Angular Web Framework Services & Dependency Injection 5

Question 1

What is tree-shakable about a service declared with `@Injectable({ providedIn: 'root' })`?

Accepted Answer

The service is excluded from the bundle if nothing in the app injects it

Answer

Because the provider registration lives on the service class itself rather than in an NgModule, bundlers can detect unused services and omit them from the output.

Question 2

What happens when you use `useClass` in an Angular provider and specify a class different from the token?

Accepted Answer

Angular instantiates the specified class whenever the token is requested

Answer

useClass tells Angular to instantiate the given class when the provider token is resolved, enabling substitution of alternative implementations.

Question 3

How can you inject a service only into a component's view children, not into projected ng-content children?

Accepted Answer

Use viewProviders: [] in the @Component decorator

Answer

viewProviders registers services that are only accessible inside the component's own template, invisible to content inserted via ng-content.

Question 4

Which approach correctly provides an Angular service in a standalone component?

Accepted Answer

Add the service class to the standalone component's providers array

Answer

Standalone components support a providers array in @Component where you register services scoped to that component's injector.

Question 5

What does the `multi: true` option in an Angular provider definition do?

Accepted Answer

Causes the token to resolve to an array containing all registered values for that token

Answer

When multi: true is set, Angular collects all providers registered under the same token into an array rather than overwriting each other.

Angular Web Framework Practice Test

Angular Web Framework Practice Test

Angular Web Framework Services & Dependency Injection 5