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Текущая директория: /usr/lib/node_modules/bitgo/node_modules/react-native/Libraries/Utilities
Просмотр файла: useRefEffect.js
/**
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @flow strict
* @format
*/
import {useCallback, useRef} from 'react';
type CallbackRef<T> = T => mixed;
/**
* Constructs a callback ref that provides similar semantics as `useEffect`. The
* supplied `effect` callback will be called with non-null component instances.
* The `effect` callback can also optionally return a cleanup function.
*
* When a component is updated or unmounted, the cleanup function is called. The
* `effect` callback will then be called again, if applicable.
*
* When a new `effect` callback is supplied, the previously returned cleanup
* function will be called before the new `effect` callback is called with the
* same instance.
*
* WARNING: The `effect` callback should be stable (e.g. using `useCallback`).
*/
export default function useRefEffect<TInstance>(
effect: TInstance => (() => void) | void,
): CallbackRef<TInstance | null> {
const cleanupRef = useRef<(() => void) | void>(undefined);
return useCallback(
(instance: null | TInstance) => {
if (cleanupRef.current) {
cleanupRef.current();
cleanupRef.current = undefined;
}
if (instance != null) {
cleanupRef.current = effect(instance);
}
},
[effect],
);
}
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