Node.js npm (Node Package Manager)

npm (Node Package Manager) is a powerful tool bundled with Node.js, used for managing packages, dependencies, and scripts for your Node.js applications. It simplifies the process of sharing and using reusable code in your projects.

 

Key Features of npm

1. Package Management: Install, update, and remove libraries.
2. Dependency Management: Maintain a package.json file for project dependencies.
3. Script Runner: Automate tasks using npm scripts.
4. Custom Package Creation: Publish your own libraries to the npm registry.

 

Using npm

1. Verify npm Installation

• npm is installed automatically with Node.js.
• Check the version:

npm -v

Output (Example):

9.5.1

2. Initialize a Node.js Project

• Create a package.json file to manage dependencies:

npm init -y

Output:

• A package.json file with default settings.

3. Install a Package

• Install a package locally (available only in the project directory):

npm install lodash

Output: A node_modules folder is created, containing the lodash library.

• To install a package globally (available system-wide):

npm install -g nodemon

 

4. Use Installed Packages

• Import and use the lodash library in your project:

const _ = require('lodash');

const numbers = [1, 2, 3, 4];
console.log(_.reverse(numbers)); // Output: [4, 3, 2, 1]

5. Install Specific Versions

• Install a specific version of a package:

npm install [email protected]

• Update a package to the latest version:

npm update express

6. Uninstall a Package

• Remove a locally installed package:

npm uninstall lodash

• Remove a globally installed package:

npm uninstall -g nodemon

7. npm Scripts

• Automate tasks by defining scripts in package.json:

{
  "scripts": {
    "start": "node app.js",
    "test": "echo 'Running tests'"
  }
}

• Run the script:

npm run start
npm run test

8. Publishing a Package

• Create an account at npm Registry.
• Login via terminal:

npm login

• Publish your package:

npm publish

 

Summary

npm is an essential tool for managing Node.js projects. It allows you to install libraries, handle dependencies, automate tasks, and even publish your own packages. Understanding npm enhances your productivity and simplifies application development.