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React Performance Optimization Using useMemo And useCallback Hooks

JavaScript JavaScript / jQuery August 9, 2026

This React pattern optimizes performance in functional components by preventing unnecessary re-renders using the useMemo and useCallback hooks. It is particularly useful when dealing with complex computations or expensive function calls, significantly enhancing application performance. The useMemo hook memoizes values, while the useCallback hook memoizes functions, both improving efficiency. By applying this pattern, developers can optimize their React applications for better user experience.

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/**
       * Optimized React component that utilizes useMemo and useCallback for performance enhancement.
       * 
       * @param {object} props - The component props.
       * @param {function} props.expensiveFunction - An expensive function to be memoized.
       * @param {array} props.dependencyArray - Dependency array for useMemo.
       * @return {JSX.Element} The component markup.
       */
      import React, { useMemo, useCallback } from 'react';

      const OptimizedComponent = ({ expensiveFunction, dependencyArray }) => {
         // Memoize the expensive function using useCallback to prevent re-renders.
         const memoizedExpensiveFunction = useCallback(expensiveFunction, dependencyArray);

         // Memoize a value using useMemo to prevent recalculations.
         const memoizedValue = useMemo(() => {
            // Simulating an expensive computation.
            return Array(1000000).fill(0).map((_, index) => index);
         }, dependencyArray);

         return (
            <div>
               <h1>Optimized Component</h1>
               <button onClick={memoizedExpensiveFunction}>Trigger Expensive Function</button>
               <p>Memoized Value: {memoizedValue.length}</p>
            </div>
         );
      };

      export default OptimizedComponent;

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