code: function on_error(xhr, status, error) {
  	var response = new anchor._response_handler(null);
  	response.okay(false);
  	response.message(error);
  	response.message_type(status);
  	anchor.apply_callbacks('error', [response, anchor]);
      }
docs: What to do if an error is triggered. Remember that with jQuery, when using JSONP, there is no error.