title: Bootstrap 4 nested dropdown?
body: <p>What I am trying to do is if anyone click on arts then History sociology and geography submenu should show up. It should now appear when someone clicks on Arts.<br>
  <a href="https://jsfiddle.net/0e7jdfza/" rel="noreferrer">https://jsfiddle.net/0e7jdfza/</a></p>
  
  <p>I tried adding this code <a href="https://jsfiddle.net/w3zyLmgb/" rel="noreferrer">https://jsfiddle.net/w3zyLmgb/</a> in place of arts li and ul but it down work inside the dropdown though it works outside this dropdown menu</p>
  
  <pre><code>&lt;!doctype html&gt;
              &lt;html lang="en"&gt;
                &lt;head&gt;
                  &lt;!-- Required meta tags --&gt;
                  &lt;meta charset="utf-8"&gt;
                  &lt;meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no"&gt;
  
                  &lt;!-- Bootstrap CSS --&gt;
                  &lt;link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous"&gt;
  
                  &lt;title&gt;Hello, world!&lt;/title&gt;
                &lt;/head&gt;
                &lt;body&gt;        
      &lt;div class="dropdown show"&gt;
                    &lt;a class="btn btn-secondary dropdown-toggle" href="#" role="button" id="dropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false"&gt;
                      Select Streams
                    &lt;/a&gt;
                    &lt;ul class="dropdown-menu" aria-labelledby="dropdownMenuLink"&gt;
                      &lt;li&gt;&lt;a class="dropdown-item" href="#"&gt;Science&lt;/a&gt;&lt;/li&gt;
                      &lt;li&gt;&lt;a class="dropdown-item" href="#"&gt;Commerce&lt;/a&gt;&lt;/li&gt;
                      &lt;li class="nav-item dropdown"&gt;&lt;a class="dropdown-item" href="#"&gt;Arts&lt;/a&gt;
                        &lt;ul&gt;
                          &lt;li&gt;History&lt;/li&gt;
                          &lt;li&gt;Sociology&lt;/li&gt;
                          &lt;li&gt;Geogrphy&lt;/li&gt;
                        &lt;/ul&gt;
                      &lt;/li&gt;
                  &lt;/ul&gt;
                   &lt;/div&gt;
  
  
              &lt;!-- Optional JavaScript --&gt;
              &lt;!-- jQuery first, then Popper.js, then Bootstrap JS --&gt;
              &lt;script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"&gt;&lt;/script&gt;
              &lt;script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"&gt;&lt;/script&gt;
              &lt;script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"&gt;&lt;/script&gt;
            &lt;/body&gt;
          &lt;/html&gt;
  </code></pre>