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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