JAVASCRIPT

React usePrevious Hook to Track Previous State

Discover how to implement a usePrevious hook in React to easily access the prior value of a prop or state, essential for comparisons within useEffect or other logic.

import { useRef, useEffect } from 'react';

function usePrevious(value) {
  const ref = useRef();

  useEffect(() => {
    ref.current = value;
  }, [value]);

  return ref.current;
}
How it works: The `usePrevious` hook allows you to get the value that a prop or state had on the previous render. It stores the current value in a `useRef` on each render and returns its value from the *previous* render. This is particularly useful for comparing current and past values within a `useEffect` hook to trigger specific side effects.

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