index.js
function performRequest (options, isFirstRequest) {
  // This should be the default export of either request or request-promise.
  const requester = options.requester;

  // Note that request is always an instanceof ReadableStream, EventEmitter
  // If the requester is request-promise, it is also thenable.
  const request = requester(options);

  // We must define the host header ourselves to preserve case and order.
  if (request.getHeader('host') === HOST) {
    request.setHeader('host', request.uri.host);
  }

  // If the requester is not request-promise, ensure we get a callback.
  if (typeof request.callback !== 'function') {
    throw new TypeError('Expected a callback function, got ' +
        typeof (request.callback) + ' instead.');
  }

  // We only need the callback from the first request.
  // The other callbacks can be safely ignored.
  if (isFirstRequest) {
    // This should be a user supplied callback or request-promise's callback.
    // The callback is always wrapped/bound to the request instance.
    options.callback = request.callback;
  }

  request.removeAllListeners('error')
    .once('error', function (error) {
      onRequestResponse(options, error);
    });

  request.removeAllListeners('complete')
    .once('complete', function (response, body) {
      onRequestResponse(options, null, response, body);
    });

  // Indicate that this is a cloudscraper request
  request.cloudscraper = true;
  return request;
}
function performRequest (options, isFirstRequest) {
  // This should be the default export of either request or request-promise.
  const requester = options.requester;

  // Note that request is always an instanceof ReadableStream, EventEmitter
  // If the requester is request-promise, it is also thenable.
  const request = requester(options);

  // We must define the host header ourselves to preserve case and order.
  if (request.getHeader('host') === HOST) {
    request.setHeader('host', request.uri.host);
  }

  // If the requester is not request-promise, ensure we get a callback.
  if (typeof request.callback !== 'function') {
    throw new TypeError('Expected a callback function, got ' +
        typeof (request.callback) + ' instead.');
  }

  // We only need the callback from the first request.
  // The other callbacks can be safely ignored.
  if (isFirstRequest) {
    // This should be a user supplied callback or request-promise's callback.
    // The callback is always wrapped/bound to the request instance.
    options.callback = request.callback;
  }

  request.removeAllListeners('error')
    .once('error', function (error) {
      onRequestResponse(options, error);
    });

  request.removeAllListeners('complete')
    .once('complete', function (response, body) {
      onRequestResponse(options, null, response, body);
    });

  // Indicate that this is a cloudscraper request
  request.cloudscraper = true;
  return request;
}
This function is wrapped to ensure that we get new options on first call. The options object is reused in subsequent calls when calling it directly.