di

What is di?

The 'di' npm package is a lightweight dependency injection (DI) library for JavaScript and Node.js. It allows developers to manage dependencies in a modular and scalable way, which is particularly useful in large applications or when implementing inversion of control (IoC) patterns.

What are di's main functionalities?

Dependency Registration

This feature allows you to register dependencies with the injector. In the code sample, an API key is registered as a value dependency.

const Injector = require('di');
const injector = new Injector();
injector.value('apiKey', '12345');

Dependency Resolution

This feature involves resolving and injecting dependencies into services or other components. The code sample demonstrates how to resolve a 'MyService' instance with 'apiKey' injected into it.

const Injector = require('di');
const injector = new Injector();
function MyService(apiKey) { this.apiKey = apiKey; }
injector.value('apiKey', '12345');
injector.service('myService', MyService, ['apiKey']);
const myServiceInstance = injector.get('myService');

Child Injectors

Child injectors inherit dependencies from their parent injector but can also override them. This feature is useful for creating isolated scopes.

const Injector = require('di');
const parentInjector = new Injector();
const childInjector = parentInjector.createChild();
parentInjector.value('apiKey', '12345');
childInjector.get('apiKey');

Other packages similar to di

inversify

Inversify is a powerful and flexible inversion of control library for JavaScript & Node.js apps powered by TypeScript. It offers more advanced features like decorators and metadata reflection, which makes it more suitable for complex projects compared to the simpler 'di' package.

bottlejs

BottleJS is a minimalistic dependency injection micro container for JavaScript. It provides similar functionalities to 'di' but also includes middleware support and is slightly more feature-rich while still being lightweight.

awilix

Awilix is a dependency injection container for Node.js with support for ES6 Classes and a focus on modularity and testability. It differs from 'di' by offering more comprehensive configuration options and automatic resolution of dependencies.

README

Dependency Injection for Node.js

Heavily influenced by AngularJS and its implementation of dependency injection. Inspired by Guice and Pico Container.