Manual Invocation

controller.js

let db = require('db_module'),
config = require('config');

let DB = new db(config.db);

// Now you can use DB

export default class Controller{
  postIndex(req, res){
    DB.insert('table', req.get('data'));
  }
}

db_module.js

//example of a module that needs "something" to be given for its usage
export default class DB{
  constructor(config){
    this.config = config;
  }
  select(){
    // select code
  }
  insert(){
    // insert
  }
  // etc
}