npm tutorial

What is npm?

npm is software repository for JavaScript code.

npm is a command-line tool to manage JavaScript/TypeScript packages.

npm is bundled with Node.js.

2. install node.js

download at https://nodejs.org

Verify installation:

node -v

npm -v

Create project

mkdir my-t-app
cd my-t-app

# Initialize a new project (creates package.json)
npm init -y

-y means don't ask questions

package.json is the heart of every npm project. Example:

{
  "name": "my-t-app",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}

installing packages

Install dependency

npm install express
# or short form
npm i express

Local packages are installed in node_modules dir of current dir.

Save as devDependency (only for development)

npm install --save-dev nodemon typescript
# or
npm i -D nodemon typescript

Install a specific version

npm i lodash@4.17.21

Install globally (CLI tools)

npm install -g create-vite

npm global module location

# show npm global install dir
npm root -g

usually

• Windows: %AppData%/npm/node_modules (often ~/AppData/Roaming/npm/node_modules)
• macOS/Linux: /usr/local/lib/node_modules (or a user-specific path like ~/.nvm/versions/node/<version>/lib/node_modules if using nvm)

5. package.json fields you should know

6. npm scripts (most useful feature)

Edit the "scripts" section in package.json:

{
  "scripts": {
    "start": "node index.js",
    "dev": "nodemon index.js",
    "build": "tsc",
    "test": "jest",
    "lint": "eslint .",
    "format": "prettier --write \"**/*.{js,ts}\""
  }
}

Run them with:

npm start
npm run dev        # use "run" for custom scripts
npm test

7. common commands cheat sheet

# Install all dependencies in a project
npm install
# or
npm i

# Update packages
npm update

# Check for outdated packages
npm outdated

# Uninstall a package
npm uninstall express
npm rm express

# Clean install (fixes weird issues)
rm -rf node_modules package-lock.json
npm install

# View global packages
npm list -g --depth=0

8. package-lock.json vs yarn.lock / pnpm-lock.yaml

• package-lock.json is created automatically by npm
• Never delete it if you want reproducible installs
• Commit it to git

9. publishing your own package

1. Create an account: https://www.npmjs.com
2. In your project:

npm login
npm publish

Pro tips for publishing:

• Use scoped packages: @yourusername/my-lib
• Add .npmignore or use "files" field in package.json
• Use semantic versioning (major.minor.patch)

10. modern best practices (2026)

• Use npm workspaces for monorepos
• Prefer Vite + TypeScript for new projects
• Use npm ci in CI/CD (faster, stricter)
• Enable Corepack for better package manager control:

corepack enable

• Consider pnpm or Bun for faster installs in large projects (but npm is still excellent)

Bonus: quick start with vite (recommended)

npm create vite@latest my-react-app -- --template react-ts
cd my-react-app
npm install
npm run dev

You now know enough npm to build real applications!

Want a follow-up tutorial on any of these?

• npm workspaces / monorepos
• Publishing scoped packages
• Security & auditing (npm audit)
• Using .nvm or Volta
• Comparing npm vs pnpm vs Bun