Node.js · Chapter 6 of 43
npm & package.json
npm (Node Package Manager) is the tool used to install, manage and share JavaScript packages. Every Node.js project usually has a `package.json` file describing it.
package.json lists your project's dependencies, scripts, version, and metadata, making projects reproducible on any machine.
Creating package.json
Run `npm init -y` to quickly generate a default package.json file for your project.
Installing packages
Use `npm install <package>` to add a dependency; it gets recorded in package.json and installed into node_modules.
Example 1 (javascript)
npm init -y
npm install expressOutput
{
"name": "my-app",
"dependencies": { "express": "^4.18.2" }
}npm init creates the file; installing express adds it as a dependency.
Example 2 (javascript)
// package.json scripts
"scripts": {
"start": "node app.js"
}
// then run:
// npm startThe scripts section lets you define shortcuts like `npm start` or `npm test`.
Key points
- package.json describes a Node.js project.
- npm install adds dependencies and updates package.json.
- node_modules stores installed packages.
- The scripts field defines custom CLI commands.
💡 Note: Never edit node_modules by hand — it's regenerated from package.json and package-lock.json.