packages/@fbcmobile-ui/Hooks/useMountedState.js

/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow strict-local
 * @format
 */

'use strict';

import {useCallback, useEffect, useRef} from 'react';

export default (): (() => boolean) => {
  const mountedRef = useRef<boolean>(false);

  useEffect(() => {
    mountedRef.current = true;

    return () => {
      // The cleanup function of useEffect is called by React on unmount
      mountedRef.current = false;
    };
  }, []);

  return useCallback(() => mountedRef.current, []);
};