JSDI

JavaScript Dependency-Injection

If you are not familiar with dependency injection, we recommend you read up on it. We have a small document explaining the basics of DI, but you'd probably be better off learning it from a legitimate learning resource rather than reading our quick summary.

But why

ES6 introduced import and export, so Javascript doesn't actually need dependency injection, but it's a good pattern to learn and use. It makes code more testable because you don't have to magically mock import statements, you just pass in mocked objects.

We are not saying you should use DI for javascript, just that it's possible. In some cases it's very valuable. You probably don't need to use it for your website or web application, but take for instance a HTML5 game. Using DI, you can easily swap out parts of your game and manage global config easily in a way that's incredibly flexible.

Why you probably shouldn't use this

• This is experimental and hasn't been extensively tested in the wild.
• The feature set of this library is incomplete.
• There is currently only one author which may slow down responses to issues and pull requests.
• (This is literally my first ever npm library repo and there are likely to be teething problems at first)

We certainly wouldn't recommend this for any real projects. We're just using it for experimentation.

Usage

Add this to your package.json (I tried to publish this to NPM, but I had trouble. I'm looking into making this a legit npm module asap):

  "dependencies": {

    "jsdi": "github:alexmorleyfinch/jsdi#1.0.0"

  },

You can use JSDI with only 3 functions. container, make and ref. Click here to see the API.

• container is used to wrap the object.
• make is used to instantiate classes.
• ref is used to reference parts of the object.

Create a file like this describing your app (you can create multiple of these for multiple environments):

// src/builds/build-number-1.js

import {container, make, ref} from 'jsdi';
import MyClass from './MyClass';
import MyFactory from './MyFactory';

export default container({
  config: {
    ENV: '<some environment>'
    SOME_SECRET: '<secret>',
  },

  myClass: make(MyClass, [
    ref('config.SOME_SECRET')
    {
      some: {
        additional: 'config',
        specific: ['to', 'this', 'class']
      }
    }
  ]),

  myFactory: make(MyFactory, [
    ref('config.SOME_SECRET'),
    ref('myClass'),
  ])
})

Then use it where ever you need to bootstrap the app:

// import build number 1
import MyApp from 'src/builds/build-number-1';

// bootstrap application
const root = document.getElementById('root');
MyApp.myClass.initialise(root);

Click here for a real world example

Contributing

If you want to contribute and improve this library, great! Click here to see a helpful contribution guide