@angular/core

Inject

decorator

Parameter decorator on a dependency parameter of a class constructor that specifies a custom provider of the dependency.

API

@Inject(token: string);
@Inject(token: any);

Usage Notes

The following example shows a class constructor that specifies a custom provider of a dependency using the parameter decorator.

When @Inject() is not present, the injector uses the type annotation of the parameter as the provider.

class Engine {}

        @Injectable()
        class Car {
          constructor(public engine: Engine) {} // same as constructor(@Inject(Engine) engine:Engine)
        }

        const injector = Injector.create({
          providers: [
            {provide: Engine, deps: []},
            {provide: Car, deps: [Engine]},
          ],
        });
        expect(injector.get(Car).engine instanceof Engine).toBe(true);