on click on element add active class angular code example

Example: onclick add active class in angular

You can do something like:

<ul class="sub_modules">
  <li (click)="activateClass(subModule)"
      *ngFor="let subModule of subModules"
      [ngClass]="{'active': subModule.active}">
    <a>{{ subModule.name }}</a>
  </li>
</ul>
On The component

activateClass(subModule){
  subModule.active = !subModule.active;    
}
On the Ng class the first property is the class you wanna add and the second is the condition;