title: <div> not displaying after clicking the button
body: <p>I was expecting that after hitting the button, the <code>&lt;div id="dni"&gt;</code> would show up, however nothing is changing. What's wrong?</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html lang="en"&gt;
      &lt;head&gt;
          &lt;meta charset="utf-8"&gt;
          &lt;meta name="viewport" content="width=device-width, initial-scale=1"&gt;
          &lt;link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css"&gt;
          &lt;script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"&gt;&lt;/script&gt;
          &lt;script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"&gt;&lt;/script&gt;
  
          &lt;script&gt;
              function show_dni(){
                  $("#dni").toggle();
              }
          &lt;/script&gt;
  
      &lt;/head&gt;
      &lt;body&gt;
          &lt;div class="container"&gt;
              &lt;br&gt;&lt;br&gt;
              &lt;button class="btn btn-primary" onclick="show_dni()"&gt;Ver cliente&lt;/button&gt;
              &lt;div id="dni" class="hidden"&gt;
                  DNI: &lt;input type="text" name="id"&gt;
              &lt;/div&gt;
          &lt;/div&gt;
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Oddly, this same code works as intended on Fidd <a href="http://jsfiddle.net/wmL1zt7L/" rel="nofollow">http://jsfiddle.net/wmL1zt7L/</a></p>