使用Dropdown插件，你可以添加下拉菜单到任何组件，如导航栏，标签，药丸和按钮。
让我们来看看Bootstrap中的下拉插件示例-
<!DOCTYPE html>
<html>
<head>
<title>Bootstrap Example</title>
<link href = "/bootstrap/css/bootstrap.min.css" rel = "stylesheet">
<script src = "/scripts/jquery.min.js"></script>
<script src = "/bootstrap/js/bootstrap.min.js"></script>
</head>
<body>
<nav class = "navbar navbar-default" role = "navigation">
<div class = "navbar-header">
<a class = "navbar-brand" href = "#">TutorialsPoint</a>
</div>
<div id = "myexample">
<ul class = "nav navbar-nav">
<li class = "active"><a href = "#">Quiz</a></li>
<li><a href = "#">QA</a></li>
<li class = "dropdown">
<a href = "#" class = "dropdown-toggle">Tutorials <b class = "caret"></b></a>
<ul class = "dropdown-menu">
<li><a id = "action-1" href = "#">C</a></li>
<li><a href = "#">C++</a></li>
<li><a href = "#">Java</a></li>
<li class = "divider"></li>
<li><a href = "#">PHP</a></li>
<li class = "divider"></li>
<li><a href = "#">Android</a></li>
</ul>
</li>
</ul>
</div>
</nav>
<script>
$(function(){
$(".dropdown-toggle").dropdown('toggle');
});
</script>
</body>
</html>