What are the most common frontend interview questions?

The most common frontend interview questions cover JavaScript fundamentals (event loop, closures, async/await, prototypes), React (hooks like useState/useEffect/useMemo, reconciliation, performance optimization), CSS and layout (flexbox, grid, specificity), frontend system design (autocomplete, infinite scroll, design a YouTube player), and behavioral questions.

What is a machine coding round in a frontend interview?

A machine coding round is a live coding session where you build a functional UI component or mini-application from scratch — for example, an autocomplete search, a Kanban board, a star rating widget, or an infinite scroll list. It tests your ability to write clean, maintainable code under time pressure. Machine coding rounds are common at Indian tech companies like Flipkart, Swiggy, Razorpay, and CRED.

How do I prepare for React interview questions?

To prepare for React interview questions, focus on: (1) React hooks — useState, useEffect, useCallback, useMemo, useRef, and custom hooks; (2) Reconciliation and the virtual DOM; (3) Performance optimization — React.memo, lazy loading, code splitting; (4) State management patterns — Context API, Redux, Zustand; (5) Component design patterns. Practice by building components from scratch and getting AI feedback on your code.

What frontend interview questions are asked for 3+ years of experience?

For engineers with 3+ years of experience, interviewers expect depth in React architecture, performance optimization, TypeScript, frontend system design (designing scalable component libraries, state machines, API layers), and behavioral questions about owning features end-to-end. Machine coding rounds will expect production-quality code with error handling and edge cases.

Interview Questions

Frontend Interview Questions

Realistic question sets for JavaScript, React, and frontend system design. In the simulator, your answers are evaluated with AI scoring and converted into personalized prep plans.

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Practice Real Interview Problems

How answer evaluation works

AI-powered scoring

Targeted prep modules

Interview-realistic format

Practice with real-time AI feedback

Practice Real Interview Problems

Design a Capacity-Aware LRU Cache with Variable Item Sizes

Implement Debounce: Rate-Limiting Function Execution

Reverse a Singly Linked List Iteratively

Array Pair Sum: Find Indices for Target Value (Two Sum)

Syntax Validation: Nested Parentheses and Contextual Brackets

Count Pairs with Target Difference in Sorted Array (Two Pointers)

Build a Robust useFetch Hook in React with Loading & Error States

Build an Accessible React Tabs Component with Dynamic Content

React Autocomplete Search: Dynamic Destination Typeahead UI

Build a React Star Rating Widget with Hover & Selection

Build a Dynamic React Accordion Component with State

React Product Catalog: Real-Time Search, Filter & Sort

Build a Flexible React OTP Input Component with Accessibility

React Multi-step Form with State Machine & Validation

React File Explorer: Dynamic Tree View with CRUD & Accessibility

React Draggable Kanban Board: Sortable Columns & Items

React Infinite Scroll Feed: Async Data Fetch & Performance

Build a React Highly-Available Multi-Select Chip Input

Offline-First Collaborative To-Do PWA Design

Frontend System Design: Real-time Chat with Scalability and Offline Support

E-commerce Product Listing: Scalable Frontend Design

Architecting a Real-Time, Personalized News Feed Frontend

Frontend Analytics SDK: High-Scale, Privacy-Centric Event Ingestion Design

Frontend Design: Scalable E-commerce Shopping Cart UI

Practice Real Interview Problems

How answer evaluation works

AI-powered scoring

Targeted prep modules

Interview-realistic format

Practice with real-time AI feedback

Practice Real Interview Problems

Design a Capacity-Aware LRU Cache with Variable Item Sizes

Implement Debounce: Rate-Limiting Function Execution

Reverse a Singly Linked List Iteratively

Array Pair Sum: Find Indices for Target Value (Two Sum)

Syntax Validation: Nested Parentheses and Contextual Brackets

Count Pairs with Target Difference in Sorted Array (Two Pointers)

Build a Robust useFetch Hook in React with Loading & Error States

Build an Accessible React Tabs Component with Dynamic Content

React Autocomplete Search: Dynamic Destination Typeahead UI

Build a React Star Rating Widget with Hover & Selection

Build a Dynamic React Accordion Component with State

React Product Catalog: Real-Time Search, Filter & Sort

Build a Flexible React OTP Input Component with Accessibility

React Multi-step Form with State Machine & Validation

React File Explorer: Dynamic Tree View with CRUD & Accessibility

React Draggable Kanban Board: Sortable Columns & Items

React Infinite Scroll Feed: Async Data Fetch & Performance

Build a React Highly-Available Multi-Select Chip Input

Offline-First Collaborative To-Do PWA Design

Frontend System Design: Real-time Chat with Scalability and Offline Support

E-commerce Product Listing: Scalable Frontend Design

Architecting a Real-Time, Personalized News Feed Frontend

Frontend Analytics SDK: High-Scale, Privacy-Centric Event Ingestion Design

Frontend Design: Scalable E-commerce Shopping Cart UI