code: function() {
          var self = this;
          this.$main.on('click.bizTableSort', '.biz-table-head .sortable', function(e) {
              var head = $(this),
                  field = head.parent().attr('field');
              if (head.attr('des') !== undefined) {
                  self.removeSort();
                  head.attr('asc', '');
              } else if (head.attr('asc') !== undefined) {
                  self.removeSort();
                  head.attr('des', '');
              } else {
                  self.removeSort();
                  head.attr(self.options.defaultSort === 'des' ? 'des' : 'asc', '');
              }
              self.options.onSort.call(self, {
                  field: field,
                  des: head.attr('des') !== undefined,
                  asc: head.attr('asc') !== undefined
              }, e);
          });
      }
docs: 绑定排序事件
  @private