3-server.js

'use strict';

const fs = require('node:fs');
const http = require('node:http');

const cache = new Map();

const cacheFile = (path) => {
  fs.readFile(path, 'utf8', (err, data) => {
    if (err) {
      cache.delete(path);
      return;
    }
    cache.set(path, data);
  });
};

const cacheFolder = (path) => {
  fs.readdir(path, (err, files) => {
    if (err) return;
    files.forEach(cacheFile);
  });
};

const watch = (path) => {
  fs.watch(path, (event, file) => {
    cacheFile(file);
  });
};

const path = './';
cacheFolder(path);
watch(path);

http.createServer((req, res) => {
  const url = req.url.substring(1);
  console.log(url);
  const data = cache.get(url);
  if (data) res.end(data);
  else res.end('File ' + url + 'not found');
}).listen(8000);

// See https://github.com/HowProgrammingWorks/LiveReload