Frontend Developer 路 Intern to senior
Frontend interviews combine language fundamentals (closures, the event loop, async code) with framework knowledge and an understanding of how the browser renders and updates the page.
93 questions
Take heap snapshots in Chrome DevTools before and after the suspect action, compare what grew, and fix the retaining reference, which is usually a forgotten listener, timer, global variable or unbounded cache.
A component re-renders when its state changes, its parent re-renders, or a context it consumes changes; you prevent wasted renders by moving state down, using React.memo, and keeping props referentially stable.
Measure first with the Profiler and Lighthouse, then reduce unnecessary renders, split code with lazy loading, virtualise long lists, and optimise images and bundle size.
Core Web Vitals are Google鈥檚 field metrics for real-user experience: LCP (loading), INP (interactivity) and CLS (visual stability). They influence search ranking and are measured on real devices, not only Lighthouse.
Mapped types build a new object type by looping over keys (`{ [K in keyof T]: ... }`). Conditional types pick a result with `T extends U ? X : Y`, which is how many utility types are implemented.
Show how you built trust, understood competing concerns, used evidence and helped the group reach a decision.
Explain the constraints, alternatives, trade-offs, decision criteria and why the chosen option was appropriate for the context.
Cover detection, communication, mitigation, investigation, recovery and the changes made afterwards to reduce recurrence.
Explain why the technology looked attractive, what problem it actually solved, and why its cost or complexity was not justified in your context.
Explain the deadline, the quality risks, what you protected, what you simplified and how you managed any remaining debt.
Explain the original reasoning, the evidence that changed your view, how you corrected course and what decision-making practice improved afterwards.
Walk through how you shaped the problem, planned the work, aligned stakeholders, managed risks and measured the outcome.
Show empathy, clear expectations, practical support and appropriate escalation rather than blame.