<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="/lib/bootstrap.min.css">
<script src="/lib/jquery-1.12.2.min.js"></script>
<script src="/lib/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
<h2>Dropdown Example</h2>
<div class="dropdown">
<button class="btn btn-primary dropdown-toggle" id="menu1" type="button" data-toggle="dropdown">Dropdown Example
<span class="caret"></span></button>
<ul class="dropdown-menu" role="menu" aria-labelledby="menu1">
<li role="presentation"><a role="menuitem" tabindex="-1" href="#">HTML</a></li>
<li role="presentation"><a role="menuitem" tabindex="-1" href="#">CSS</a></li>
<li role="presentation"><a role="menuitem" tabindex="-1" href="#">JavaScript</a></li>
<li role="presentation" class="divider"></li>
<li role="presentation"><a role="menuitem" tabindex="-1" href="#">About Us</a></li>
</ul>
</div><br>
<p><strong>Note:</strong> The data-toggle="dropdown" attribute is required regardless of whether you call the dropdown() method.</p>
</div>
<script>
$(document).ready(function(){
$(".dropdown-toggle").dropdown();
});
</script>
</body>
</html>