Files F99418856

useUpdateEffect.js
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Created: Fri, Jan 24, 09:37

useUpdateEffect.js
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	import { useEffect, useRef } from 'react';
	/**
	* Runs an effect only when the dependencies have changed, skipping the
	* initial "on mount" run. Caution, if the dependency list never changes,
	* the effect is never run
	*
	* ```ts
	* const ref = useRef<HTMLInput>(null);
	*
	* // focuses an element only if the focus changes, and not on mount
	* useUpdateEffect(() => {
	* const element = ref.current?.children[focusedIdx] as HTMLElement
	*
	* element?.focus()
	*
	* }, [focusedIndex])
	* ```
	* @param effect An effect to run on mount
	*
	* @category effects
	*/

	function useUpdateEffect(fn, deps) {
	var isFirst = useRef(true);
	useEffect(function () {
	if (isFirst.current) {
	isFirst.current = false;
	return;
	}

	return fn();
	}, deps);
	}

	export default useUpdateEffect;

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