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Providers

Provider Types

Section titled “Provider Types”
{ provide: AuthService, useClass: MockAuthService }  // useClass
{ provide: API_URL, useValue: 'https://api.example.com' }  // useValue
{ provide: LogLevel, useFactory: () => production ? 'error' : 'debug' }  // useFactory
{ provide: NewService, useExisting: LegacyService }  // useExisting

Registration Methods

Section titled “Registration Methods”
  1. @Injectable({ providedIn: ‘root’ }) — Tree-shakeable singleton
  2. Component providers — New instance per component
  3. Module providers — Shared within module

Summary

Section titled “Summary”

Choose the provider type and registration method based on your use case.”