title: Bootstrap navbar collapse isn't working with angular4.4.4
body: <p>When I was using bootstrap3 in angular4.4.4, the bootstrap navbar collapse doesn't work, the collpased contents don't show up when I click it. Who can help me?</p>
  
  <pre><code>&lt;nav class="navbar navbar-default"&gt;
      &lt;div class="container-fluid"&gt;
          &lt;!-- Brand and toggle get grouped for better mobile display --&gt;
          &lt;a class="navbar-brand" href="#" &gt;
              &lt;img src="/assets/brand/apple-touch-icon.png" width="20" height="20" class="d-inline-block align-top" alt=""&gt;
              CottonSoft
          &lt;/a&gt;
          &lt;button type="button" class="navbar-toggle navbar-toggler-right" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1" aria-expanded="false"&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;!-- Collect the nav links, forms, and other content for toggling --&gt;
          &lt;div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1"&gt;
              &lt;ul class="nav navbar-nav"&gt;
                  &lt;li&gt;&lt;a href="#"&gt;Link&lt;/a&gt;&lt;/li&gt;
                  &lt;li class="dropdown" dropdown&gt;
                      &lt;a dropdownToggle class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false"&gt;Dropdown &lt;span class="caret"&gt;&lt;/span&gt;&lt;/a&gt;
                      &lt;ul *dropdownMenu class="dropdown-menu" role="menu"&gt;
                          &lt;li role="menuitem"&gt;&lt;a href="#"&gt;Action&lt;/a&gt;&lt;/li&gt;
                          &lt;li role="menuitem"&gt;&lt;a href="#"&gt;Another action&lt;/a&gt;&lt;/li&gt;
                          &lt;li role="menuitem"&gt;&lt;a href="#"&gt;Something else here&lt;/a&gt;&lt;/li&gt;
                          &lt;li role="separator" class="divider"&gt;&lt;/li&gt;
                          &lt;li role="menuitem"&gt;&lt;a href="#"&gt;Separated link&lt;/a&gt;&lt;/li&gt;
                      &lt;/ul&gt;
                  &lt;/li&gt;
              &lt;/ul&gt;
          &lt;/div&gt;&lt;!-- /.navbar-collapse --&gt;
      &lt;/div&gt;&lt;!-- /.container-fluid --&gt;
  &lt;/nav&gt;
  </code></pre>