code: function (elementId) {
        var element = this.getElement(elementId);
        var errObj = new ERROR.UnknownError(
          'elementId ' + elementId + ' could not be tapped');
        if (element !== null) {
          try {
            // element may still be null.
            element.tap();
          } catch (e) {
            if (e.message.indexOf("(null)") !== -1) {
              try {
                $.target().tap(element.rect());
              } catch (e2) {
                throw errObj;
              }
            } else {
              throw errObj;
            }
          }
        } else {
          throw new ERROR.UnknownError(
            'elementId ' + elementId + ' is null and can\'t be tapped.');
        }
      }
docs: Gesture functions