How To Use Node Modules with npm and package.json

Last Updated : 12 Mar, 2024

NodeJS is a powerful runtime for server-side JavaScript & these modules are reusable pieces of code that can be easily imported and used in NodeJS applications. npm (Node Package Manager) is the default package manager for Node JS and is used to install, manage, and publish NodeJS packages. This article will guide you through the process of using NodeJS modules with npm and package.json, covering various approaches, and steps to create an application, updating dependencies in package.json, and providing examples with outputs.

Table of Content

Key Features:

Comprehensive coverage of using NodeJS modules with npm.
Clear explanations and examples for easy understanding.
Practical steps to create an application and manage dependencies.
Visual aids such as GIFs or screenshots for better illustration.
References for additional reading and learning.

1. Initialize a Node.js project:

If you haven't already, you need to initialize your NodeJS project. Open a terminal or command prompt, navigate to your project directory, and run:

npm init -y

This command initializes a new NodeJS project with default settings and creates a package.json file.

2. Install Node.js modules:

To install Node.js modules (packages) using npm, run:

npm install <package-name>

Replace <package-name> with the name of the package you want to install. For example:

npm install express

This will install the Express framework package.

You can also install multiple packages at once by separating them with spaces:

npm install express mongoose body-parser

3. Save dependencies to `package.json`:

When you install packages using npm, you can choose to save them as dependencies in your package.json file. There are two types of dependencies: dependencies (packages required for your application to run) and devDependencies (packages required for development purposes only, such as testing frameworks or build tools).

To save a package as a dependency:

npm install <package-name> --save

To save a package as a devDependency:

npm install <package-name> --save-dev

For example:

npm install jest --save-dev

4. Use installed modules in your code:

Once you've installed the desired modules, you can use them in your Node.js code. For example, if you've installed Express, you can create an Express server like this:

const express = require('express');
const app = express();

app.get('/', (req, res) => {
  res.send('Hello, world!');
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

5. Include `package.json` in your project:

Ensure that your package.json file is included in your project directory. This file contains metadata about your project and lists its dependencies.

6. Install dependencies from `package.json`:

If you're sharing your project with others or deploying it to a server, you can install all the dependencies listed in your package.json file by running:

npm install

This command will install all dependencies (both regular and devDependencies) listed in your package.json file.

That's it! You've now successfully used NodeJS modules with npm and package.json. You can continue adding more dependencies as needed and managing them through your package.json file.