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Beginner's Guide to Node.js and NPM

This guide explains how to install and manage packages in Node.js projects using npm, with practical commands you will use every day.

Prerequisites​

  • Node.js installed (npm is included)
  • VS Code installed
  • Terminal access (PowerShell, Command Prompt, Git Bash, macOS/Linux terminal)

Check your versions:

node -v
npm -v

1. Initialize a project​

Before installing packages, create a package.json file.

npm init -y

What this does:

  • Creates package.json with default values
  • Registers project metadata and dependencies

2. Install dependencies​

2.1 Runtime dependency​

Use this for libraries required in production.

npm install dayjs

Short form:

npm i dayjs

Result:

  • Adds package to dependencies in package.json
  • Creates/updates package-lock.json
  • Downloads modules into node_modules/

2.2 Development dependency​

Use this for tooling (linters, test runners, watchers, etc.).

npm install nodemon --save-dev

Short form:

npm i -D nodemon

Result:

  • Adds package to devDependencies

3. Use an installed library​

Create index.js:

const dayjs = require('dayjs');

const now = dayjs().format('YYYY-MM-DD HH:mm:ss');
console.log('Current time:', now);

Run it:

node index.js

4. Global packages​

Install globally only when you need a CLI command available system-wide.

npm install -g typescript
warning

Avoid global installs for project-specific tooling. Prefer local dev dependencies plus npx.

5. Essential npm commands​

Remove a package​

npm uninstall dayjs

Update packages (within allowed semver range)​

npm update

Install dependencies from package.json​

npm install

Use this after cloning a repository.

6. Useful VS Code workflow​

  1. Open the integrated terminal (`Ctrl + ``) in the project root.
  2. Use the NPM SCRIPTS panel to run scripts from package.json.
  3. Use IntelliSense for import/require suggestions from installed packages.

Quick reference​

GoalCommandShort form
Initialize projectnpm init -y-
Install dependencynpm install <name>npm i <name>
Install dev dependencynpm install <name> --save-devnpm i -D <name>
Install global packagenpm install -g <name>-
Remove dependencynpm uninstall <name>npm un <name>
Install from lockfile/package.jsonnpm installnpm i
Run scriptnpm run <script>-

Common mistakes​

  • Committing node_modules/ to Git.
  • Installing everything globally.
  • Forgetting to run npm install after cloning a project.
  • Editing package-lock.json manually.

Next steps​

  • Learn package.json scripts (build, dev, test).
  • Learn npx for running local binaries.
  • Add linting and formatting (eslint, prettier) as dev dependencies.
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