title: how add class active for parent when child router link clicked in angular 5
body: <p>hi i am having the following html code</p>
  
  <pre><code>    &lt;li class="" routerLinkActive="active" [routerLinkActiveOptions]="{exact:true}"&gt;&lt;a [routerLink]="['/home']"&gt;my first tab&lt;/a&gt;&lt;/li&gt;
  
  
          &lt;li [class.active]="rla?.isActive"  routerLinkActive="active"&gt;&lt;a class="pointer"&gt;my second tab&lt;/a&gt;
  
                      &lt;ul&gt;
                          &lt;li class="" #rla="routerLinkActive" routerLinkActive="active" &gt;&lt;a [routerLink]="['/myFirstLink','rock']"&gt;Past&lt;/a&gt;&lt;/li&gt;
                          &lt;li class="" #rla="routerLinkActive" routerLinkActive="active" &gt;&lt;a [routerLink]="['/myFirstLink','aj']"&gt;Upcoming&lt;/a&gt;&lt;/li&gt;
                      &lt;/ul&gt; 
  
       &lt;/li&gt;
  &lt;/li&gt;
  </code></pre>
  
  <p>and path is</p>
  
  <pre><code>{
          path: "myFirstLink/:param",
          loadChildren: ".....
  }
  </code></pre>
  
  <p>so how to add class active for my second tab when we clicked myFirstLink with out using jquery?, my code is not working</p>