Ernst and young

Role: React.js Frontend Engineer

College: Not Specified

Interview Date: 2025-03-11

Interview Type: Not Specified

Result: Selected (Offer received, but declined)

Difficulty: Medium

Rounds: Multiple rounds

Topics Asked: JavaScript Fundamentals (var, let, const, function declarations, function expressions, arrow functions, hoisting, bindings, closures, lexical scope), React.js (Virtual DOM, diffing algorithm, reconciliation, hooks, custom hooks, useMemo, useCallback, functional vs. class components, lifecycle methods, state management with useState, useReducer, Context API, Redux, Zustand, keys in React lists), Optimization, Frontend best practices, Security.

Experience:

The interview process for a React.js Frontend Engineer role at Ernst & Young involved multiple rounds covering JavaScript fundamentals, React concepts, problem-solving, and frontend best practices.

Technical Round 1: The Foundation Test (Virtual)
This round focused on JavaScript and React.js, with a mix of theoretical and coding questions.

JavaScript Fundamentals: Questions included differences between variables and functions (var, let, const vs. function declarations, expressions, arrow functions), and explanations of hoisting, bindings, and closures with examples (including lexical scope).

React.js Essentials: Questions covered how the React Virtual DOM works for performance (diffing algorithm, reconciliation), advantages of hooks and custom hooks (cleaner code, stateful logic reuse, performance with useMemo and useCallback), differences between functional and class components (lifecycle methods vs. hooks, readability, performance), and state management patterns (useState, useReducer, Context API, Redux, Zustand). The purpose of keys in React lists for efficient element identification was also asked.

Optimization & Best Practices: This section covered general optimization and frontend best practices.

After successfully clearing all rounds, the candidate received an offer from EY but chose to decline it for another opportunity.

Key Learnings: Master JavaScript fundamentals, deep dive into React internals, understand performance and optimization, prioritize security and best practices, and systematic problem-solving.