What is Dependency Injection?

Dependency Injection (DI) is a design pattern in Angular that allows classes to receive dependencies from external sources rather than creating them internally. This promotes loose coupling, testability, and reusability.

  • Key Benefits
    • Easier to test with mock objects
    • Improved modularity and maintainability
    • Simplified code structure through inversion of control
Angular DI Illustration

How DI Works in Angular

Angular uses the @Injectable decorator to mark classes as providers. Dependencies are injected via constructors or the useValue property.

  • Example Code 
    @Injectable()
class Logger {
  log(message: string) {
    console.log(message);
  }
}

class MyService {
  constructor(private logger: Logger) {}
}
Angular DI Flow

Best Practices for DI

  • Use providedIn: 'root' for singleton services
  • Avoid deep dependency chains
  • Prefer constructor injection over other methods

For deeper insights, check our Angular DI Documentation or explore advanced topics like Angular Providers and Scope.

DI Best Practices

🌐 Extend Your Knowledge

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