Interview questions (prompt-only)

This file contains interview questions only (no answers). Answers live in content/interviews/answers.mdx.

General / mindset

• What’s the difference between unit, integration, and E2E tests? When would you use each?
• How do you decide what runs on the server vs the client in a Next.js app?

TypeScript

• Explain unknown vs any. When should you use unknown?
• What is type narrowing? Give an example.

Next.js (App Router)

• What’s the difference between Server Components and Client Components?
• How do loading.tsx and error.tsx work in App Router?

tRPC

• What problem does tRPC solve compared to REST?
• Where should authentication/authorization checks live in a tRPC app?

Tailwind

• How do you keep Tailwind-based UIs maintainable as the app grows?

Vitest

• What makes a test brittle? How do you avoid it?

Playwright

• What makes E2E tests flaky? How do you reduce flakiness in CI?

Debouncing (React / Zod / data fetching)

• What is debouncing? What problems does it solve in UI development?
• Zod forms: when would you validate onChange vs onBlur vs onSubmit? Where does debouncing fit?
• tRPC: how do you debounce an “availability check” query and ensure stale responses can’t win?
• useEffect + fetch: how do you debounce a search request and cancel/ignore stale requests?