🔥IBM Frontend Engineer Interview Breakdown (15 LPA) — React + JavaScript Questions Explained

Overview

The candidate successfully navigated the IBM frontend engineer interview process, securing a role with a compensation of 15 LPA. The process involved multiple rounds, assessing both coding abilities and understanding of frontend architecture principles. The application was initiated through a direct call from Naukri.com based on the candidate's profile and tech stack.

Interview Rounds

The interview process consisted of several rounds, each designed to evaluate different aspects of the candidate's skills and experience.

Phone Screening Round:

• A preliminary introduction to verify experience in React UI projects and real-world problem-solving.
• A high-level discussion of the candidate's profile, responsibilities, and availability.

Round 1 — Technical Coding (Hands-On + React Internals):

This round involved practical coding tasks and in-depth technical discussions.

• Coding Tasks:

  | Area | Task | | ------------------- | ----------------------------------------------------------------------------------------- | | React + Performance | Write a function to debounce an API call and integrate it into a search component | | Custom Hooks | Build a useFetch hook with AbortController cancellation support | | DOM + JavaScript | Create a dynamic table with sorting and pagination — no external libraries |

• Deep Technical Discussions:

  • React Fiber architecture and rendering phases
  • Virtual DOM diffing and reconciliation
  • Preventing re-renders using memo, useCallback, and useMemo
  • Event Loop — microtasks vs. macrotasks

Round 2 — Tech Lead Discussion (Real-World IBM Scenarios):

This round focused on large-scale frontend architecture and system design for UI.

• Architecture Questions:

  • Walkthrough of a complex UI project
  • State management strategy: Redux vs. Context vs. Recoil
  • Rendering 10k+ records efficiently using windowing (React Virtualized)

• Live Coding Challenge:

  • Build a dashboard widget to show Top 5 performing items with:
    • Sorting logic
    • API polling using setInterval
    • Cleanups with useEffect
    • Error handling + retry strategy

• Additional Discussions:

  • Webpack optimization & bundling
  • Tree-shaking, code splitting, lazy loading
  • Reducing bundle size & improving page load time

Managerial Round — Beyond Coding:

This round evaluated ownership mindset and team collaboration.

• Key discussions included:
  • Working with backend teams, designers, and QA
  • Handling performance issues in production
  • Meeting accessibility standards (WCAG / ARIA)
  • Delivering critical UI features under tight deadlines
  • Decision-making and communication approach

Key Takeaways

The IBM frontend engineer interview process emphasizes a strong foundation in JavaScript and React, along with practical experience in building and optimizing user interfaces. Candidates should be prepared to discuss performance considerations, frontend architecture, and collaboration within cross-functional teams. A deep understanding of React internals and the ability to solve problems under real product constraints are also crucial for success.