Harsh Marthak’s Post

Preparing for a Mid Level React Interview? Start with these questions: => How does React’s rendering process work? => What causes unnecessary re renders and how do you prevent them? => What’s the difference between state and props? => When should you lift state up? => How do you manage complex state in an application? => When would you use useState vs useReducer? => What are hooks, and why were they introduced? => How do useEffect dependencies work? => Have you ever faced an infinite re render issue? How did you fix it? => What is memoization in React? => When would you use React.memo, useMemo, and useCallback? => How do you handle API calls in React? => How do you manage loading, error, and success states? => How do you structure a scalable React application? => How do you manage shared state across components? => Context API vs Redux, when would you use each? => How do you optimize performance in React apps? => What tools do you use to debug performance issues? => What are controlled vs uncontrolled components? => When would you use refs? => How do you handle forms and validations? => How do you secure a React application? => How do you test React components? => Tell me about a complex UI you built => How did you improve performance in a React app? => What was the hardest bug you fixed in React? #ReactJS #FrontendDevelopment #TechInterviews #JavaScript #WebDevelopment #Developers

Preparing for a Mid Level React Interview? Here’s another set of questions: => What is reconciliation in React and how does it work? => How does React decide when to re render components? => What is the Virtual DOM and how is it different from the real DOM? => How does it improve performance? => What are keys in React and why are they important? => What issues can arise from using index as a key? => What is prop drilling and how do you avoid it? => What are better alternatives? => How do you handle side effects in React applications? => What are common mistakes with useEffect? => What is code splitting and how do you implement it in React? => When should you use lazy loading? => What are custom hooks? => How do you design reusable hooks? => What is the difference between controlled and uncontrolled side effects? => How do you manage cleanup in components? => How do you handle error boundaries in React? => What are their limitations? => What is hydration in React? => When does it matter? => How do you manage forms in large scale applications? => What libraries or approaches would you use? => What is the difference between client side rendering and server side rendering? => What are the trade offs? => How do you optimize bundle size in a React app? => What tools would you use to analyze it? => What are common performance bottlenecks in React apps? => How do you identify and fix them? => How do you manage state synchronization between multiple components? => What challenges have you faced? => How do you handle race conditions in API calls in React? => How do you cancel stale requests? => How do you structure reusable and maintainable component libraries? => What patterns do you follow? #ReactJS #FrontendDevelopment #TechInterviews #JavaScript #WebDevelopment #Developers

Day 2 of Interview Prep Series 👇 ❓ Virtual DOM vs Real DOM — what’s the actual difference? Almost every React developer has heard this… But very few can explain it clearly in interviews. 💭 Try answering before scrolling 👇 . . . ✅ Real DOM • Direct representation of UI in the browser • Updating it is slow (re-renders entire tree) • Every change impacts performance ✅ Virtual DOM • A lightweight copy of the Real DOM • React updates this first • Uses a diffing algorithm to update only what changed 💡 In simple terms: Virtual DOM = smart updates Real DOM = direct updates That’s why React apps feel faster ⚡ 👉 Follow-up: Can you explain this with a real-world example? (That’s what actually impresses in interviews 👀) #Day2 #ReactJS #InterviewPrep #Frontend #Developers #Braintech #Learning

🚀 Top 50 React Interview Questions – Must Prepare! 🔹 Preparing for a React interview? Focus on the fundamentals + real-world concepts: • What is React & how it works (Virtual DOM) • Functional vs Class components • Hooks (useState, useEffect, useContext) • Props vs State • Controlled vs Uncontrolled components • Lifecycle methods • Conditional rendering & lists • Forms & event handling 🔹 Level up with advanced topics recruiters love: • useMemo, useCallback & performance optimization • Context API vs Redux • Code splitting & lazy loading • Custom hooks • Error boundaries • React Router & navigation • API handling (fetch/axios) • Testing basics (Jest) 🔹 Pro tip: Don’t just memorize—build projects! • Create real apps • Explain your decisions • Be confident with debugging 💡 Master these, and you’re interview-ready! Source:- Respected owner ✨ Follow Asif Ali Quraishi ♞for web dev insights. #ReactJS #WebDevelopment #FrontendDeveloper #CodingInterview #JavaScript

🚀 Top 50 React Interview Questions – Must Prepare! 🔹 Preparing for a React interview? Focus on the fundamentals + real-world concepts: • What is React & how it works (Virtual DOM) • Functional vs Class components • Hooks (useState, useEffect, useContext) • Props vs State • Controlled vs Uncontrolled components • Lifecycle methods • Conditional rendering & lists • Forms & event handling 🔹 Level up with advanced topics recruiters love: • useMemo, useCallback & performance optimization • Context API vs Redux • Code splitting & lazy loading • Custom hooks • Error boundaries • React Router & navigation • API handling (fetch/axios) • Testing basics (Jest) 🔹 Pro tip: Don’t just memorize—build projects! • Create real apps • Explain your decisions • Be confident with debugging 💡 Master these, and you’re interview-ready! Source:- Respected owner ✨ Learn more from w3schools.com ✨ #ReactJS #WebDevelopment #FrontendDeveloper #CodingInterview #JavaScript

When I see such great posts on my timeline, I can't help but share them. If you are interested in React, you should definitely check it out. Even if you've already mastered React, it's good to revise and achieve next levels of your React Mastery.

Common React Native Interview Questions 🚀 If you're preparing for a React Native interview, these are some questions you’ll likely face: 🔹 What is React Native? Explain cross-platform development and how React Native works. 🔹 Difference between React and React Native? Web vs Mobile applications. 🔹 What are Props and State? How data flows in React Native components. 🔹 What is FlatList and why use it? Efficient rendering for large lists. 🔹 What is useEffect? Handling side effects like API calls. 🔹 How do you optimize performance in React Native? Memoization, FlatList, avoiding re-renders. 🔹 What is Flexbox in React Native? Layout system used for UI design. 🔹 How do you handle API calls? Fetch / Axios usage. These are some basic questions that appear frequently in React Native interviews. Tip: Focus on fundamentals — they matter the most. Still learning and improving every day 🚀 What was the toughest React Native interview question you faced? #ReactNative #InterviewPreparation #FrontendDeveloper #SoftwareEngineer #DeveloperTips #CodingInterview

🚀 React Interview Question: What are Error Boundaries in React? 💡 Error Boundaries: Error Boundaries are components that catch errors in the UI and prevent the app from crashing. Instead of showing a broken screen, they display a fallback UI like “Something went wrong.” 🔹 Why use them? - prevent full app crash - show user-friendly error message - improve user experience 🔹 Example: class ErrorBoundary extends React.Component { state = { hasError: false }; static getDerivedStateFromError() { return { hasError: true }; } render() { if (this.state.hasError) { return <h1>Something went wrong </h1>; } return this.props.children; } } 🔹Note: Error Boundaries only work in class components ✅ If you are preparing for ReactJs interview, save this for your next interview! Follow Tarun Kumar for tech content, coding tips, and interview prep 🚀 #React #JavaScript #InterviewPrep #Frontend #Coding

React interviews be like: “Let’s start with something simple…” 😄 5 minutes later… Explain reconciliation. Why is useEffect running twice? How does React decide to re-render? What are keys and why did your app just break? If you’re preparing, here are the React topics that show up everywhere 👇 🧠 The “I thought I knew this” topics • Virtual DOM & reconciliation • Component re-rendering logic • Keys (and why bad keys cause chaos) • Controlled vs uncontrolled components ⚡ Hooks (favorite interview weapon) • useState batching & updates • useEffect (dependencies, cleanup, infinite loops 😅) • useMemo vs useCallback • When NOT to use hooks 🚀 Performance (where candidates struggle) • Preventing unnecessary re-renders • React.memo and memoization • Handling large lists (virtualization) • Code splitting & lazy loading 🏗 Architecture & State Management • Lifting state vs global state • Context vs Redux vs Zustand • Component design patterns • Separation of concerns 🔥 Real-world thinking • How would you optimize a slow React app? • How do you structure a scalable project? • How do you handle API states (loading/error/success)? 💡 Reality check: Everyone knows how to use React. Very few understand how React works. That’s exactly what interviews test. So next time someone says “Let’s start with something simple…” Be ready 😄 Which React topic surprised you the most in interviews? 👇 #React #Frontend #JavaScript #CodingInterview #SoftwareEngineering #WebDevelopment

💡 React Interview Questions I Prepared as a Developer While preparing for interviews, I compiled a list of important React questions into a PDF 📄 Instead of keeping it to myself, I thought of sharing a quick summary here 👇 🔹 What is React? A JavaScript library for building UI using reusable components. 🔹 What is Virtual DOM? React creates a virtual copy of the DOM and updates only the changed parts → faster performance. 🔹 What are Hooks? Functions like "useState", "useEffect" that let you use state and lifecycle features in functional components. 🔹 What is State vs Props? State → managed inside component Props → passed from parent to child 🔹 What is useEffect? Used for side effects like API calls, subscriptions, timers. 🔹 What is conditional rendering? Displaying UI based on conditions (if/else, ternary). 🔹 What is key in React? Unique identifier for list items → helps React optimize rendering. 🔹 What is lifting state up? Sharing state between components by moving it to a common parent. --- 📄 I’ve attached my full PDF with more questions and explanations. Feel free to check it out! #ReactJS #FrontendDevelopment #WebDevelopment #MERNStack #InterviewPrep #LearnToCode