Dependency Injection Lifetimes (Frontend)

Angular uses hierarchical injectors to control service lifetimes.

Common scopes

• Root providers: Singleton for the entire app.
• Module/feature providers: Singleton per feature boundary.
• Component providers: New instance per component instance.

Testing tips

• Provide mocks in TestBed for unit tests.
• Use component-level providers to isolate state.

Interview prompt

• When would you scope a service at the component level?