fidgett/DI

Dependency injection for TypeScript

DI 🎎

Custom Dependency injection for TypeScript. Was made for deeper learning Angular.

Quick usage reference

Wrap classes into Injectable decorator.

@Injectable()
class FirstService {}

@Injectable()
class SecondService {}

Use static method create in Injector class for create injector with DI scope.

const injector = Injector.create(
  [
    FirstService,
    SecondService
  ],
);

For inject one class into another, set injectable class into constructor of class where you want to inject.

@Injectable()
class SecondService {
  constructor(
    private readonly firstService: FirstService
  ) {}
}

Use method get in created injector for get some instance.

const secondService = injector.get<SecondService>(SecondService);

Provide by token

You can create token and provide class|value|factory.

const token = new InjectionToken('some description');

const injector = Injector.create(
  [
    ...
    {
      provide: token,
      useValue: 'some text'
    },
  ],
);

And for provide it into class use @Inject decorator.

@Injectable()
class SecondService {
  constructor(
    @Inject(token)
    private readonly someText: string
  ) {}
}

Multi providers

You can provide some providers by one token, then you will get array of values.

const injector = Injector.create(
  [
    ...
    {
      provide: token,
      useValue: 'some text'
    },
      {
      provide: token,
      useValue: 'some new text'
    },
  ],
);

@Injectable()
class SecondService {
  constructor(
    @Inject(token)
    private readonly someText: string
  ) {
    console.log(this.someText); // ['some text', 'some new text']
  }
}