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🚀 My Sense Frontend Engineer Interview Experience (2025) | Senior UI Developer

Gourav Hammad

• 5 min read
Sense Company Logo
Sense Company Logo

Frontend interviews at top product-based companies test far more than your UI skills—they assess your problem-solving ability, architectural thinking, and code clarity. I recently interviewed at Sense, and this article breaks down my complete journey—DSA questions, advanced JavaScript challenges, system design discussions, and hands-on machine coding.

If you're preparing for frontend roles at startups or FAANG-level companies, this is your blueprint. Let’s dive in! 👇

🧩 Interview Process Overview

The Sense interview process spanned 5 rounds, focusing on:

  1. Data Structures & Algorithms (DSA)
  2. Advanced JavaScript + Frontend Concepts
  3. System Design for Scalable UI
  4. Machine Coding (React Component Building)
  5. Behavioral & Hiring Manager Round

💡 Round 1: Data Structures & Algorithms

🧪 Binary Search — Recursive Implementation

Task: Implement Binary Search in JavaScript from scratch.

// 🔍 Binary Search using Recursion in JavaScript
function binarySearch(list = [], targetElement = 0) {
  // 📏 Step 1: Get the length of the current list
  let listLength = list.length;

  // 🎯 Step 2: Calculate the middle index
  let middleIndex = Math.floor(listLength / 2);

  // ✅ Step 3: Check if the middle element matches the target
  if (list[middleIndex] === targetElement) return true;

  // ❌ Step 4: If the list has only one element and it's not the target
  if (list.length === 1) return false;

  // 🔁 Step 5: Recursively search in the left or right half of the list
  return list[middleIndex] > targetElement
    ? binarySearch(list.slice(0, middleIndex), targetElement) // 👈 Search in the left half
    : binarySearch(list.slice(middleIndex), targetElement);   // 👉 Search in the right half
}

// 📋 Sample sorted list to test the function
let sortedList = [1, 2, 3, 4, 5, 15, 20, 25, 100];

// 🧪 Test Cases
console.log(binarySearch(sortedList, 21)); // ❌ false - not found
console.log(binarySearch(sortedList, 20)); // ✅ true - found

Problem Statement

🔍 Notes:

  • This is a recursive implementation of binary search.
  • It's based on divide-and-conquer, repeatedly halving the array.
  • Complexity: O(log n) time for sorted arrays.
  • list.slice(...) creates a new array in each recursion, which uses extra memory. A more memory-efficient version would use start and end indices instead.

✅ Other DSA Questions:

  • 🔄 Shallow vs Deep Cloning — With custom deep clone implementation
  • 🔁 Handling Circular References in Object Deep Copy Logic
  • 🧠 object.keyName vs object[keyName] — JavaScript key access patterns
🔥 Pro Tip: Focus on recursion, hash maps, array/object manipulation, and edge cases. Practice on LeetCode, JavaScript.info, and GeeksforGeeks.

💡 Round 2: Advanced JavaScript

1️⃣ SSR vs CSR — Which is better for frontend performance?

✅ Server-Side Rendering (SSR) advantages:
  • SEO-friendly out of the box (better crawlability)
  • Faster initial page load (especially on slow networks)
  • Better Core Web Vitals — improved LCP (Largest Contentful Paint)

2️⃣ Implement flow() like Lodash

Task: Chain functions together and process input sequentially.

// 🔁 flow: Composes multiple functions from left to right
const flow = (...funcs) => (arg) =>
  funcs.reduce((res, fn) => fn(res), arg);
// 🧠 Explanation:
// - Accepts multiple functions as input (...funcs)
// - Returns a function that takes a starting argument (arg)
// - Uses reduce to pass the result of each function to the next

// ➕ Function 1: Adds 2 to input
const add = (x) => x + 2;

// ✖️ Function 2: Multiplies input by 3
const multiply = (x) => x * 3;

// 🔧 Compose functions: First add, then multiply
const process = flow(add, multiply);

// 🧪 Test the composed function
console.log(process(5)); // Output: (5 + 2) * 3 = 21 ✅

Problem Statement

✅ Output Explanation:

  1. add(5) ➡️ 7
  2. multiply(7) ➡️ 21
  3. So process(5) gives 21.

🔍 Why Use flow?

  • It's a cleaner way to compose multiple functions.
  • Similar to lodash.flow or Ramda.pipe.
  • Encourages functional programming in JavaScript.

3️⃣ Debounce Polyfill + call, apply, bind usage

🧠 Expect to explain your approach, closure usage, and execution throttling logic.

💡 Round 3: System Design

1️⃣ A/B Testing — How Does It Work in the Frontend?

🧪 Core Concepts:

  • Split users into control & variant groups
  • Use feature flags to toggle UI dynamically
  • Track metrics: CTR, conversion, engagement

🛠️ Tools discussed: Google Optimize, Optimizely, VWO

2️⃣ Optimize Large Data Tables (Trillions of Records)

Strategies:

  • 🚀 Virtualized Rendering with react-virtualized or react-window
  • 🧠 Pagination, Lazy Loading, and infinite scroll
  • 💾 Use IndexedDB, localStorage, and intelligent caching
🔥 Performance tuning is critical in enterprise dashboards and analytics UIs.

💡 Round 4: Machine Coding

🧱 Task:

  • Build a NavBar with a user list.
  • On clicking a user:
    • Remove them from the list
    • Show their details in a side panel
  • Optimize re-renders using React.memo, useCallback

🧠 Focus Areas:

  • Component reusability & structure
  • Optimizing renders with React hooks
  • UI state management using useState or useReducer
🔄 The interviewer appreciated a clean folder structure and well-separated logic for state, UI, and event handling.

💡 Round 5: Hiring Manager

Questions Asked:

  • 🧠 “Tell me something about yourself that’s not in your resume.”
  • 💬 “Why did you choose engineering?”
  • 🔄 “Why did you switch jobs every 2 years?”
  • 🧭 “What do you expect from this role and company?”

🎯 Use the STAR Method (Situation, Task, Action, Result) for structured and impactful answers.

🚀 Key Takeaways & Tips

✅ DSA & JavaScript Core — Recursion, Closure, Event Loop
✅ System Design Knowledge — A/B Testing, Data Handling, Rendering
✅ React & Real-World Coding — Build & optimize UI components
✅ Behavioral Prep — Be self-aware and communicate your growth story

🎯 Final Thoughts

The Sense interview process was well-structured and technical. It tested my problem-solving mindset, UI architecture thinking, and hands-on coding ability. If you’re preparing for a modern frontend engineering role, this kind of multi-dimensional preparation is essential.

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💡 Tips to Crack the Sense Frontend Interview

✅ Understand the Interview Format:
Sense evaluates candidates holistically — from JavaScript fundamentals to large-scale frontend architecture. Prepare accordingly.

✅ Master Core JavaScript Concepts:
Closures, event loop, hoisting, scope chain, and asynchronous patterns are must-know topics.

✅ Practice DSA in JavaScript:
Use platforms like LeetCode or GeeksforGeeks. Focus on recursion, string/array manipulation, binary search, and object-based problems.

✅ Build Real-World Components:
Projects like modals, dropdowns, carousels, infinite scrolls, and dynamic sidebars show strong problem-solving skills.

✅ Sharpen System Design Knowledge:
Learn how to design scalable, performant frontend apps. Understand concepts like SSR, CSR, CDN caching, and lazy loading.

✅ Mock Interviews & Pair Programming:
Simulate interviews with peers or mentors to get real-time feedback on communication, clarity, and code structure.

✅ Ace the Behavioral Round with STAR:
Prepare thoughtful answers using the STAR method — Situation, Task, Action, Result — for questions around team leadership, decision-making, and cultural fit.

🧠 JavaScript & Browser Fundamentals

  • Hoisting, Scope, Closures, Currying
  • Event Loop, Microtasks vs Macrotasks
  • Memory Management & Garbage Collection
  • Call, Apply, Bind
  • Debounce & Throttle
  • Polyfills (e.g., for map, bind)

⚛️ React & Frontend Frameworks

  • Functional Components & Hooks
  • Context API, useReducer, useMemo
  • React.memo, useCallback
  • Virtual DOM & Reconciliation
  • Code Splitting, Lazy Loading

📦 Frontend Architecture & System Design

  • SSR vs CSR
  • Component Communication Patterns
  • Feature Flags & A/B Testing
  • Optimizing Rendering (e.g., React Virtualized)
  • Error Boundaries, Suspense, SuspenseList

🧪 Testing & Tooling

  • Unit Testing with Jest, React Testing Library
  • Browser DevTools & Lighthouse Audits
  • Webpack, Vite, and Build Optimizations

🧩 Machine Coding Patterns

  • State Management Techniques
  • Side Panel, List Filtering, Modal UI Logic
  • Performance Optimization for Dynamic UIs

📢 Hashtags for Visibility

#FrontendInterview #JavaScriptInterview #ReactJS #SystemDesign #WebDevelop #MachineCoding #TechInterviews #SenseAI #LeadFrontendEngineer #DSAinJavaScript #InterviewTips #SoftwareEngineerLife #TechHiring #CodeNewbie #FrontendMasters #JSInterviewPrep #MachineCodingRound #LearnYard

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