<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://apps.bdimg.com/libs/bootstrap/3.3.0/css/bootstrap.min.css">
<script src="https://libs.baidu.com/jquery/2.1.4/jquery.min.js"></script>
<script src="https://apps.bdimg.com/libs/bootstrap/3.3.0/js/bootstrap.min.js"></script>
<style>
.dropdown-submenu { position: relative;
}
.dropdown-submenu .dropdown-menu { top: 0;
left: 100%;
margin-top: -1px;
}
</style>
</head>
<body>
<div class="container">
<h2>Multi-Level Dropdowns</h2>
<p>In this example, we have created a .dropdown-submenu class for multi-level dropdowns (see style section above).</p>
<p>Note that we have added jQuery to open the multi-level dropdown on click (see script section below).</p>
<div class="dropdown">
<button class="btn btn-default dropdown-toggle" type="button" data-toggle="dropdown">Tutorials
<span class="caret"></span></button>
<ul class="dropdown-menu">
<li><a tabindex="-1" href="#">HTML</a></li>
<li><a tabindex="-1" href="#">CSS</a></li>
<li class="dropdown-submenu">
<a class="test" tabindex="-1" href="#">New dropdown <span class="caret"></span></a>
<ul class="dropdown-menu">
<li><a tabindex="-1" href="#">2nd level dropdown</a></li>
<li><a tabindex="-1" href="#">2nd level dropdown</a></li>
<li class="dropdown-submenu">
<a class="test" href="#">Another dropdown <span class="caret"></span></a>
<ul class="dropdown-menu">
<li><a href="#">3rd level dropdown</a></li>
<li><a href="#">3rd level dropdown</a></li>
</ul>