<h1 align="center">Dioma</h1> <img src="https://github.com/zheksoon/dioma/blob/main/assets/dioma-logo.webp?raw=true" alt="dioma" width="200" /> Elegant dependency injection container for vanilla JavaScript and TypeScript <img alt="NPM Version" src="https://img.shields.io/npm/v/dioma?style=flat-square&color=%2364d4c1&link=https%3A%2F%2Fwww.npmjs.com%2Fpackage%2Fdioma"> <img alt="NPM package gzipped size" src="https://img.shields.io/bundlejs/size/dioma?style=flat-square&label=gzip&color=%2364d4c1"> <img alt="Codecov" src="https://img.shields.io/codecov/c/github/zheksoon/dioma?style=flat-square&color=%2364d4c1">

Features

Just do it - no decorators, no annotations, no magic
Tokens for class, value, and factory injection
Async injection and dependency cycle detection
TypeScript support
No dependencies
Tiny size

Installation

npm install --save dioma

yarn add dioma

Usage

To start injecting dependencies, you just need to add the static scope property to your class and use the inject function to get the instance of it. By default, inject makes classes "stick" to the container where they were first injected (more details in the Class registration section).

Here's an example of using it for Singleton and Transient scopes:

import { inject, Scopes } from "dioma";

class Garage {
  open() {
    console.log("garage opened");
  }

  // Single instance of the class for the entire application
  static scope = Scopes.Singleton();
}

class Car {
  // injects instance of Garage
  constructor(private garage = inject(Garage)) {}

  park() {
    this.garage.open();
    console.log("car parked");
  }

  // New instance of the class on every injection
  static scope = Scopes.Transient();
}

// Creates a new Car and injects Garage
const car = inject(Car);

car.park();

Scopes

Dioma supports the following scopes:

Scopes.Singleton() - creates a single instance of the class
Scopes.Transient() - creates a new instance of the class on every injection
Scopes.Container() - creates a single instance of the class per container
Scopes.Resolution() - creates a new instance of the class every time, but the instance is the same for the entire resolution
Scopes.Scoped() is the same as Scopes.Container()

Singleton scope

Singleton scope creates a single instance of the class for the entire application. The instances are stored in the global container, so anyone can access them. If you want to isolate the class to a specific container, use the Container scope.

A simple example you can see in the Usage section.

Multiple singletons can be cross-referenced with each other using async injection.

Transient scope

Transient scope creates a new instance of the class on every injection:

import { inject, Scopes } from "dioma";

class Engine {
  start() {
    console.log("Engine started");
  }

  static scope = Scopes.Singleton();
}

class Vehicle {
  constructor(private engine = inject(Engine)) {}

  drive() {
    this.engine.start();
    console.log("Vehicle driving");
  }

  static scope = Scopes.Transient();
}

// New vehicle every time
const vehicle = inject(Vehicle);

vehicle.drive();

Generally, transient scope instances can't be cross-referenced by the async injection with some exceptions.

Container scope

Container scope creates a single instance of the class per container. It's the same as the singleton, but relative to the custom container.

The usage is the same as for the singleton scope, but you need to create a container first and use container.inject instead of inject:

import { Container, Scopes } from "dioma";

const container = new Container();

class Garage {
  open() {
    console.log("garage opened");
  }

  // Single instance of the class for the container
  static scope = Scopes.Container();
}

// Register Garage on the container
container.register({ class: Garage });

class Car {
  // Use inject method of the container for Garage
  constructor(private garage = container.inject(Garage)) {}

  park() {
    this.garage.open();
    console.log("car parked");
  }

  // New instance on every injection
  static scope = Scopes.Transient();
}

const car = container.inject(Car);

car.park();

Container-scoped classes usually are registered in the container first. Without it, the class will "stick" to the container it's used in.

Resolution scope

Resolution scope creates a new instance of the class every time, but the instance is the same for the entire resolution:

import { inject, Scopes } from "dioma";

class Query {
  static scope = Scopes.Resolution();
}

class RequestHandler {
  constructor(public query = inject(Query)) {}

  static scope = Scopes.Resolution();
}

class RequestUser {
  constructor(
    public request = inject(RequestHandler),
    public query = inject(Query)
  ) {}

  static scope = Scopes.Transient();
}

const requestUser = inject(RequestUser);

// The same instance of Query is used for each of them
requestUser.query === requestUser.request.query;

Resolution scope instances can be cross-referenced by the async injection without any issues.

Injection with arguments

You can pass arguments to the constructor when injecting a class:

import { inject, Scopes } from "dioma";

class Owner {
  static scope = Scopes.Singleton();

  petSomebody(pet: Pet) {
    console.log(`${pet.name} petted`);
  }
}

class Pet {
  constructor(public name: string, public owner = inject(Owner)) {}

  pet() {
    this.owner.petSomebody(this);
  }

  static scope = Scopes.Transient();
}

const pet = inject(Pet, "Fluffy");

pet.pet(); // Fluffy petted

Only transient and resolution scopes support argument injection. Resolution scope instances are cached for the entire resolution, so the arguments are passed only once.

Class registration

By default, Scopes.Container class injection is "sticky" - the class sticks to the container where it was first injected.

If you want to make a class save its instance in some specific parent container (see Child containers), you can use class registration:

const container = new Container();

const child = container.childContainer();

class FooBar {
  static scope = Scopes.Container();
}

// Register the Foo class in the parent container
container.register({ class: FooBar });

// Returns and cache the instance on parent container
const foo = container.inject(FooBar);

// Returns the FooBar instance from the parent container
const bar = child.inject(FooBar);

foo === bar; // true

You can override the scope of the registered class:

container.register({ class: FooBar, scope: Scopes.Transient() });

To unregister a class, use the unregister method:

container.unregister(FooBar);

After that, the class will be removed from the container and all its child containers, and the next injection will return a new instance.

Injection with tokens

Instead of passing a class to the inject, you can use tokens instead. The token injection can be used for class, value, and factory injection. Here's detailed information about each type.

Class tokens

Class tokens are useful to inject an abstract class or interface that has multiple implementations:

<details> <summary>Here is an example of injecting an abstract interface</summary>

import { Token, Scopes, globalContainer } from "dioma";

const wild = globalContainer.childContainer("Wild");

const zoo = wild.childContainer("Zoo");

interface IAnimal {
  speak(): void;
}

class Dog implements IAnimal {
  speak() {
    console.log("Woof");
  }

  static scope = Scopes.Container();
}

class Cat implements IAnimal {
  speak() {
    console.log("Meow");
  }

  static scope = Scopes.Container();
}

const animalToken = new Token<IAnimal>("Animal");

// Register Dog class with the token
wild.register({ token: animalToken, class: Dog });

// Register Cat class with the token
zoo.register({ token: animalToken, class: Cat });

// Returns Dog instance
const wildAnimal = wild.inject(animalToken);

// Returns Cat instance
const zooAnimal = zoo.inject(animalToken);

</details>

The class token registration can also override the scope of the class:

wild.register({ token: animalToken, class: Dog, scope: Scopes.Transient() });

Value tokens

Value tokens are useful to inject a constant value:

import { Token } from "dioma";

const token = new Token<string>("Value token");

container.register({ token, value: "Value" });

const value = container.inject(token);

console.log(value); // Value

Factory tokens

Factory tokens are useful to inject a factory function. The factory takes the current container as the first argument and returns a value:

import { Token } from "dioma";

const token = new Token<string>("Factory token");

container.register({ token, factory: (container) => "Value" });

const value = container.inject(token);

console.log(value); // Value

Factory function can also take additional arguments:

const token = new Token<string>("Factory token");

container.register({
  token,
  factory: (container, a: string, b): string => a + b,
});

const value = container.inject(token, "Hello, ", "world!");

console.log(value); // Hello, world!

As a usual function, a factory can contain any additional logic, conditions, or dependencies.

Child containers

You can create child containers to isolate the scope of the classes. Child

Dioma

Install / Use

README