@dirkluijk/needle-di

Needle DI 💉

A light-weight type-safe Dependency Injection library for JavaScript and TypeScript projects

A light-weight TypeScript-first library for dependency injection.

• Stand-alone, no need to install other dependencies
• Intended for both JavaScript and TypeScript projects
• Supports three-shakeable injection tokens
• Inspired by Angular and InversifyJS
• Uses native ECMAScript TC39 decorators (currently stage 3)
• No need for experimentalDecorators and emitDecoratorMetadata
• No need for reflect-metadata or other reflection libraries

Example usage

A simple example using constructor injection:

import { injectable, inject } from '@dirkluijk/needle-di';

@injectable()
class FooService {}

@injectable()
class BarService {
    constructor(
        private fooService = inject(FooService)
    ) {}
}

By using the @injectable decorator, there is no need to register your services. Just create a new dependency injection container and request something by its token:

import { Container } from '@dirkluijk/needle-di';

const container = new Container();
const barService = container.get(BarService);

Or just:

import { bootstrap } from '@dirkluijk/needle-di';

const barService = bootstrap(BarService);

Check out the advanced examples below to learn more!

Features

• Constructor injection
• Three-shakable injection tokens
• Auto-binding using decorators
• Supports many kinds of tokens:
  • Any class reference
  • Any string or symbol
  • Any instance of InjectionToken<T> (for full type-safety)
• Supports many different providers:
  • Class references
  • Static values
  • Dynamic factories
  • Async factories
  • Multi providers
• Inheritance support

Limitations

If you rely on many advanced features, this library could be too limited. In that case, we recommend InversifyJS instead. However, if you prefer a light-weight library that works out of the box and provides full type-safety, please give it a shot!

Roadmap

• Extend the Container API
• Scoping
• ...

Please file an issue if you like to propose new features.

Installation

npm install @dirkluijk/needle-di

Advanced examples