@blueprintjs/core
Version:
Core styles & components
28 lines • 1.08 kB
JavaScript
/*
* Copyright 2022 Palantir Technologies, Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import * as React from "react";
/** React hook which tracks the previous state of a given value. */
export function usePrevious(value) {
// create a new reference
const ref = React.useRef();
// store current value in ref
React.useEffect(() => {
ref.current = value;
}, [value]);
// return previous value (happens before update in useEffect above)
return ref.current;
}
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