Node.js — package.json

Basic package.json

{
  "name": "my-app",
  "version": "1.0.0",
  "description": "My application",
  "main": "index.js",
  "scripts": {
    "start": "node index.js"
  }
}

Essential Fields

Field	Description
name	Package name (lowercase, no spaces)
version	Semantic versioning (major.minor.patch)
description	Package description
main	Entry point file
scripts	Command shortcuts
author	Author information
license	License type

Dependencies

{
  "dependencies": {
    "express": "^4.18.2",
    "lodash": "~4.17.0"
  },
  "devDependencies": {
    "nodemon": "^3.0.0",
    "jest": "^29.0.0"
  }
}

Version Ranges

Symbol	Meaning
^	Compatible with version
~	Approximately version
*	Any version
1.0.0	Exact version

Scripts

{
  "scripts": {
    "start": "node index.js",
    "dev": "nodemon index.js",
    "test": "jest",
    "build": "webpack --mode production",
    "lint": "eslint ."
  }
}

Mini Practice

Create a package.json
Add dependencies
Configure scripts
Set version ranges

Up Next

Continue with File System — reading and writing files.

Frequently Asked Questions about package.json

What is package.json in Node.js?

package.json is a fundamental concept in Node.js. This lesson explains it step by step with clear examples, making it easy for beginners to understand.

How do I learn package.json?

Start by reading the explanation above, then try the code examples. Practice by modifying the examples and experimenting with different values. Hands-on practice is the best way to learn package.json.

Why is package.json important in Node.js?

package.json is essential for Node.js development. Understanding this concept will help you write better code and solve real-world problems more effectively.