Quartz 4

Package Management

2 min read

Package management is where Node.js projects really come alive 🚀. Let’s go through it step by step.

📦 1. Package Managers (NPM & Yarn)

NPM (Node Package Manager)

  • Default package manager that comes with Node.js.

  • Lets you:

    • Install packages (npm install express)

    • Manage dependencies in package.json

    • Run scripts (npm run start)

Yarn

  • Alternative to npm (created by Facebook).

  • Focused on speed, deterministic installs, and workspaces.

  • Syntax is very similar:

    • yarn add express = npm install express

    • yarn start = npm run start

🔑 Nowadays, both npm (v7+) and Yarn are fast and reliable. Many teams pick one and stick to it.

📂 2. package.json

The manifest file for every Node project.
It describes your project and its dependencies.

Example:

{
  "name": "my-app",
  "version": "1.0.0",
  "description": "A simple Node.js app",
  "main": "index.js",
  "scripts": {
    "start": "node index.js",
    "dev": "nodemon index.js",
    "test": "jest"
  },
  "dependencies": {
    "express": "^4.18.2"
  },
  "devDependencies": {
    "nodemon": "^3.0.0"
  }
}

Key sections:

  • "name", "version" → metadata.

  • "main" → entry point of your app.

  • "dependencies" → packages needed at runtime.

  • "devDependencies" → packages only for development (e.g., testing tools).

  • "scripts" → custom commands.

⚙️ 3. Scripts

Defined in package.json under "scripts".

Run them with:

npm run <script-name>
# or
yarn <script-name>

Example:

"scripts": {
  "start": "node index.js",
  "dev": "nodemon index.js",
  "test": "jest",
  "lint": "eslint ."
}

Usage:

npm run dev
# Runs "nodemon index.js"

Special cases:

  • "start" and "test" can be run without run:

    npm start
npm test

🧩 4. Lock Files

  • package-lock.json (npm) or yarn.lock (Yarn).

  • Ensures consistent dependency versions across machines.

  • Should always be committed to version control.

✅ In Short

  • NPM is the default package manager; Yarn is an alternative with similar commands.

  • package.json defines your app’s metadata, dependencies, and scripts.

  • Scripts let you automate tasks (start, test, lint, build, etc.).

  • Lock files ensure reproducible installs.

👉 Do you want me to go deeper into how dependencies are resolved (semver ^, ~, exact versions) and how node_modules works internally, or should we move to the next core Node.js concept like Non-blocking I/O?

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