JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.0.3/css/bootstrap.min.css">
<script src="http://netdna.bootstrapcdn.com/bootstrap/3.0.3/js/bootstrap.min.js"></script>
<input type="button" value="Add Classes" />
<div class="dropdown">
    <a data-toggle="dropdown" href="#">Dropdown Trigger</a>
    <div class="dropdown-menu">Dropdown Content</div>
</div>

JavaScript

$('input').click(function () {
    $('.dropdown').addClass('open');
    $('.dropdown').addClass('test-class');
});