At five years of experience, interviewers stop asking about syntax and start asking about architecture, trade-offs and impact. Here are the front-end developer interview questions for 5 years experience you should prepare for.
Architecture and System Design
Q: How would you design the front-end for a large-scale e-commerce platform? A: Discuss component architecture, state management strategy, code splitting and lazy loading, image optimisation, caching and CDN usage, error boundaries, and how you would keep the bundle size under control.
Q: How do you manage state in a large application? A: Evaluate options — local state, context for small shared state, and a solution like Redux or Zustand for complex global state. Discuss when each is appropriate and how to avoid prop drilling.
Q: How do you migrate a legacy codebase to a modern stack? A: Describe a phased approach: component-by-component migration, feature flags, keeping the site running during the transition, and adding tests as you go.
Performance Optimisation
Q: What causes Core Web Vitals failures and how do you fix them? A: LCP is affected by slow images and blocking scripts — fix with optimised images and lazy loading. INP relates to slow event handlers — fix with efficient code and avoiding long tasks. CLS is caused by layout shifts — fix by reserving space for images/ads.
Q: How do you reduce a large JavaScript bundle? A: Code splitting, tree shaking, removing unused dependencies, using dynamic imports, and choosing smaller libraries.
Q: How do you measure and monitor performance? A: Lighthouse, Web Vitals library, Real User Monitoring, and tracing in production.
Advanced JavaScript and React
Q: Explain how React reconciliation works. A: React diffs the virtual DOM by element type, keys and props to minimise real DOM updates. Keys help React track items across renders efficiently.
Q: How do you prevent unnecessary re-renders? A: Memoisation (useMemo, useCallback), memo on components, stabilising props, splitting state, and profiling with the React DevTools.
Q: What is the difference between useMemo and useCallback? A: useMemo caches a computed value; useCallback caches a function reference. Both optimise re-renders.
Q: How do you handle concurrent features and Suspense in React? A: Discuss lazy loading with Suspense, transitions for non-urgent updates, and how concurrent rendering keeps the UI responsive.
Testing and Quality
Q: What is your testing strategy? A: Test the behaviour users care about. Use unit tests for pure logic, integration tests for component interactions, and end-to-end tests for critical user journeys. Cover the risky paths, not 100% lines.
Q: How do you test for accessibility? A: Use automated tools like axe, manual keyboard navigation testing, screen-reader checks and following WCAG guidelines.
Leadership and Team Questions
Q: How do you review a colleague's code? A: Focus on correctness, readability and maintainability. Ask questions instead of giving commands, and suggest rather than dictate.
Q: How do you mentor junior developers? A: Pair programming, clear code reviews, providing small ownership tasks, and encouraging questions.
Q: Describe a technical decision you made and its trade-offs. A: Pick a real example: explain the options, the criteria you used, what you chose and why, and the outcome.
Conclusion
At five years of experience, your ability to make sound architectural decisions, communicate clearly and ship measurable results matters more than any single framework feature.
Need a senior front-end developer on your team? I bring five-plus years of production experience across Next.js, React and WordPress.
Malik Kashan
Frontend & WordPress Developer, Lahore, Pakistan