The RouterLink is a directive on the anchor tags give the router control over those elements. Since the navigation paths are fixed, you can assign string values to router-link directive as below,
<h1>Angular Router</h1>
<nav>
<a routerLink="/todosList" >List of todos</a>
<a routerLink="/completed" >Completed todos</a>
</nav>
<router-outlet></router-outlet>
