Angular Web Framework Routing & Navigation 4 — Questions and Answers
Question 1: What is the purpose of enableTracing: true in RouterModule.forRoot() configuration?
- It enables source map generation for route files
- It logs all router events to the browser console for debugging (Correct answer)
- It enables performance tracing for route guards
- It activates strict route matching across the application
Correct answer: It logs all router events to the browser console for debugging
enableTracing: true outputs every router lifecycle event to the console, making it easier to debug navigation issues during development.
Question 2: Which ActivatedRoute property provides an Observable that emits the URL segments for the current route?
- route.path
- route.url (Correct answer)
- route.segments
- route.href
Correct answer: route.url
ActivatedRoute.url is an Observable<UrlSegment[]> that emits the array of URL segments matching the current route.
Question 3: How can you pass static data to a route component in Angular's route configuration?
- Using the params property in the route definition
- Using the data property in the route definition (Correct answer)
- Using the state property on the Router.navigate() extras
- Using route-level providers
Correct answer: Using the data property in the route definition
The data property in a route definition holds a static object accessible via ActivatedRoute.data, useful for passing metadata like page titles.
Question 4: What does the Angular router's scrollPositionRestoration option set to 'enabled' do?
- It restores the scroll position of individual elements after navigation
- It scrolls back to the top on forward navigation and restores position on back navigation (Correct answer)
- It disables smooth scrolling during route transitions
- It saves scroll position to localStorage between sessions
Correct answer: It scrolls back to the top on forward navigation and restores position on back navigation
With scrollPositionRestoration: 'enabled', Angular restores the saved scroll position on back/forward navigation and scrolls to the top on new navigations.
Question 5: In Angular, how would you define a wildcard route that catches all unmatched URLs?
- { path: '*', component: NotFoundComponent }
- { path: '**', component: NotFoundComponent } (Correct answer)
- { path: 'default', component: NotFoundComponent }
- { path: '', pathMatch: 'prefix', component: NotFoundComponent }
Correct answer: { path: '**', component: NotFoundComponent }
The double asterisk '**' is Angular's wildcard pattern that matches any URL not handled by prior routes; it must be the last route defined.
Question 6: What is the CanLoad guard used for in Angular routing?
- Preventing navigation to a route if a resource fails to load
- Preventing a lazy-loaded module from being downloaded if the user lacks permission (Correct answer)
- Cancelling navigation while assets are being loaded
- Blocking route activation until images are fully loaded
Correct answer: Preventing a lazy-loaded module from being downloaded if the user lacks permission
CanLoad prevents the Angular router from even downloading a lazy-loaded module's bundle if the guard returns false, saving bandwidth for unauthorized users.
Question 7: What does the router's NavigationExtras.replaceUrl option do?
- It updates the current URL without adding a new entry to the browser history stack (Correct answer)
- It replaces the entire Angular route configuration at runtime
- It changes the base URL of the application
- It strips query parameters from the URL during navigation
Correct answer: It updates the current URL without adding a new entry to the browser history stack
Setting replaceUrl: true in NavigationExtras causes the router to replace the current browser history entry instead of pushing a new one.
Angular Web Framework Routing & Navigation 4
What is the purpose of enableTracing: true in RouterModule.forRoot() configuration?