React setState hook typescript (merge)

useMergeState.ts

function isSimpleObject(value: any): boolean {
  return !!value && value.constructor === Object;
}

function useMergeState<T>(initialState?: T) {
  const [mergeState, setMergeState] = isSimpleObject(initialState)
    ? React.useState<T>(initialState as T)
    : React.useState<Partial<T>>();

  const setState = React.useCallback((newState: Partial<T>) => {
    if (isSimpleObject(newState)) {
      setMergeState((state: any) =>
        (state as T) ? { ...state, ...newState } : newState
      );
    }
  }, []);

  return [mergeState, setState] as [T | undefined, typeof setMergeState];
}
  
export default useMergeState;