Full Stack Developer Interview Questions (Practice with AI Feedback)

"To sync state, I use React Query on the frontend for automatic caching, background refetching, and query invalidation. For real-time updates, like chat or notification feeds, I establish a WebSocket connection. I also implement optimistic UI updates, rendering the updated state instantly in the UI before server confirmation, rolling it back only if the API call fails."

"To prevent Cross-Site Scripting (XSS), I sanitize and escape all user input before rendering, and implement a strict Content Security Policy (CSP). To block Cross-Site Request Forgery (CSRF), I use SameSite=Strict flags on session cookies and require anti-CSRF tokens in the headers of all modifying state requests (POST/PUT)."

"I optimize end-to-end performance by placing static assets on a global CDN and using edge middleware to handle redirects. I compress high-resolution media using responsive image sizes, lazy load assets, and implement database indexing on the backend query paths to keep API response times under 100ms."