15 common useEffect mistakes to avoid in your React apps

React's useEffect Hook is widely misused, causing unnecessary re-renders and performance issues in applications. Common mistakes include missing dependency arrays that create infinite loops, using effects for derived state calculations that should happen during rendering, and failing to properly clean up external resources like fetch requests or event listeners. Understanding that useEffect should synchronize with external systems rather than handle user interactions or compute values from existing state helps developers choose the right approach for cleaner, faster React apps.