docs: function(callback, data){
          data = data || this._dataCache;
          var _this = this, i = 0, flag = true;
          for(i; i < data.length; i++){
              if(data[i].type == 'group'){
                  flag = _this.each(callback, data[i].value);
              }else{
                  flag = callback.call(data[i], data[i]);
              }
              if(flag == false){
                  break;
              }
          }
          return flag;
      }