@jsonjoy.com/di

Lightweight, dependency-free dependency injection (DI) container for Node.js and the browser. It resolves, caches, and disposes service instances across a parent–child container hierarchy, with support for singleton, scoped, and transient lifetimes and automatic lifecycle management (start/stop/dispose).

Usage

Register services against typed tokens and resolve them from a container. Each service receives the DI context (DiContext) as its first constructor argument and resolves its own dependencies via ctx.make(token); any further constructor arguments are the static arguments declared in the descriptor.

import {Container, Registry, Token, Descriptor, type DiContext} from '@jsonjoy.com/di';

const LoggerToken = Token.create<Logger>('Logger');
const ServiceToken = Token.create<Service>('Service');

class Logger {
  constructor(_ctx: DiContext) {}
  log(msg: string) {
    console.log(msg);
  }
}

class Service {
  public readonly logger: Logger;
  constructor(ctx: DiContext) {
    this.logger = ctx.make(LoggerToken);
  }
}

const registry = new Registry();
registry.set(LoggerToken, new Descriptor(Logger));
registry.set(ServiceToken, new Descriptor(Service));

const container = new Container(registry);
const service = container.make(ServiceToken);
service.logger.log('hello');

await container.dispose();

Concepts

• Token<T> — a typed identifier used to register and resolve a service.
• Descriptor<T> — describes how to construct a service: its constructor, static arguments, lifetime (singleton | scoped | transient), and ownership.
• Registry — a collection of token-to-descriptor registrations.
• Container — resolves and caches instances, manages scopes via createChild(), and disposes owned instances. Implements Printable, so a container can be printed as a tree for debugging.

Lifetimes

• singleton — one instance per container that owns the registration.
• scoped — one instance per child container (scope).
• transient — a fresh instance on every resolution.

Lifecycle

Services may implement IStartable, IStoppable, and IDisposable. The container invokes start() on resolution and stop()/dispose() (in reverse dependency order) when the container is disposed.