code: function () {
                                  if (slotInsertBefore) {
                                      var itemNew = {
                                          key: keyUpdate.key,
                                          data: data
                                      };
  
                                      keyUpdate.slot = insertNewSlot(keyUpdate.key, itemNew, slotInsertBefore, append, !append);
                                  }
                              }
docs: updateSlots