Function insertBefore

packages/react-stately/src/data/useListData.ts:249–262

(key: Key, ...values: T[])

      dispatch(state => insert(state, index, ...values));
    },
    insertBefore(key: Key, ...values: T[]) {
      dispatch(state => {
        let index = state.items.findIndex(item => getKey?.(item) === key);
        if (index === -1) {
          if (state.items.length === 0) {
            index = 0;
          } else {
            return state;
          }
        }

        return insert(state, index, ...values);
      });
    },
    insertAfter(key: Key, ...values: T[]) {
      dispatch(state => {
        let index = state.items.findIndex(item => getKey?.(item) === key);