})
})
</script>
</head>
<body>
<div class="header">
<div class="menu">
<ul class="one"> <!-- 一级下拉菜单 -->
<li class="a">首页</li>
<li class="a">产品
<ul class="twobox"> <!-- 二级下拉菜单 -->
<li>产品2.1</li>
<li class="two">产品2.2
<ul class="three"> <!-- 三级下拉菜单 -->
<li>产品3.1</li>
<li>产品3.2</li>
<li>产品3.3</li>
<li>产品3.4</li>
<li>产品3.5</li>
</ul>
</li>
<li>产品2.3</li>
<li>产品2.4</li>
<li>产品2.5</li>
</ul>
</li>
<li class="a">公司新闻</li>
<li class="a">行业新闻
<ul class="twobox"> <!-- 二级下拉菜单 -->
<li>新闻2.1</li>
<li class="two">新闻2.2
<ul class="three"> <!-- 三级下拉菜单 -->
<li>新闻3.1</li>
<li>新闻3.2</li>
</ul>
</li>
<li>新闻2.3</li>
</ul>
</li>
<li class="a">售后服务</li>
<li class="a">关于我们</li>
</ul>
</div>
</div>
</body>
</html>