Interview prep
Frontend Developer interview questions
Frontend interviews test component design, JavaScript fundamentals, performance optimization, and system thinking. Expect coding challenges (DOM, state), design patterns, and architectural decisions.
🎤 Practice these out loud with AceCoach →The questions
Design a React date-range picker that works on mobile and desktop. How do you handle state and performance? System design
How to answerComponent hierarchy, state shape (start/end, open/closed), memoization, mobile touch UX, accessibility (ARIA, keyboard nav).
Implement a function that cancels the previous API request when a new one starts (race condition). Coding
How to answerUse AbortController to cancel the prior fetch, store it in a ref, clean up on unmount, test with rapid clicks.
Your page's LCP is 3.2s. Walk me through debugging and optimizing it. Scenario
How to answerProfile in DevTools to find the blocker, then lazy-load images, code-split JS, preload fonts, reduce main-thread work, and measure.
Tell me about a feature you shipped that hurt performance and how you fixed it. Behavioral
How to answerSTAR: feature, regression observed, profiling + refactor, restored latency and added guardrails (lint/CI budget).
Explain event delegation and when you'd use it over direct listeners. Fundamentals
How to answerAttach one listener on a parent, inspect event.target; use for dynamic DOM and many similar elements; note bubbling limits.
Design a component-library architecture. How do you ensure consistency and avoid prop drilling? System design
How to answerBase/composite components + hooks, theming via context/CSS vars, Storybook docs, composition patterns (compound components, slots).
What frontend developers are tested on
React/Vue/AngularJavaScript (ES6+)CSS/Responsive DesignPerformance OptimizationTypeScriptTesting (Jest/Vitest)REST APIsBrowser DevTools
Frameworks are guidance, not scripts — the point is to make the answers your own. All roles →