HeroDetailComponent has a “Back” button wired to its
gotoHeroes method that navigates imperatively back to the
navigate method takes the same one-item link parameters array that you can bind to a
[routerLink] directive. It holds the path to the
Route Parameters: Required or optional?
Use route parameters to specify a required parameter value within the route URL as you do when navigating to the HeroDetailComponent in order to view the hero with id 15: