title: How does the bootstrap navbar remove the menu button and add it?
body: <p>In a nav bar like this:</p>
  
  <p><a href="http://getbootstrap.com/examples/navbar/" rel="nofollow">http://getbootstrap.com/examples/navbar/</a></p>
  
  <p>When the window gets small enough the menu items disappear and the 3 lined button appears. I was wondering what changes are occurring when this occurs. I especially want to know what classes are added to what. My code is the following and acts like the link above. I have used inspect element but I don't see any changes occurring. Thanks!</p>
  
  <pre><code>      &lt;nav class="navbar navbar-default"&gt;
          &lt;div class="container-fluid"&gt;
            &lt;div class="navbar-header"&gt;
              &lt;button id="menuButton" type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar"&gt;
                &lt;span class="sr-only"&gt;Toggle navigation&lt;/span&gt;
                &lt;span class="icon-bar"&gt;&lt;/span&gt;
                &lt;span class="icon-bar"&gt;&lt;/span&gt;
                &lt;span class="icon-bar"&gt;&lt;/span&gt;
              &lt;/button&gt;
              &lt;h4&gt;Title&lt;/h4&gt;
            &lt;/div&gt;
                &lt;div id="navbar" class="navbar-collapse collapse"&gt;
                  &lt;ul class="nav navbar-nav"&gt;
                    &lt;li class="active"&gt;&lt;a href="#"&gt;A&lt;/a&gt;&lt;/li&gt;
                    &lt;li class=""&gt;&lt;a href="#" &gt;B&lt;/a&gt;&lt;/li&gt;
                    &lt;li class=""&gt;&lt;a href="#"  &gt;C&lt;/a&gt;&lt;/li&gt;
                  &lt;/ul&gt;
                &lt;/div&gt;&lt;!--/.nav-collapse --&gt;
              &lt;/div&gt;&lt;!--/.container-fluid --&gt;
            &lt;/nav&gt;
  </code></pre>