npm (Node Package Manager) is JavaScript's default package manager for installing, updating, and managing dependencies. Key files are package.json (project metadata) and package-lock.json (exact versions). Use npm install, npm update, and npm uninstall for management.
npm Basics:
Key Files:
package.json: Project metadata, dependencies, scriptspackage-lock.json: Exact versions for reproducible installsnode_modules/: Installed packagesCommon Commands:
npm init: Create package.jsonnpm install: Install all dependenciesnpm install <pkg>: Add dependencynpm install -D <pkg>: Add dev dependencynpm update: Update packagesnpm run <script>: Run script# Initialize new project
npm init -y
# Install all dependencies from package.json
npm install
# or shorter
npm i
# Install specific package
npm install lodash
npm i lodash
# Install as dev dependency
npm install --save-dev jest
npm i -D jest
# Install specific version
npm install react@18.2.0
# Install globally
npm install -g typescript
# Update packages
npm update # Update all
npm update lodash # Update specific
# Remove package
npm uninstall lodash
# List installed packages
npm list # All
npm list --depth=0 # Only direct deps
# Check for outdated
npm outdated
# Run scripts
npm run build
npm run test
npm start # Shorthand for npm run start