IoC/DI container for TypeScript

Minimalistic IoC/DI container for TypeScript without dependencies which does exactly what it should and not more. Proof of concept that IoC/DI container implementation can be that simple.

Out-of-the-box it can only provide you with singleton or everytime-new instances of any class. In case you need something more complex you can register a custom resolver.

Doesn't support primitive values. Because it shouldn't.

Doesn't support TypeScript interface and type. Actually there are no libraries supporting them since types and interfaces are ephemeral build time entities and they just don't exist in runtime.

Integrates smoothly to Vue.js 2/3 projects with vue-class-component or composition API.

How to use

npm i mini-ioc

If you want to resolve classes automatically:

Install reflect-metadata to be able to pass type information about constructor arguments and properties to runtime
Add import 'reflect-metadata' to the entry point of your application to make TypeScript provide decorated entities with reflection metadata
Configure TypeScript to support decorators and runtime type metadata with flags compilerOptions.experimentalDecorators = true and compilerOptions.emitDecoratorMetadata = true respectively in your tsconfig.json

Then you can use an IOC container like this:

import Container, { Resolvable } from "mini-ioc";

// Any class you are going to resolve with container should decorated with Resolvable
@Resolvable
class SomeClass {}

@Resolvable
class SomeOtherClass {
	public constructor(
		// Constructor arguments will be resolved by a container
		public someInstance: SomeClass
	);
}

// Container instance
const container = new Container();

// Resolve class as a single instance every time (like singleton)
const single = container.get(SomeOtherClass);
console.log(single === container.get(SomeOtherClass)); // true

// Resolve a fresh class instance
const newInstance = container.create(SomeOtherClass);
console.log(single === newInstance); // false

// Constructor arguments are resolved automatically as single instances with container.get
console.log(single.someInstance === newInstance.someInstance); // true

You can provide any subclass to create a class instance from.

import Container, { Resolvable } from "mini-ioc";

abstract class BaseClass {}
@Resolvable
class SubClass extends BaseClass {}

const container = new Container();

// Bind abstract class implementation
container.bind(BaseClass, SubClass);

console.log(container.get(BaseClass) instanceof SubClass); // true

You can completely override default behavior for a class instance creation.

import Container from "mini-ioc";

abstract class BaseClass {}
// Mind that you don't need Resolvable decorator for custom resolvers.
// Helpful for third-party libraries.
class SubClass extends BaseClass {
	protected field!: string;

	public static function makeInstance() {
		const instance = new SubClass();
		instance.field = "Hello there";
		return instance;
	}
}

const container = new Container();

// Register custom function as a resolver for BaseClass
container.registerResolver(BaseClass, (classCtor, container) => classCtor.makeInstance());

console.log(container.get(BaseClass) instanceof SubClass); // true

And that's all.

Vue.js support

npm i mini-ioc mini-ioc-vue

To make things work in Vue.js components you should register mini-ioc container in app root provide:

import { provideContainer } from "mini-ioc-vue";

const rootOptions = {
	provide: {
		...provideContainer((container) => {
			// do with the container whatever you need to initialize your dependencies
		}),
		// ...mapProvider() // if you don't need configuration
	},
};

// for Vue 2
import Vue from "vue";

const app = new Vue(rootOptions);

// for Vue 3
import { createApp } from "vue";

const app = createApp(rootOptions);

Vue 3 options API (Vue 2 support is limited)

Resolving will work for both Vue 2 and 3, but typing will be available only for Vue 3 with defineComponent.

import { defineComponent } from "vue";
import { injectContainer, computedResolver } from "mini-ioc-vue";
import SomeClass from "./anywhere";

defineComponent({
	inject: {
		...injectContainer(),
	},
	computed: {
		// resolve as a singleton (container.get)
		someInstance: computedResolver(SomeClass),
		// resolve as an everytime-new instance (container.create)
		freshSomeInstance: computedResolver(SomeClass, true),
	},
});

Vue 3 composition API (Vue 2 + @vue/composition-api)

import { defineComponent, inject } from "vue";
import { injectKey } from "mini-ioc-vue";
import SomeClass from "./anywhere";

defineComponent({
	setup() {
		const container = inject(injectKey);
		const someInstance = container.get(SomeClass);
		const freshSomeInstance = container.create(SomeClass);
	},
});

Vue 2/3 + vue-class-component

npm i mini-ioc mini-ioc-vue mini-ioc-vue-class

Decorators are using computedResolver under-the-hood so the result is the same as using options API. But with decorators you get typing support for both Vue 2 and 3.