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
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) {} }
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.
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