Dolza

Dolza is a lightweight dependency injection container for JavaScript and Node.js, based on Chapter 5 of Node.js Design Patterns by Mario Casciaro (ISBN 9781783287314).

TODO

1. Add remain (pre)production tests
2. Complete pending regular tests
3. Add type definitions with JSDoc or TypeScript, so it looks pretty in WebStorm for me

Basic Usage

First, create some factories:

let f1 = () => {
	let product = Object.create( null );

	// Define some methods for `product`

	return product;
}

let f2 = ( fac ) => {
	let product = Object.create( null );

	// Define some methods for `product` using `fac`

	return product;
}

Register the factories with Dolza:

let dolza = require( 'dolza' );
dolza.register( 'f1', f1 );             // no dependencies
dolza.register( 'f2', f2, [ 'f1' ] );    // f2 depends on f1

Then ask Dolza for what you need. It will instantiate dependencies as needed and return the product of the factory.

let f2product = dolza.get( 'f2' );

Dolza can also store things that aren't factories. Just use store instead of register.

dolza.store( 'a1', [ 0, 1, 2, 3, 4 ] );
dolza.store( 'o2', { name: 'Weaver', rank: 'Colonel' } );
let myArray = dolza.get( 'a1' );
let fighter = dolza.get( 'o1' );

Key usage points:

• The third argument to register (which is optional) MUST be an array, even if it only has one element.
• Dependencies are passed to the factory in the same order that they appear in the array.
• Dependencies aren't limited to factories. Data that passed to store can also be used as a dependency.
• The order in which factories are registered doesn't matter, as long as everything is in the container before get is called.

Installation

Dolza is written in ES6 and uses spread operators. To use with Node.js ( > 5.x), you'll to run your app with the --es_staging flag, e.g., node --es_staging index.js.

Use in a browser probably requires transpiling or something. I haven't tried it yet.

Yet Another DI Framework?

NPM is lousy with DI frameworks, some of which cause me a great deal of confusion and befuddlement. I wanted something lightweight and easy (for me) to grok. I also wanted a container that didn't require any changes to factories or modules and that would play well with minification.

Building a DI container also looked like a fun and interesting challenge. And it was!