di-service's Introduction

DI Service

Really simple dependency injection solution for JavaScript

Features

Implements DI pattern
Do not impose any system architecture, may be introduced to any JavaScript project (FE and BE both)
Pure JavaScript implementation (+ TypeScript declaration file)
Zero dependencies
ES Module and CommonJS hybrid module

Example

Declare any class

class Settings {
    dbServer = process.ENV.DB_SERVER;
    dbUser = process.ENV.DB_USER;
    dbPassword = process.ENV.DB_PASSWORD; // don't do like this
}

module.exports = { Settings };

Use the class as a dependency

const { Settings } = require('./settings');
const { SERVICE_REQUIRE } = require('di-service');

class DBConnection {
    
    static [SERVICE_REQUIRE] = [Settings];
    
    constructor(settings) {        
        // settings -> instance of the Settings class
        this.settings = settings;
    }
}

module.exports = { DBConnection };

Get service instance

const { DIService } = require('di-service');
const { DBConnection } = require('./db-connection');

const services = new DIService();
const connection1 = await services.getInstance(DBConnection);
const connection2 = await services.getInstance(DBConnection);
console.log(connection1 === connection2); // -> true
console.log(connection1.settings === connection2.settings); // -> true
console.log(connection1.settings.constructor.name); // -> Settings