Function useFocusedKeyReset

packages/react-stately/src/list/useListState.ts:105–148

(
  collection: Collection<Node<T>>,
  selectionManager: SelectionManager
)

}

function useFocusedKeyReset<T>(
  collection: Collection<Node<T>>,
  selectionManager: SelectionManager
) {
  // Reset focused key if that item is deleted from the collection.
  const cachedCollection = useRef<Collection<Node<T>> | null>(null);
  useEffect(() => {
    if (
      selectionManager.focusedKey != null &&
      !collection.getItem(selectionManager.focusedKey) &&
      cachedCollection.current
    ) {
      // Walk forward in the old collection to find the next key that still exists in the new collection.
      let key = cachedCollection.current.getKeyAfter(selectionManager.focusedKey);
      let nextFocusedKey: Key | null = null;
      while (key != null) {
        let node = collection.getItem(key);
        if (node && node.type === 'item' && !selectionManager.isDisabled(key)) {
          nextFocusedKey = key;
          break;
        }

        key = cachedCollection.current.getKeyAfter(key);
      }

      // If no such key exists, walk backward.
      if (nextFocusedKey == null) {
        key = cachedCollection.current.getKeyBefore(selectionManager.focusedKey);
        while (key != null) {
          let node = collection.getItem(key);
          if (node && node.type === 'item' && !selectionManager.isDisabled(key)) {
            nextFocusedKey = key;
            break;
          }

          key = cachedCollection.current.getKeyBefore(key);
        }
      }

      selectionManager.setFocusedKey(nextFocusedKey);
    }
    cachedCollection.current = collection;
  }, [collection, selectionManager]);
}