What is NPM?

NPM stands for Node Package Manager. It serves as a free package registry accessible to anyone, making it easier to share javascript packages with others. Users usually interact with NPM in two ways: as someone downloading a package and someone publishing a JavaScript package.

Sources

W3Schools

Understanding Node.js Modules

What is a module?

A module is basically a JavaScript library which would contain a set of functions that you want to include in your code.

Node.js has many built-in modules that you can simply use without installing anything. A list of modules can be found here.

Including modules in your own code

To use a module in your code, use the function require().

var http = require('http')

The require() function reads a JavaScript file, executes it, and then returns the exports object. The exports keyword makes properties and methods available outside of the module file.

Example

Create a module that returns the current date and time.

exports.myDateTime = function () {
  return Date();
};

Use this module in a Node.js file

var dt = require('./myfirstmodule');

We use the ./ here to locate the module because the module is located in the same file as the Node.js file.

Sources

W3Schools

NodeJS

Creating index.js and package.json

Publishing and Installing