serve.js

import http from 'node:http';
import { readFile } from 'node:fs/promises';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const root = path.dirname(fileURLToPath(import.meta.url));
const port = Number(process.argv[2]) || Number(process.env.PORT) || 4175;

const types = {
  '.html': 'text/html; charset=utf-8',
  '.css': 'text/css; charset=utf-8',
  '.js': 'text/javascript; charset=utf-8',
  '.json': 'application/json; charset=utf-8',
  '.svg': 'image/svg+xml',
  '.ico': 'image/x-icon',
  '.png': 'image/png',
  '.webp': 'image/webp',
  '.txt': 'text/plain; charset=utf-8',
};

const server = http.createServer(async (req, res) => {
  const url = new URL(req.url, `http://localhost:${port}`);
  let rel = decodeURIComponent(url.pathname);
  if (rel.endsWith('/')) rel += 'index.html';

  const filePath = path.join(root, rel);
  // Keep requests inside the project directory.
  if (!filePath.startsWith(root)) {
    res.writeHead(403).end('Forbidden');
    return;
  }

  try {
    const body = await readFile(filePath);
    res.writeHead(200, {
      'content-type': types[path.extname(filePath)] ?? 'application/octet-stream',
      'cache-control': 'no-store',
    });
    res.end(body);
  } catch {
    res.writeHead(404, { 'content-type': 'text/plain; charset=utf-8' });
    res.end('Not found');
  }
});

server.listen(port, () => {
  console.log(`Downforce running at http://localhost:${port}`);
});