node --version
npm --version
npm init -y

// server.js
const http = require('http');

const server = http.createServer((req, res) => {
	res.writeHead(200, { 'Content-Type': 'text/plain' });
	res.end('Hello, Node.js!');
});

const PORT = 3000;
server.listen(PORT, () => {
	console.log(`Server running at http://localhost:${PORT}`);
});

npm install express

// app.js
const express = require('express');
const app = express();

app.get('/', (req, res) => {
	res.send('Hello from Express!');
});

app.listen(3000, () => {
	console.log('Express server running on http://localhost:3000');
});

const fs = require('fs');

// Write to a file
fs.writeFileSync('hello.txt', 'Hello, file!');

// Read from a file
const content = fs.readFileSync('hello.txt', 'utf8');
console.log(content);

export MY_SECRET=12345 # On Windows use: set MY_SECRET=12345

console.log(process.env.MY_SECRET);

// Callback
fs.readFile('hello.txt', 'utf8', (err, data) => {
	if (err) throw err;
	console.log(data);
});

// Promise
const fsPromises = require('fs').promises;
fsPromises.readFile('hello.txt', 'utf8')
	.then(data => console.log(data));

// Async/Await
async function readFile() {
	const data = await fsPromises.readFile('hello.txt', 'utf8');
	console.log(data);
}
readFile();