date: 2025-08-14 topics: [Next.js, TypeScript, Authentication, Error-Handling] day: 28

Day 28 – Frontend and Debugging

✅ Work Done

Frontend: Fixed ESLint warnings, debugged API route types, implemented NextAuth credential login with server-only tokens, built dynamic user profile page, handled cross-domain cookies, added toast notifications.
DSA Practice: Check Even/Odd, Multiplication Table, Sum of Naturals & Squares, Swap Numbers, Closest Number, Dice Problem, Nth Term of AP.

📚 Key Learnings

Next.js 15+ API routes require await params.
Server-only tokens improve security; TypeScript interfaces prevent runtime errors.
Cross-domain cookies need SameSite=None and Secure.
Mathematical formulas optimize iterative solutions; multiple swap techniques; edge case handling.

❌ Blockers

Route param mismatches, NextAuth session config, TypeScript strict types, ESLint deps rules.
Overthinking simple DSA problems, forgetting edge cases, formula mix-ups.

🧠 Reflection Next.js 15 brings breaking changes; careful state management, async handling, and error feedback are key. DSA practice complements frontend debugging and builds problem-solving confidence.