code: function(hide){
        var othis = $(this)
        ,elemCell = othis.children(ELEM_CELL);
        
        if(hide){
          othis.find('.layui-table-grid-down').remove();
        } else if(elemCell.prop('scrollWidth') > elemCell.outerWidth()){
          if(elemCell.find('.'+ ELEM_GRID_DOWN)[0]) return;
          othis.append('<div class="'+ ELEM_GRID_DOWN +'"><i class="layui-icon layui-icon-down"></i></div>');
        }
      }
docs: 单元格展开图标