知识点
- stop() ：停止所有在指定元素上正在运行的动画。
- slideToggle()：通过高度变化来切换所有匹配元素的可见性，并在切换完成后可选地触发一个回调函数。
代码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>04-jQuery展开&收起动画案例-下拉菜单-界面搭建</title>
<style>
* {
padding: 0;
margin: 0;
list-style: none;
}
.firstNav {
width: 600px;
height: 44px;
margin: 100px auto;
border: 1px solid #cccccc;
cursor: pointer;
}
.firstNav>li {
width: 100px;
float: left;
text-align: center;
}
.firstNav>li>span {
display: inline-block;
width: 100%;
height: 44px;
line-height: 44px;
}
.secondNav {
border: 1px solid #cccccc;
border-top: none;
}
.secondNav>li {
margin-top: 1px;
}
.secondNav {
display: none;
}
.current .secondNav {
display: block;
}
</style>
</head>
<body>
<ul class="firstNav">
<li class="current">
<span>一级菜单1</span>
<ul class="secondNav">
<li>二级菜单1</li>
<li>二级菜单2</li>
<li>二级菜单3</li>
<li>二级菜单4</li>
<li>二级菜单5</li>
</ul>
</li>
<li>
<span>一级菜单1</span>
<ul class="secondNav">
<li>二级菜单1</li>
<li>二级菜单2</li>
<li>二级菜单3</li>
<li>二级菜单4</li>
<li>二级菜单5</li>
</ul>
</li>
<li>
<span>一级菜单1</span>
<ul class="secondNav">
<li>二级菜单1</li>
<li>二级菜单2</li>
<li>二级菜单3</li>
<li>二级菜单4</li>
<li>二级菜单5</li>
</ul>
</li>
<li>
<span>一级菜单1</span>
<ul class="secondNav">
<li>二级菜单1</li>
<li>二级菜单2</li>
<li>二级菜单3</li>
<li>二级菜单4</li>
<li>二级菜单5</li>
</ul>
</li>
<li>
<span>一级菜单1</span>
<ul class="secondNav">
<li>二级菜单1</li>
<li>二级菜单2</li>
<li>二级菜单3</li>
<li>二级菜单4</li>
<li>二级菜单5</li>
</ul>
</li>
<li>
<span>一级菜单1</span>
<ul class="secondNav">
<li>二级菜单1</li>
<li>二级菜单2</li>
<li>二级菜单3</li>
<li>二级菜单4</li>
<li>二级菜单5</li>
</ul>
</li>
</ul>
<script type="text/javascript" src="lib/jquery-3.3.1.js"></script>
<script type="text/javascript">
$(function () {
$('.firstNav>li.current .secondNav').css('display', 'none');
$('.firstNav>li').hover(function () {
$(this).children('.secondNav').stop().slideToggle(200);
});
});
</script>
</body>
</html>
运行结果：
