Function insert

packages/react-stately/src/data/useListData.ts:246–248

(index: number, ...values: T[])

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