function useRecoilValueLoadable_SYNC_EXTERNAL_STORE()

in packages/recoil/hooks/Recoil_Hooks.js [298:356]

• 54 lines of code
• 5 McCabe index (conditional complexity)

function useRecoilValueLoadable_SYNC_EXTERNAL_STORE<T>(
  recoilValue: RecoilValue<T>,
): Loadable<T> {
  const storeRef = useStoreRef();
  const componentName = useComponentName();

  const getSnapshot = useCallback(() => {
    if (__DEV__) {
      recoilComponentGetRecoilValueCount_FOR_TESTING.current++;
    }
    const store = storeRef.current;
    const storeState = store.getState();
    const treeState = reactMode().early
      ? storeState.nextTree ?? storeState.currentTree
      : storeState.currentTree;
    const loadable = getRecoilValueAsLoadable(store, recoilValue, treeState);
    return {loadable, key: recoilValue.key};
  }, [storeRef, recoilValue]);

  // Memoize the state to avoid unnecessary rerenders
  const memoizePreviousSnapshot = useCallback(getState => {
    let prevState;
    return () => {
      const nextState = getState();
      if (
        prevState?.loadable.is(nextState.loadable) &&
        prevState?.key === nextState.key
      ) {
        return prevState;
      }
      prevState = nextState;
      return nextState;
    };
  }, []);
  const getMemoizedSnapshot = useMemo(
    () => memoizePreviousSnapshot(getSnapshot),
    [getSnapshot, memoizePreviousSnapshot],
  );

  const subscribe = useCallback(
    notify => {
      const store = storeRef.current;
      const subscription = subscribeToRecoilValue(
        store,
        recoilValue,
        notify,
        componentName,
      );
      return subscription.release;
    },
    [storeRef, recoilValue, componentName],
  );

  return useSyncExternalStore(
    subscribe,
    getMemoizedSnapshot, // getSnapshot()
    getMemoizedSnapshot, // getServerSnapshot() for SSR support
  ).loadable;
}