哦，上面的是网上的，它的class名字写错了，应该改为
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title></title>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, minimum-scale=1.0, maximum-scale=1.0, initial=1.0, user-scalable=no, target-densitydpi=medium-dpi" />
<link href="http://apps.bdimg.com/libs/bootstrap/3.3.0/css/bootstrap.min.css" rel="stylesheet" />
<style>
.tree {
min-height: 20px;
padding: 19px;
margin-bottom: 20px;
background-color: #fbfbfb;
border: 1px solid #999;
-webkit-border-radius: 4px;
-moz-border-radius: 4px;
border-radius: 4px;
-webkit-box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.05);
-moz-box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.05);
box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.05);
}
.tree li {
list-style-type: none;
margin: 0;
padding: 10px 5px 0 5px;
position: relative;
}
.tree li::before, .tree li::after {
content: '';
left: -20px;
position: absolute;
right: auto;
}
.tree li::before {
border-left: 1px solid #999;
bottom: 50px;
height: 100%;
top: 0;
width: 1px;
}
.tree li::after {
border-top: 1px solid #999;
height: 20px;
top: 25px;
width: 25px;
}
.tree li span {
-moz-border-radius: 5px;
-webkit-border-radius: 5px;
border: 1px solid #999;
border-radius: 5px;
display: inline-block;
padding: 3px 8px;
text-decoration: none;
}
.tree li.parent_li > span {
cursor: pointer;
}
.tree > ul > li::before, .tree > ul > li::after {
border: 0;
}
.tree li:last-child::before {
height: 30px;
}
.tree li.parent_li > span:hover, .tree li.parent_li > span:hover + ul li span {
background: #eee;
border: 1px solid #94a0b4;
color: #000;
}
</style>
</head>
<body>
<div class="tree well">
<ul>
<li>
<span><i class="glyphicon glyphicon-folder-open"></i>Parent</span> <a href="">Goes somewhere</a>
<ul>
<li>
<span><i class="glyphicon glyphicon-minus-sign"></i>Child</span> <a href="">Goes somewhere</a>
<ul>
<li>
<span><i class="glyphicon glyphicon-leaf"></i>Grand Child</span> <a href="">Goes somewhere</a>
</li>
</ul>
</li>
<li>
<span><i class="glyphicon glyphicon-minus-sign"></i>Child</span> <a href="">Goes somewhere</a>
<ul>
<li>
<span><i class="glyphicon glyphicon-leaf"></i>Grand Child</span> <a href="">Goes somewhere</a>
</li>
<li>
<span><i class="glyphicon glyphicon-minus-sign"></i>Grand Child</span> <a href="">Goes somewhere</a>
<ul>
<li>
<span><i class="glyphicon glyphicon-minus-sign"></i>Great Grand Child</span> <a href="">Goes somewhere</a>
<ul>
<li>
<span><i class="glyphicon glyphicon-leaf"></i>Great great Grand Child</span> <a href="">Goes somewhere</a>
</li>
<li>
<span><i class="glyphicon glyphicon-leaf"></i>Great great Grand Child</span> <a href="">Goes somewhere</a>
</li>
</ul>
</li>
<li>
<span><i class="glyphicon glyphicon-leaf"></i>Great Grand Child</span> <a href="">Goes somewhere</a>
</li>
<li>
<span><i class="glyphicon glyphicon-leaf"></i>Great Grand Child</span> <a href="">Goes somewhere</a>
</li>
</ul>
</li>
<li>
<span><i class="glyphicon glyphicon-leaf"></i>Grand Child</span> <a href="">Goes somewhere</a>
</li>
</ul>
</li>
</ul>
</li>
<li>
<span><i class="glyphicon glyphicon-folder-open"></i>Parent2</span> <a href="">Goes somewhere</a>
<ul>
<li>
<span><i class="glyphicon glyphicon-leaf"></i>Child</span> <a href="">Goes somewhere</a>
</li>
</ul>
</li>
</ul>
</div>
<br />
<input type="button" value="打印" onclick="window.print()" />
<script src="http://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js"></script>
<script type="text/javascript">
$(function () {
$('.tree li:has(ul)').addClass('parent_li').find(' > span').attr('title', 'Collapse this branch');
$('.tree li.parent_li > span').on('click', function (e) {
var children = $(this).parent('li.parent_li').find(' > ul > li');
if (children.is(":visible")) {
children.hide('fast');
$(this).attr('title', 'Expand this branch').find(' > i').addClass('glyphicon-plus-sign').removeClass('glyphicon-minus-sign');
} else {
children.show('fast');
$(this).attr('title', 'Collapse this branch').find(' > i').addClass('glyphicon-minus-sign').removeClass('glyphicon-plus-sign');
}
e.stopPropagation();
});
});
</script>
</body>
</html>
你可以看到，css、html、js 三者的能力，有很好的体现。你的所有的前端代码设计都可以按照这个知识分布的模式来准备知识。
