preview-server.js

const http = require('http');
const fs = require('fs');
const path = require('path');

const root = __dirname;
const mime = {
  '.html': 'text/html; charset=utf-8',
  '.css': 'text/css; charset=utf-8',
  '.js': 'text/javascript; charset=utf-8',
  '.png': 'image/png',
  '.svg': 'image/svg+xml'
};

const server = http.createServer((req, res) => {
  const urlPath = decodeURIComponent(req.url.split('?')[0]);
  const file = urlPath.startsWith('/node_modules/')
    ? path.join(root, urlPath.slice(1))
    : path.join(root, 'src', 'renderer', urlPath === '/' ? 'index.html' : urlPath.replace(/^\//, ''));

  if (!file.startsWith(root)) {
    res.writeHead(403);
    res.end('Forbidden');
    return;
  }

  fs.readFile(file, (error, data) => {
    if (error) {
      res.writeHead(404);
      res.end('Not found');
      return;
    }

    res.writeHead(200, { 'Content-Type': mime[path.extname(file)] || 'application/octet-stream' });
    res.end(data);
  });
});

server.listen(4177, '127.0.0.1', () => {
  console.log('preview http://127.0.0.1:4177');
});