Accessibility (a11y) in React Animation in React (Framer Motion & React Spring) Build Tools & Bundlers (Vite, Webpack & CRA) Class Components & Legacy Lifecycle Methods Code Splitting & Lazy Loading Component Composition & Children Props Components & JSX Concurrent Hooks (useTransition, useDeferredValue & useLayoutEffect) Conditional Rendering & Lists (Keys) Context API Custom Hooks Data Fetching (React Query & SWR) Deployment & Production Builds Design Patterns in React Effects & Lifecycle Error Boundaries Forms: Controlled & Uncontrolled Components Higher-Order Components (HOCs) Hooks Internationalization (i18n) in React Performance (memo/useMemo) Portals & Fragments Props & State React DevTools & Debugging Refs, useRef & forwardRef Render Props Pattern Routing Security in React (XSS & dangerouslySetInnerHTML) Server Actions & Data Mutations Server Components Server-Side Rendering (SSR) & Next.js State Management State Management Libraries (Redux, Zustand & Recoil) Static Site Generation (SSG) & Hydration Strict Mode & Concurrent Features Styling in React (CSS Modules, Styled Components & Tailwind) Suspense & Concurrent Rendering Testing TypeScript with React useReducer & Complex State Logic Virtual DOM & Reconciliation