Simple nodejs http proxy, works with https and http forwarding

proxy.js

const http = require("http");
const https = require("https");

// Ignore SSL error
process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";

const createProxyServer = ({ url, headers, responseHeaders } = {}) => {
  let forwardUrl;
  try {
    forwardUrl = new URL(url);
    console.log("Setting up proxy for:", url);
  } catch (e) {
    console.log("Invalid url:", url);
    throw e;
  }

  return http.createServer((req, res) => {
    const requestUrl = new URL(req.url, `http://${req.headers.host}`);
    const options = {
      hostname: forwardUrl.hostname,
      port: forwardUrl.protocol === "https:" ? 443 : 80,
      path: requestUrl.pathname + requestUrl.search,
      method: req.method,
      headers: {
        ...req.headers,
        ...headers,
      },
    };

    const proxyServer = options.port === 443 ? https : http;
    const proxyReq = proxyServer.request(options, (proxyRes) => {
      const proxyResHeaders = { ...proxyRes.headers };
      if (responseHeaders["access-control-allow-origin"]) {
        delete proxyResHeaders["access-control-allow-origin"];

        // if not set then Origin can add this and duplicate value will be
        // served as we overwrite below
        res.setHeader(
          "Access-Control-Allow-Origin",
          responseHeaders["access-control-allow-origin"]
        );
      }

      const proxyResponseHeaders = {
        ...proxyRes.headers,
        ...responseHeaders,
      };

      res.writeHead(proxyRes.statusCode, proxyResponseHeaders);
      proxyRes.pipe(res, { end: true });
    });

    proxyReq.on("error", (err) => {
      console.error("Proxy Request Error:", err);
      res.statusCode = 500;
      res.end("Proxy Request Error");
    });

    // Forwarding request body if exists
    if (req.method !== "GET" && req.method !== "HEAD") {
      req.pipe(proxyReq, { end: true });
    } else {
      proxyReq.end();
    }
  });
};

const server = createProxyServer({
  url: "https://api.example.com",
  // custom header if you want to pass
  headers: {
    Origin: "http://localhost:3000",
  },
  // custom response header if you want in return
  responseHeaders: {},
});

const PORT = process.env.PROXY_PORT || 4444;

server.listen(PORT, () => {
  console.log(`Proxy server is running on port ${PORT}`);
});