Shailesh Parmar’s Post

Frontend interviews are no longer just about React. They’re about how deeply you understand JavaScript and the web. Here’s what modern frontend interviews actually cover 👇 🔹 JavaScript Core & Advanced • First-class functions • Execution context & call stack • Hoisting & Temporal Dead Zone (TDZ) • this (regular vs arrow functions) • Currying & pure vs impure functions • Debounce vs throttle • Shallow vs deep copy • undefined vs null, optional chaining, nullish coalescing • Garbage collection & memory management • Event loop, streams & backpressure • Performance pitfalls (e.g. object de-optimization) 🔹 Async & Architecture • Promises & async/await flow • Concurrency handling • Preventing starvation • Task scheduling & execution order 🔹 React & Frontend Fundamentals • JSX & reconciliation • Component lifecycle (actual phases) • Controlled vs uncontrolled components • Error boundaries • Event handling patterns • useEffect behavior & optimization 🔹 Next.js & Backend Awareness • Server-side handling • API methods (GET, POST, PUT, DELETE) • REST structure & optimization thinking 🔹 Problem Solving • Breaking problems step-by-step • Optimization thinking before coding • Handling edge cases 💡 The shift is clear: Frontend interviews are moving from “Can you build UI?” → “Do you understand systems?” If you’re preparing, don’t just focus on frameworks. Focus on how things work under the hood. Which area do you think is the hardest — JavaScript, React, or System Design? 👇 #Frontend #JavaScript #React #NextJS #CodingInterview #SoftwareEngineering

Frontend interviews are no longer just about React. They’re about how deeply you understand JavaScript and the web. Here’s what modern frontend interviews actually cover 👇 🔹 JavaScript Core & Advanced • First-class functions • Execution context & call stack • Hoisting & Temporal Dead Zone (TDZ) • this (regular vs arrow functions) • Currying & pure vs impure functions • Debounce vs throttle • Shallow vs deep copy • undefined vs null, optional chaining, nullish coalescing • Garbage collection & memory management • Event loop, streams & backpressure • Performance pitfalls (e.g. object de-optimization) 🔹 Async & Architecture • Promises & async/await flow • Concurrency handling • Preventing starvation • Task scheduling & execution order 🔹 React & Frontend Fundamentals • JSX & reconciliation • Component lifecycle (actual phases) • Controlled vs uncontrolled components • Error boundaries • Event handling patterns • useEffect behavior & optimization 🔹 Next.js & Backend Awareness • Server-side handling • API methods (GET, POST, PUT, DELETE) • REST structure & optimization thinking 🔹 Problem Solving • Breaking problems step-by-step • Optimization thinking before coding • Handling edge cases 💡 The shift is clear: Frontend interviews are moving from “Can you build UI?” → “Do you understand systems?” If you’re preparing, don’t just focus on frameworks. Focus on how things work under the hood. Which area do you think is the hardest — JavaScript, React, or System Design? 👇 #Frontend #JavaScript #React #NextJS #CodingInterview #SoftwareEngineering

🚀 Interview Experience – Frontend (React/JavaScript) | 🔹 Coding / Problem-Solving 1. A parent div with 3 child divs. You need to place first at bottom-left and second at bottom-middle and third one at bottom-right. 🔹 JS output-based questions: 🌞 (function () { try { throw new Error(); } catch (x) { var x = 1, y = 2; console.log(x); } console.log(x); console.log(y); })(); 🌞 console.log(0 || 1); //1 console.log(1 || 2); //0 console.log(0 && 1); //0 console.log(1 && 2); // 2 🌞 (function(){ var a = b = 3; })(); console.log(a); console.log(b); 🌞 Create a React component that allows a user to select a file and simulate an upload process. When the user clicks the upload button, display a progress bar that gradually fills from 0% to 100% and show the upload percentage. The progress bar should update dynamically using React state. 🔹 Core JavaScript Concepts 1. Currying (currying vs normal functions) 2. call, apply, bind – when to use 3. Event loop 4. Promises: Promise.all, Promise.allSettled, Promise.race 5. Debouncing vs Throttling 6. Sync vs Deferred execution 7. Object & Array Destructuring 8. Difference between for...of and for...in . 🔹 React Topics 1. Hooks 2. useState – async or sync? How it works internally 3. Error Boundaries 4. Redux / Redux Toolkit flow 🔹 HTML & CSS Fundamentals 1. Box Model 2. CSS Specificity 3. Pseudo-classes and Pseudo-elements 4. Accessibility. Responsive Design techniques 🔹 Testing - Writing test cases (basic understanding expected) 💡 Overall, the interview focused more on fundamentals + real-world implementation rather than just theory. Would love to hear if you've come across similar questions or patterns! 👇 #PersistentSystems #Frontend #JavaScript #ReactJS #WebDevelopment #InterviewExperience #CodingInterview #Learning #CareerGrowth

If you’re preparing for frontend interviews… Save this. Here are 30 questions every frontend developer should know 👇 𝗝𝗮𝘃𝗮𝗦𝗰𝗿𝗶𝗽𝘁 𝗖𝗼𝗿𝗲 (𝗙𝗼𝘂𝗻𝗱𝗮𝘁𝗶𝗼𝗻) 1. Explain this, call, apply, bind 2. Difference between var, let, const 3. Event loop (microtasks vs macrotasks) 4. Debounce vs throttle (implement both) 5. Closures with real-world use cases 6. Shallow vs deep copy 7. Promise.all vs allSettled vs race 8. How async/await works internally 9. Memory leaks in JavaScript 𝗥𝗲𝗮𝗰𝘁 / 𝗥𝗲𝗮𝗰𝘁 𝗡𝗮𝘁𝗶𝘃𝗲 10. Reconciliation and Virtual DOM 11. Controlled vs uncontrolled components 12. useEffect lifecycle traps 13. State lifting vs global state 14. Context vs Redux vs Zustand 15. Rendering optimization techniques 16. Why keys matter (and how bad keys break apps) 17. Handling large lists efficiently 18. Error boundaries and crash recovery 𝗣𝗲𝗿𝗳𝗼𝗿𝗺𝗮𝗻𝗰𝗲 (𝗗𝗶𝗳𝗳𝗲𝗿𝗲𝗻𝘁𝗶𝗮𝘁𝗼𝗿) 19. How to reduce Time to Interactive (TTI) 20. Code splitting strategies 21. Memoization pitfalls 22. Prevent unnecessary re-renders 23. Image optimization techniques 24. Web Vitals (what actually matters) 𝗙𝗿𝗼𝗻𝘁𝗲𝗻𝗱 𝗦𝘆𝘀𝘁𝗲𝗺 𝗗𝗲𝘀𝗶𝗴𝗻 (𝗦𝗲𝗻𝗶𝗼𝗿 𝗹𝗲𝘃𝗲𝗹) 25. Design a scalable dashboard 26. Infinite scroll for millions of items 27. Real-time updates architecture 28. Offline-first app design 29. Feature flag system 30. Role-based access control (RBAC) 💡 Most candidates don’t fail because they don’t know these. They fail because they can’t explain them clearly or connect them together. If you can confidently answer even 70% of these, you’re already ahead of most candidates. Which topic do you find the hardest — JavaScript, React, or System Design? 👇 #Frontend #JavaScript #React #CodingInterview #SoftwareEngineering #WebDevelopment

If you’re preparing for frontend interviews… Save this. Here are 30 questions every frontend developer should know 👇 𝗝𝗮𝘃𝗮𝗦𝗰𝗿𝗶𝗽𝘁 𝗖𝗼𝗿𝗲 (𝗙𝗼𝘂𝗻𝗱𝗮𝘁𝗶𝗼𝗻) 1. Explain this, call, apply, bind 2. Difference between var, let, const 3. Event loop (microtasks vs macrotasks) 4. Debounce vs throttle (implement both) 5. Closures with real-world use cases 6. Shallow vs deep copy 7. Promise.all vs allSettled vs race 8. How async/await works internally 9. Memory leaks in JavaScript 𝗥𝗲𝗮𝗰𝘁 / 𝗥𝗲𝗮𝗰𝘁 𝗡𝗮𝘁𝗶𝘃𝗲 10. Reconciliation and Virtual DOM 11. Controlled vs uncontrolled components 12. useEffect lifecycle traps 13. State lifting vs global state 14. Context vs Redux vs Zustand 15. Rendering optimization techniques 16. Why keys matter (and how bad keys break apps) 17. Handling large lists efficiently 18. Error boundaries and crash recovery 𝗣𝗲𝗿𝗳𝗼𝗿𝗺𝗮𝗻𝗰𝗲 (𝗗𝗶𝗳𝗳𝗲𝗿𝗲𝗻𝘁𝗶𝗮𝘁𝗼𝗿) 19. How to reduce Time to Interactive (TTI) 20. Code splitting strategies 21. Memoization pitfalls 22. Prevent unnecessary re-renders 23. Image optimization techniques 24. Web Vitals (what actually matters) 𝗙𝗿𝗼𝗻𝘁𝗲𝗻𝗱 𝗦𝘆𝘀𝘁𝗲𝗺 𝗗𝗲𝘀𝗶𝗴𝗻 (𝗦𝗲𝗻𝗶𝗼𝗿 𝗹𝗲𝘃𝗲𝗹) 25. Design a scalable dashboard 26. Infinite scroll for millions of items 27. Real-time updates architecture 28. Offline-first app design 29. Feature flag system 30. Role-based access control (RBAC) 💡 Most candidates don’t fail because they don’t know these. They fail because they can’t explain them clearly or connect them together. If you can confidently answer even 70% of these, you’re already ahead of most candidates. Which topic do you find the hardest — JavaScript, React, or System Design? 👇 #Frontend #JavaScript #React #CodingInterview #SoftwareEngineering #WebDevelopment

Recently attended an interesting frontend interview for a product-based project. Sharing some of the questions/topics discussed — might help others preparing 👇 🔹 React & Performance - How do you optimize React bundle size? (code splitting, lazy loading, tree shaking) - What are techniques to improve initial load time? 🔹 React Query - How does caching work in React Query? - Difference between stale time vs cache time - How would you handle refetching and background updates? 🔹 JavaScript Concepts - What is debouncing? Where have you used it in real projects? - Difference between debouncing and throttling 🔹 Redux - How do you handle error states in Redux? - Best practices for managing API errors globally 🔹 Accessibility (Important 🔥) - How do you build a website for specially-abled users? - What are ARIA roles and when do you use them? - How do you ensure keyboard navigation and screen reader support? 🔹 Scenario-Based - How would you design API error handling across the application? - What approach would you take to improve performance of a slow UI? 💡 Key takeaway: Interviews are focusing heavily on real-world scenarios, performance, and accessibility — not just theory. #frontend #reactjs #javascript #webdevelopment #interviewpreparation #redux #reactquery #accessibility

🚀 Day 8/30 – Frontend Interview Series 📌 What is Async/Await? async/await is a modern way to handle asynchronous operations in JavaScript. It makes your code look cleaner and easier to read compared to Promises and callbacks. 🔹 1. async Keyword Used before a function Always returns a Promise async function greet() { return "Hello"; } greet().then(console.log); // Hello 🔹 2. await Keyword Used inside async functions only Waits for a Promise to resolve async function fetchData() { let data = await Promise.resolve("Data received"); console.log(data); } fetchData(); 🔥 3. Example (Real-world API) async function getUser() { try { let response = await fetch("https://lnkd.in/dEvCbUij"); let data = await response.json(); console.log(data); } catch (error) { console.log("Error:", error); } } ⚡ Why use async/await? ✔ Cleaner code (no .then() chaining) ✔ Easier error handling (try...catch) ✔ Looks like synchronous code ✔ Better readability in large apps #JavaScript #WebDevelopment #Frontend #ReactJS #CodingJourney

𝗙𝗿𝗼𝗻𝘁𝗲𝗻𝗱 𝗜𝗻𝘁𝗲𝗿𝘃𝗶𝗲𝘄 𝗤𝘂𝗲𝘀𝘁𝗶𝗼𝗻𝘀 𝗧𝗵𝗮𝘁 𝗧𝗲𝘀𝘁 𝗥𝗲𝗮𝗹 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗲𝗿 𝗦𝗸𝗶𝗹𝗹𝘀 I recently gave a frontend technical interview and realized something important. Companies are no longer focusing on DSA puzzles for frontend roles. Instead, they test practical knowledge that real developers use every day. Here are some of the questions asked in my interview: 1️⃣ useOptimistic (React) How can you update the UI instantly before the API response arrives? 2️⃣ AbortController (JavaScript) How do you cancel API requests to avoid race conditions and memory leaks? 3️⃣ Synthetic Events (React) How does React handle events internally and how is it different from native DOM events? 4️⃣ Debouncing vs Throttling When should each be used in performance optimization? 5️⃣ Virtual DOM & Reconciliation How does React efficiently update the UI? These questions focus on real-world frontend development, not just theoretical coding problems. If you're preparing for frontend interviews, make sure you deeply understand these concepts. #FrontendDeveloper #ReactJS #JavaScript #WebDevelopment #FrontendInterview #ReactDeveloper #SoftwareEngineer #TechInterview #CodingInterview #FrontendEngineering #ReactHooks #WebPerformance #Programming #CodeWithGandhi 

🚀 Frontend / React Interview Roadmap (Optimized) 🗓️ Phase 1 (Week 1–2): JavaScript Strong Foundation Sabse important hai JavaScript. 70% interviews yahin se hote hain. Important Topics :->> 1. Execution Context 2. Hoisting 3. Scope (Block vs Function) 4. Closures 5. Event Loop 6. Call stack 7. Promise & Async/Await 8. Prototype 9. this keyword 10. Debounce & Throttle 11. Shallow vs Deep Copy ⚛️ Phase 2 (Week 3–4): React Deep Concepts Agar tum **React interview clear karna chahte ho to ye topics must hain. Core Topics:--> 1. Virtual DOM 2. Reconciliation 3. Rendering phases 4. Hooks lifecycle 5. Controlled vs Uncontrolled 6. Context API 7. Error Boundaries 8. Code Splitting 9. Lazy Loading ✨React Optimization :--> 1. React.memo 2. useMemo 3. useCallback 4. Lazy loading 5. Virtualization 6. Debouncing Follow: Nikhil Sharma #React #interview #interviewprepration #roadmap #follow #javascript #developer #community #bestway #optimization #Reactinterview #frontend #frontendinterview

🚀 Want to stand out in Frontend Interviews? Master these JavaScript performance fundamentals 👇 ⚡ 1. Memory Management Avoid global variables. Use Map, Set, and WeakMap to prevent memory leaks and improve efficiency. ⚡ 2. Event Delegation Attach fewer event listeners → better performance, especially for dynamic DOM elements. ⚡ 3. Async Done Right Leverage async/await & Promise.all() to handle parallel operations without blocking the event loop. ⚡ 4. Debounce & Throttle Control high-frequency events like scroll, resize, and input for smoother UX. ⚡ 5. Lazy Loading & Code Splitting Load only what’s needed → faster initial load, better performance. ⚡ 6. Reduce Reflows & Repaints Batch DOM updates and avoid unnecessary layout thrashing. ⚡ 7. Smart Caching Use memoization, API caching, localStorage, and IndexedDB to reduce redundant work. 💡 Pro Tip: Great frontend developers don’t just build features… They build fast, scalable, and optimized experiences. 🔥 If you're preparing for frontend interviews, this is your edge. #JavaScript #Frontend #WebPerformance #InterviewPrep #ReactJS #CodingTips #SoftwareEngineering #TechCareers #100DaysOfCode