title: Bootstrap collapse does not toggle collapsing class
body: <p>Somehow bootstrap does not toggle the <code>collapsing</code> class to activate the transition and the element to <code>collapse in</code> without <strong>any</strong> transition. My code is like this:</p>
  
  <pre><code>&lt;div class="row"&gt;
   &lt;div class=" col-lg-12 collapse" id="collapse-me"&gt;
     &lt;p&gt; some text &lt;/p&gt;
   &lt;/div&gt;
  &lt;/div&gt;
  &lt;div class="row"&gt;
    &lt;a data-toggle="collapse" data-target="#collapse-me" aria-expanded="false" aria-controls="collapse-me"&gt;Collapse this&lt;/a&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>When I test this in jsFiddle it works as expected but not on my site. My real question how can I debug this? Where can I find the listener which toggles <code>collapsing</code> class to make sure it is added and removed? </p>