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injection-js

Build Status

Dependency Injection

Dependency injection library for JavaScript and TypeScript in 5.2K. It is an extraction of the Angular's dependency injection which means that it's feature complete, fast, reliable and well tested.

Up-to-date with Angular 4.1.

Why not Angular version 5 and above?

Angular version 5 deprecated the ReflectiveInjector API and introduced StaticInjector. In short, the dependency injection in the newest versions of Angular will happen entirely compile-time so reflection will not be necessary.

However, if you want to use dependency injection in your Node.js, Vue, React, Vanilla JS, TypeScript, etc. application you won't be able to take advantage of StaticInjector the way that Angular will because your application won't be compatible with Angular compiler.

This means that if you need dependency injection outside of Angular @angular/core is not an option. In such case, use injection-js for fast, small, reliable, high-quality, well designed and well tested solution.

How to use?

$ npm i injection-js --save

Note that for ES5 Class syntax and TypeScript you need a polyfill for the Reflect API. You can use, for instance, reflect-metadata, or core-js (core-js/es7/reflect).

TypeScript

import 'reflect-metadata';
import { ReflectiveInjector, Injectable, Injector } from 'injection-js';
 
class Http {}
 
@Injectable()
class Service {
  constructor(private http: Http) {}
}
 
@Injectable()
class Service2 {
  constructor(private injector: Injector) {}
  
  getService(): void {
    console.log(this.injector.get(Service) instanceof Service);
  }
  
  createChildInjector(): void {
    const childInjector = ReflectiveInjector.resolveAndCreate([
      Service
    ], this.injector);
  }
}
 
const injector = ReflectiveInjector.resolveAndCreate([
  Service,
  Http
]);
 
console.log(injector.get(Service) instanceof Service);

Note: you will need to enable the TypeScript flags experimentalDecorators and emitDecoratorMetadata to make this work.

ES6

const { Inject, ReflectiveInjector } = require('injection-js');
 
class Http {}
 
class Service {
  static get parameters() {
    return [new Inject(Http)];
  }
 
  constructor(http) {
    this.http = http;
  }
}
 
const injector = ReflectiveInjector.resolveAndCreate([Http, Service]);
 
console.log(injector.get(Service) instanceof Service);

ES5

require('reflect-metadata');
var di = require('injection-js');
 
var Http = di.Class({
  constructor: function () {}
});
 
var Service = di.Class({
  constructor: [Http, function (http) {
    this.http = http;
  }]
});
 
var injector = di.ReflectiveInjector.resolveAndCreate([Http, Service]);
 
console.log(injector.get(Service) instanceof Service);

For full documentation click here, here and here.

License

MIT