@vaaas/dependency-injection

Dependency Injection Container

Very simple and minimal DI Container in Typescript.

Use DIContainer.construct to create an instance of an object, automatically wiring dependencies into its constructor.

Injectable classes objects must provide the dependencies static method that returns an array of Injectables that will be passed onto the constructor after initialisation.

Every constructed instance will be registered in the container, so it is only initialised once (Singletons).

Only synchronous construction is supported.

You can manually register injectables using DIContainer.add. This is primarily useful for registering injectables that are constructed asynchronously.

Example

class SomeRepository {
	constructor() {} // no dependencies
}

class SomeService {
	constructor(repo: SomeRepository) {
		this.repo = repo;
	}

	static dependencies() {
		return [
			SomeRepository,
		];
	}
}

const container = new DIContainer();
const service = container.construct(SomeService);

You can also override the default construction logic by registering a custom provider.

const container = new DIContainer();
container.provide(SomeRepository, () => 'arbitrary');
const service = container.construct(SomeService);
// service.repo === 'arbitrary';