index.js

'use strict'

const { resolve, extname } = require('path')
const http = require('http')
const fs = require('fs')

const PORT = process.env.PORT || 8080
const PUBLIC_PATH = 'public/' // place it directory, where you execute node

const MIME_TYPES = {
  'css': 'text/css',
  'html': 'text/html'
}

http.createServer((req, res) => {
  const url = req.url === '/' ? 'index.html' : req.url.slice(1)
  const path = resolve(PUBLIC_PATH, url) // style.css
  console.log(path)
  const ext = extname(path).slice(1) // .css
  const mimeType = MIME_TYPES[ext]
    ? MIME_TYPES[ext]
    : 'text/plain'
  
  fs.readFile(path, (err, data) => {
    if (err) {
      res.writeHead(400, { 'content-type': 'text/plain' }).end('No such file')
    } else {
      res.writeHead(200, { 'content-type': mimeType }).end(data)
    }
  })
}).listen(PORT)