Types of Modules in Node.js

Node.js provides different types of modules to organize and reuse code effectively.

The main types are Local Modules, Core Modules, and Third-Party Modules.

Local modules are modules that you create yourself and use in your application.

A good example is a module library.js that can be imported in main.js.

const greet = require('./library.js');

console.log(greet("Rajesh"));

To import a local module, use the require() function with the path to your module:

• require('./filename')
• require('./filename.js')
• require('./path/filename.js')

const moduleName = require("./filename.js");
const moduleName2 = require("./filename");

Core modules come with Node.js by default. You do not need to download them.

Popular core modules include fs (File System), os (Operating System), path, etc.

const fs = require("fs");
const os = require("os");

Global core modules like console do not require importing.

Non-global core modules like fs must be imported before use.

Third-party modules are downloaded via a package manager like npm.

They are usually stored in the node_modules folder and can be installed locally or globally.

Examples include express, mongoose, react, etc.

To install a third-party module:

• Locally: npm i module_name
• Globally: npm i module_name -g

To import a third-party module, use require() with the module name:

const express = require("express");
const mongoose = require("mongoose");