code: function(ev) {
          var $target = $(ev.target);
          var columnName = $target.closest('th').attr(ATTR_COLUMN_NAME);
          var eventData = new GridEvent(ev);
  
          if (columnName === '_button' && $target.is('input')) {
              eventData.setData({
                  checked: $target.prop('checked')
              });
              this.domEventBus.trigger('click:headerCheck', eventData);
          } else if ($target.is('a.' + classNameConst.BTN_SORT)) {
              eventData.setData({
                  columnName: columnName
              });
              this.domEventBus.trigger('click:headerSort', eventData);
          }
      }
docs: Event handler for click event
  @param {jQuery.Event} ev - MouseEvent
  @private