在计算机应用中，下拉式选单是选单的一种表现形式。具体表现为：当用户选中一个选项后，该选单会向下延伸出具有其他选项的另一个选单。下拉式选单通常应用于把一些具有相同分类的功能放在同一个下拉式选单中，并把这个下拉式选单置于主选单的一个选项下。下拉菜单内的项目可以据需要设置为多选或单选，可以用来替代一组复选框（设置为多选）或单选框（设置为单选）。这样比复选框组或单选框组的占用位置小，但不如它们直观。
本文通过实例代码给大家讲解了jQuery实现下拉菜单效果,非常不错，具有参考借鉴价值，需要的朋友可以参考下
基本效果是这样的~~
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
<style type="text/css">
* {
margin: 0;
padding: 0;
}
ul {
list-style: none;
}
.wrap {
width: 330px;
height: 30px;
margin: 100px auto 0;
padding-left: 10px;
background-color: skyblue;
}
.wrap li {
background-color: skyblue;
}
.wrap > ul > li {
float: left;
margin-right: 10px;
position: relative;
}
.wrap a {
display: block;
height: 30px;
width: 100px;
text-decoration: none;
color: #000;
line-height: 30px;
text-align: center;
}
.wrap li ul {
position: absolute;
top: 30px;
display: none;
}
</style>
<script src="http://apps.bdimg.com/libs/jquery/2.1.4/jquery.js"></script>
<script>
$(function () {
//获取所有li，添加移入事件
$(".wrap>ul>li").mouseenter(function () {
//设置内部的子元素ul slideDown
$(this).children("ul").stop().slideDown(600);
});
//移出li时，让内部子元素slideUp
$(".wrap>ul>li").mouseleave(function () {
$(this).children("ul").stop().slideUp(600);
});
//如果当前运动没有完毕，又添加了新的动画，这时新的动画需要等待当前动画执行完毕才会开始
//如果持续添加。一定会造成动画的积累，这种情况我们称为动画队列
});
</script>
</head>
<body>
<p class="wrap">
<ul>
<li>
<a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >一级菜单1</a>
<ul class="ul">
<li><a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >二级菜单11</a></li>
<li><a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >二级菜单12</a></li>
<li><a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >二级菜单13</a></li>
</ul>
</li>
<li>
<a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >一级菜单2</a>
<ul>
<li><a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >二级菜单21</a></li>
<li><a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >二级菜单22</a></li>
<li><a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >二级菜单23</a></li>
</ul>
</li>
<li>
<a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >一级菜单3</a>
<ul>
<li><a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >二级菜单31</a></li>
<li><a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >二级菜单32</a></li>
<li><a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >二级菜单33</a></li>
</ul>
</li>
</ul>
</p>
</body>
</html>以上所述是小编给大家介绍的jQuery实现下拉菜单的实例代码，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持！
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