jQuery基于bootstrap样式库制作响应式的企业网站顶部导航下拉菜单效果，支持收缩展开，下拉显示代码。

使用方法

1、head引入css文件

<!--默认样式-->
<link rel="stylesheet" href="css/reset.css" />

<!--响应式框架-->
<link rel="stylesheet" type="text/css" href="css/bootstrap.css">

<!--主要样式-->
<link rel="stylesheet" href="css/head.css" />

2、head引入js文件

<script src="js/jquery.min.js"></script>

3、body引入HTML代码

<!-- 导航 -->
<header class="header"> 
	<div class="container clearfix"> 
		<div class="fl left">
			<a href="javascript:void(0)" ><img src="image/logo.png" alt="" class="img1" /></a>
			<a href="javascript:void(0)" ><img src="image/logo2.jpg" alt="" class="img2" /></a>
		</div>
		<div class="fr nav"> 
			<ul class="navbar_nav" data-in="fadeInDown" data-out="fadeOutUp">
				<li class="active">
					<a href="javascript:void(0)">首页</a>
				</li>
				<li class="dropdown">
					<a href="javascript:void(0)">
						业务体系
					</a>
					<div class="dropdown_menu">
						<a href="#">二级菜单</a>
						<a href="#">二级菜单</a>
						<a href="#">二级菜单</a>
					</div>
				</li>
				<li class="dropdown">
					<a href="javascript:void(0)">直营园</a>
					<div class="dropdown_menu">
						<a href="#">二级菜单</a>
						<a href="#">二级菜单</a>
						<a href="#">二级菜单</a>
					</div>
				</li>
				<li>
					<a href="javascript:void(0)">行知资讯</a>
				</li>
				<li>
					<a href="javascript:void(0)">关于我们</a>
				</li>
				<li>
					<a href="javascript:void(0)">联系合作</a>
				</li>
			</ul>
		</div>
		<a href="javascript:void(0)" id="navToggle">
			<span></span>
		</a>
	</div>
</header>
<!--移动端的导航-->
<div class="m_nav">
	<div class="top clearfix">
		<img src="image/closed.png" alt="" class="closed" />
	</div>
	<div class="logo">
		<img src="image/logo2.jpg" alt="" />
	</div>
	<ul class="ul" data-in="fadeInDown" data-out="fadeOutUp">
		<li class="active">
			<a href="javascript:void(0)">首页</a>
		</li>
		<li class="dropdown">
			<a href="javascript:void(0)">
				业务体系
			</a>
			<div class="dropdown_menu">
				<a href="#">二级菜单</a>
				<a href="#">二级菜单</a>
				<a href="#">二级菜单</a>
			</div>
		</li>
		<li class="dropdown">
			<a href="javascript:void(0)">直营园</a>
			<div class="dropdown_menu">
				<a href="#">二级菜单</a>
				<a href="#">二级菜单</a>
				<a href="#">二级菜单</a>
			</div>
		</li>
		<li>
			<a href="javascript:void(0)">行知资讯</a>
		</li>
		<li>
			<a href="javascript:void(0)">关于我们</a>
		</li>
		<li>
			<a href="javascript:void(0)">联系合作</a>
		</li>
	</ul>
</div>
<div class="banner">
	<img src="image/aa.jpg">
</div>
<div class="box" style="height: 1000px;">
	<h3 style="text-align: center; color: aliceblue">调整浏览器宽度大小查看效果</h3>
</div>

<script>
	$(function(){
		//超过一定高度导航添加类名
		var nav=$("header"); //得到导航对象  
		var win=$(window); //得到窗口对象  
		var sc=$(document);//得到document文档对象。  
		win.scroll(function(){  
		  if(sc.scrollTop()>=100){  
			nav.addClass("on");   
		  }else{  
		   nav.removeClass("on");  
		  }  
		})   

		//移动端展开nav
		$('#navToggle').on('click',function(){
			$('.m_nav').addClass('open');
		})
		//关闭nav
		$('.m_nav .top .closed').on('click',function(){
			$('.m_nav').removeClass('open');
		})
		
		//二级导航  移动端
		$(".m_nav .ul li").click(function() {
			$(this).children("div.dropdown_menu").slideToggle('slow')
			$(this).siblings('li').children('.dropdown_menu').slideUp('slow');				
		});

	})
</script>

资源出处：https://www.moyublog.com/codes/17.html