code: function ajaxError(error, type, xhr, settings) {
      var context = settings.context
      settings.error.call(context, xhr, type, error)
      triggerGlobal(settings, context, 'ajaxError', [xhr, settings, error])
      ajaxComplete(type, xhr, settings)
    }
docs: type: "timeout", "error", "abort", "parsererror"