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.

Key Features

• 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.

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:

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:

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 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 furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.