javascript-dependency-injection

Javascript Dependency Injection library (ES2015)

DI makes classes accessible by a contract. Instances are created when requested and dependencies are injected into the constructor, facilitating lazy initialization and loose coupling between classes.

As an example, consider a User and Persitance classes:

 class FileDB {
     constructor(fs, tableName, listOfFields) { .... }
     
     persist(record) { .... }
 }
 
 class User {
     constructor(email, passwd, storage, role) { ... }
     
     save() { this.storage.persist(this); }
 }

To define the relation between both classes use DI#register

import fs from 'fs';

var di = new DI();

di.register('$user', User, [null, 'welcome', '$fileDb', 'nobody']);
di.register('$fileDb', FileDb, [fs, 'user', ['email','passwd', 'role']], {singleton: true});

The 1st argument of DI#register is the name of the contract, the 2nd the class reference, the 3rd an array of the constructor arguments and the last a config object. Currently ther config has only 2 options

- singleton, it only create the instance once
- notAClass, meaning that the reference is not a class

To get instances do

di.getInstance('$user', '[e-mail]');

or if you also wish to change the role

di.getInstance('$user', '[e-mail]', null, null, 'admin');

For more advanced use-cases checkout the unit tests file.

You can find a detailed API description + a code-coverage report here

Installation

Install the dependencies as follows

$> npm install --save javascript-dependency-injection@beta

Unit testing

Unit testing is can be done as follows

$> npm test

it will also open the code-coverage report

Documentation

$> npm run doc