Node.js Introduction

// console.log works same
console.log("Hello from Node.js!");

// Built-in modules
const os = require("os");
const path = require("path");

console.log("OS:", os.type());
console.log("Platform:", os.platform());
console.log("CPU cores:", os.cpus().length);
console.log("Free memory:", (os.freemem() / 1024 / 1024).toFixed(2), "MB");
console.log("Home dir:", os.homedir());

// path module
const filePath = path.join(__dirname, "data", "users.json");
console.log("File path:", filePath);
console.log("Extension:", path.extname("app.js")); // .js
console.log("Basename:", path.basename("/home/user/app.js")); // app.js

// Run: node app.js

# npm basics
npm init -y           # package.json create karo
npm install express   # package install
npm install -D jest   # dev dependency
npm uninstall express # uninstall
npm update            # update packages

# package.json scripts
# "scripts": {
#   "start": "node app.js",
#   "dev": "nodemon app.js",
#   "test": "jest"
# }

npm run dev   # dev script run karo
npm start     # start script run karo
npm test      # test script run karo