Needle DI 💉

> A lightweight, type-safe Dependency Injection (DI) library for JavaScript and TypeScript projects.


Needle DI is a lightweight, TypeScript-first library for dependency injection (DI). It is designed to be both easy to use and highly efficient.

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- Stand-alone: No additional dependencies required
- Intended for both JavaScript-only and TypeScript projects
- Supports tree-shakeable injection tokens: optimize your builds for production.
- Inspired by Angular and InversifyJS, familiar to developers coming from these frameworks.
- Uses native ECMAScript decorators (currently stage 3)
- No need for experimentalDecorators and emitDecoratorMetadata
- No reflection libraries needed, like reflect-metadata or other reflection mechanisms.

Basic example

Here’s a simple example using constructor injection to inject one service into another.

``typescript
import { injectable, inject } from "@needle-di/core";

@injectable()
class FooService {}

@injectable()
class BarService {
constructor(private fooService = inject(FooService)) {}
// ^? Type will be inferred as FooService
}
`

The @injectable decorator eliminates the need to manually register services. To construct the BarService, create a
dependency injection container, and use the container.get() method:

`typescript
import { Container } from "@needle-di/core";

const container = new Container();
const barService = container.get(BarService);
// ^? Type will be inferred as BarService
`

Check out the docs to learn more!

Installation

`
npm install --save @needle-di/core
`

Needle DI also works with Deno and is published to JSR as well:

`bash
deno add jsr:@needle-di/core
``

Docs

Check out our docs on https://needle-di.io.

License

License under the MIT License (MIT)

Copyright (c) 2024 - 2025 Dirk Luijk

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
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The above copyright notice and this permission notice shall be included in all
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