Day 3 of NodeJS||Important Modules

This content originally appeared on DEV Community and was authored by Akshat Sharma

Hey readerHope you are doing well
In the last post we have discussed about how to get started with NodeJS. In this post we are going to see Modules in NodeJS.
So let’s get started

What are Modules?

Consider modules as JavaScript libraries that provides different functionalities for development. Modules can be a single file or a collection of multiple files/folders. The reason programmers are heavily reliant on modules is because of their reusability as well as the ability to break down a complex piece of code into manageable chunks.
Node.js treats each file in a Node project as a module that can export values and functions from the file.

Here utility.js is a module but it is not exporting anything right now.

exports in NodeJS -:
We can export functions and properties either by using module.exports or exports. The exports keyword is a reference to the exports object in the modules object.

Different types of NodeJS Modules

There are three types of modules-:

• Core Modules

• Local Modules

• Third Party Modules

Core Modules

Node.js has many built-in modules that are part of the platform and come with Node.js installation. These modules can be loaded into the program by using the required function.
const module=require(module_name)
The require() function will return a JavaScript type depending on what the particular module returns.
Some of the Core modules are -:

• http -: creates an HTTP server in Node.js.

• https -: creates an HTTPs server in Node.js.

• fs -: used to handle file system.

• path -: includes methods to deal with file paths.

• os -: provides information about the operating system.

• process -: provides information and control about the current Node.js process.

• querystring -: utility used for parsing and formatting URL query strings.

• url -: module provides utilities for URL resolution and parsing.

• assert -: set of assertion functions useful for testing.

• tls -: to implement TLS and SSL protocols.

• net -: to create servers and clients.

• crypto -: to handle OpenSSL cryptographic functions.
  These are some of the important built-in modules.

Local Modules

We can create our own module too apart from built-in and third party modules.
Let’s create a simple calculation module-:

• Step1 -> Create Calculation.js file-:
  
  Let me show you module object here-:
  
  You can see that we are exporting four functionalities here.

• Step 2 -> Use the module in script.js file -:
  
  Here we have imported the module using require keyword.

• Output ->
  
  Easy huh

Third-party modules

Third-party modules are modules that are available online using the Node Package Manager(NPM). These modules can be installed in the project folder or globally. Some of the popular third-party modules are Mongoose, express, angular, and React.
Example -:

• npm install express
• npm install mongoose
• npm install -g @angular/cli

So this was all about modules. I hope you have understood this blog. In the next blog we will see one another way of using module in a file. Till then stay connected and don’t forget to follow me.
Thankyou

This content originally appeared on DEV Community and was authored by Akshat Sharma