AjaxResponseSubscriber::onResponse

public AjaxResponseSubscriber::onResponse(FilterResponseEvent $event)

public function onResponse(FilterResponseEvent $event) {
  $response = $event->getResponse();
  if ($response instanceof AjaxResponse) {
    $this->ajaxResponseAttachmentsProcessor->processAttachments($response);

    // IE 9 does not support XHR 2 (http://caniuse.com/#feat=xhr2), so
    // for that browser, jquery.form submits requests containing a file upload
    // via an IFRAME rather than via XHR. Since the response is being sent to
    // an IFRAME, it must be formatted as HTML. Specifically:
    // - It must use the text/html content type or else the browser will
    //   present a download prompt. Note: This applies to both file uploads
    //   as well as any ajax request in a form with a file upload form.
    // - It must place the JSON data into a textarea to prevent browser
    //   extensions such as Linkification and Skype's Browser Highlighter
    //   from applying HTML transformations such as URL or phone number to
    //   link conversions on the data values.
    //
    // Since this affects the format of the output, it could be argued that
    // this should be implemented as a separate Accept MIME type. However,
    // that would require separate variants for each type of AJAX request
    // (e.g., drupal-ajax, drupal-dialog, drupal-modal), so for expediency,
    // this browser workaround is implemented via a GET or POST parameter.
    //
    // @see http://malsup.com/jquery/form/#file-upload
    // @see https://www.drupal.org/node/1009382
    // @see https://www.drupal.org/node/2339491
    // @see Drupal.ajax.prototype.beforeSend()
    $accept = $event->getRequest()->headers->get('accept');

    if (strpos($accept, 'text/html') !== FALSE) {
      $response->headers->set('Content-Type', 'text/html; charset=utf-8');

      // Browser IFRAMEs expect HTML. Browser extensions, such as Linkification
      // and Skype's Browser Highlighter, convert URLs, phone numbers, etc.
      // into links. This corrupts the JSON response. Protect the integrity of
      // the JSON data by making it the value of a textarea.
      // @see http://malsup.com/jquery/form/#file-upload
      // @see https://www.drupal.org/node/1009382
      $response->setContent('<textarea>' . $response->getContent() . '</textarea>');
    }

    // User-uploaded files cannot set any response headers, so a custom header
    // is used to indicate to ajax.js that this response is safe. Note that
    // most Ajax requests bound using the Form API will be protected by having
    // the URL flagged as trusted in Drupal.settings, so this header is used
    // only for things like custom markup that gets Ajax behaviors attached.
    $response->headers->set('X-Drupal-Ajax-Token', 1);
  }
}