去重複

                  //去重複
                  var res = [];
                  var json = {};
                  for(var i = this.checkedData.length-1; i >= 0; i--){
                      if(!json[this.checkedData[i].permission_id]){  //如果有不一樣的permission_id
                          res.push(this.checkedData[i]);
                          json[this.checkedData[i].permission_id]= 1;
                      }
                  }