Function useSelector

packages/xstate-store-react/src/index.ts:152–183

(
  store: Readable<TSnapshot>,
  selector?: (snapshot: TSnapshot) => T,
  compare: (a: T | undefined, b: T) => boolean = defaultCompare
)

  compare?: (a: TSnapshot | undefined, b: TSnapshot | undefined) => boolean
): TSnapshot;
export function useSelector<TSnapshot, T>(
  store: Readable<TSnapshot>,
  selector?: (snapshot: TSnapshot) => T,
  compare: (a: T | undefined, b: T) => boolean = defaultCompare
): T | TSnapshot {
  const subscribe = useCallback(
    (handleStoreChange: () => void) =>
      store.subscribe(handleStoreChange).unsubscribe,
    [store]
  );

  if (!selector) {
    const selectorWithCompare = useSelectorWithCompare(
      identity,
      defaultCompare
    );

    return useSyncExternalStore(
      subscribe,
      () => selectorWithCompare(store.get()),
      () => selectorWithCompare(store.get())
    );
  }

  const selectorWithCompare = useSelectorWithCompare(selector, compare);

  return useSyncExternalStore(
    subscribe,
    () => selectorWithCompare(store.get()),
    () => selectorWithCompare(store.get())
  );
}

/** Creates a stable store instance for the lifetime of a React component. */
export function useStore<TDefinition extends StoreDefinition>(