tl;dr

• Create a module file using module.exports
• Include that module file using require(). Provide full file path. var fs = require("fs")
• OR import the ES6 way import fs from 'fs'
• You can further organize the modules by giving them their own folder. For example, people use lib to keep their modules in.

Any code that is well designed, reusable, it is a function that can process independantly, you should give it it’s own file and include that as a module. Module here just means that it is kinda bundled separately (in a different file).

create

You separate your code that you want to modularize, and make it a module using module’s export funcion.

module.exports = function() {
  // code goes here
};

include

To include a module, you again use require(), but provide a full path to the file. By default, require() looks in the node_modules folder. You can change that to look into other folders. You don’t need to put .js in the end, Node knows. For example:

var powerUp = require("./powerUp");

will look in the root folder for the file powerUp.js and include it in your project.

organize

You can create a folder to keep all your custom modules in for better organization. People tend to call that folder lib. It’s kinda like the inc folder. Your require path will change accordingly,

var powerUp = require("./lib/powerUp");