// CommonJS
const fs = require('fs');
const path = require('path');

// ES Modules
import fs from 'fs';
import path from 'path';

const fs = require('fs');

fs.readFile('file.txt', 'utf8', (err, data) => { /* ... */ });
fs.writeFile('file.txt', 'Hello', err => { /* ... */ });
fs.appendFile('file.txt', 'World', err => { /* ... */ });
fs.unlink('file.txt', err => { /* ... */ });

const http = require('http');
const server = http.createServer((req, res) => {
  res.end('Hello Node');
});
server.listen(3000);

const express = require('express');
const app = express();

app.get('/', (req, res) => res.send('Home'));
app.post('/data', (req, res) => res.json({ ok: true }));

app.listen(3000);

// .env
PORT=3000

// app.js
require('dotenv').config();
console.log(process.env.PORT);

const path = require('path');
const os = require('os');

console.log(path.join(__dirname, 'file.txt'));
console.log(os.platform(), os.cpus());

process.argv        // Command line args
process.env         // Env variables
process.exit(0)     // Exit process

const EventEmitter = require('events');
const emitter = new EventEmitter();
emitter.on('event', () => {});
emitter.emit('event');

console.log('Log');
setTimeout(() => {}, 1000);
setInterval(() => {}, 1000);