Node.js Core Modules

const fs = require('fs'); # import fs module
fs.readFile('file.txt', 'utf8', (err, data) => { }); # async read
const data = fs.readFileSync('file.txt', 'utf8'); # sync read
fs.writeFile('file.txt', 'data', err => { }); # write file

const path = require('path');
path.join('dir', 'file.txt'); # join paths
path.basename('/path/to/file.txt'); # file.txt
path.dirname('/path/to/file.txt'); # /path/to
path.extname('file.txt'); # .txt

const http = require('http');
const server = http.createServer((req, res) => {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('Hello World');
});
server.listen(3000);

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

const os = require('os');
os.platform(); # operating system
os.cpus(); # CPU info
os.freemem(); # free memory
os.homedir(); # home directory