React Lifecycle Methods: Mounting, Updating, Unmounting

🚀 React Interview Question Breakdown – Can You Spot the Issues? Recently, I came across some interesting React interview questions focused on debugging and code optimization. Sharing them here 👇 🔍 Question 1: Find the issues and fix them const items = useSelector(state => state.items); const [filtered, setFiltered] = useState(items); useEffect(() => { setFiltered(items.filter(i => i.name.includes(search))); }, []); 🔍 Question 2: Find the issues and fix them const handleLike = async () => { const newCount = likes + 1; setLikes(newCount); await api.updateLikes(newCount); if (condition) { setLikes(likes + 1); // Review point } }; #ReactJS #FrontendDevelopment #JavaScript #WebDevelopment #InterviewQuestions #ReactHooks

🚀 3 Tricky React Interview Questions Asked in Top Companies These are NOT your typical “what is useState?” questions. These are the ones that actually test your real understanding of React 👇 ⸻ 1️⃣ Why does a component re-render even with React.memo? You wrapped a child with React.memo. Props look the same… but it still re-renders. 👉 Reason: React.memo does shallow comparison 👉 Objects, arrays, and functions create new references every render 💡 Fix: Use useMemo / useCallback to stabilize references ⸻ 2️⃣ Why is useEffect running twice in development? You used an empty dependency array, still it runs twice 🤯 👉 This is NOT a bug 👉 It’s React Strict Mode (React 18+) 💡 React intentionally mounts → unmounts → mounts again to detect side effects & bugs early ✅ Happens only in development, not in production ⸻ 3️⃣ Why is state not updating inside async functions? You update state, but inside setTimeout or async code it still shows the old value 😵 👉 Reason: Stale closures (JavaScript behavior) 💡 Fix: ✔️ Use functional updates → setState(prev => prev + 1) ✔️ Or useRef for latest value ⸻ 🎯 Interview Tip: Use these keywords to stand out: ✔️ Shallow comparison ✔️ Reference equality ✔️ Strict Mode behavior ✔️ Stale closures #ReactJS #FrontendDeveloper #WebDevelopment #JavaScript #InterviewPrep #ReactInterview #Coding #interview #prepration #Developer

If you’re preparing for React interviews, don’t skip these 👇 ⚡ useEffect (most misunderstood hook) – dependency array – cleanup function – when NOT to use it ⚡ State management – useState vs useReducer – when to lift state up ⚡ Re-rendering – why components re-render – how to prevent unnecessary renders ⚡ Performance basics – memoization (React.memo, useMemo, useCallback) – lazy loading ⚡ API handling – loading states – error handling – avoiding multiple calls Most interviews don’t ask advanced tricks. They test how well you understand basics. 💡 Go deep, not wide. 💬 Which topic do you find most confusing? #ReactJS #FrontendDevelopment #JavaScript #WebDevelopment #CodingInterview #GauravTiwari

Frontend Interview Experience – A Small but Interesting Redux Debate Recently attended a frontend interview where the discussion covered HTML, CSS, JavaScript, React, GraphQL, and Microfrontends. During the React round, I was asked about the core pillars of Redux. I explained: • Store – holds the application state • Actions – plain JavaScript objects describing what happened • Reducers – pure functions that return the new state • Dispatch – sends actions to the store • Selectors – used to read data from the store Then came an interesting moment The interviewer mentioned that "Actions are functions, not objects." I respectfully shared my understanding that: In Redux, an Action is a plain JavaScript object with a mandatory type field. After the interview, I double-checked — and yes, Redux defines actions as plain objects. The likely confusion: What the interviewer referred to was Action Creators, which are functions that return action objects. Example: const addTodo = (text) => ({ type: "ADD_TODO", payload: text }); Key takeaway: • Action = Object • Action Creator = Function 🎯 Interviews are not just about right or wrong — they’re about clarity of concepts and communication. Curious to know — have you ever faced a situation where both perspectives were technically correct but misunderstood in interviews? #Frontend #React #Redux #JavaScript #InterviewExperience #Learning

Great resource for anyone preparing for React interviews. I’m currently learning and this gives me a clear idea of what to focus on next.

Interview preparation isn't just for beginners. Even as a Lead, I find that revisiting the core internals—like the React Fiber architecture and Memoization patterns—is essential for building high-performance UIs at scale. This guide looks like a fantastic structured roadmap for anyone in the React ecosystem. As I always say to beginners: 'If you can't explain it simply, you don't understand it well enough.' Checking this out today! 💻🔥 #ReactJS #FrontendEngineering #TechLeadership #InterviewPrep

💡 Frontend Interview Questions I Found Interesting While preparing for frontend interviews, I came across some questions that really test your understanding beyond basics: JavaScript: 1️⃣ What is the output and why? console.log([] == ![]); 2️⃣ Explain how the event loop works in JavaScript. 3️⃣ What’s the difference between == and ===? When can == be tricky? 4️⃣ How do closures work in real-world scenarios? React: 5️⃣ What causes unnecessary re-renders in React? How do you optimize them? 6️⃣ Difference between useEffect and useLayoutEffect? 7️⃣ How does React’s reconciliation algorithm work? 8️⃣ How would you design state management for a large-scale application? 💭 These questions made me realize: Knowing syntax is not enough — understanding behavior and thinking deeply is what matters in interviews. Still learning and improving every day 🚀 #javascript #reactjs #frontenddevelopment #interviewprep #webdevelopment

❓ React Interview Question: useCallback vs useMemo in React When building React applications, unnecessary re-renders and expensive computations can impact performance. This is where hooks like useCallback and useMemo help optimize rendering efficiency. 🔹 useCallback Used to memoize a function, so it doesn’t get recreated on every render. This is especially useful when passing functions to child components to prevent unwanted re-renders. 🔹 useMemo Used to memoize a computed value, avoiding expensive recalculations unless dependencies change. 👉 Follow Tarun Kumar for tech content, coding tips, and interview prep 🚀 #ReactJS #ReactHooks #ReactInterviewQuestions #FrontendDevelopment #JavaScript #WebDevelopment #CodingInterview #SoftwareEngineering #TechTips #LearnToCode

🔥 Frontend Interview Questions You MUST Know 1️⃣ What are the component lifecycle methods in class components and how are they handled in functional components? 2️⃣ Walk me through controlled vs uncontrolled components in React. 3️⃣ Can you explain event delegation in JavaScript with an example? 4️⃣ What are closures in JavaScript? What are their advantages and disadvantages? 5️⃣ How do memory leaks happen in frontend applications? How can you prevent them? 6️⃣ What is garbage collection in JavaScript? Can you explain the Mark and Sweep algorithm? Comment your answers below or save this post to revise later before your next interview! Let’s learn together 🚀 #FrontendDeveloper #JavaScript #ReactJS #InterviewPreparation #FrontendInterview #WebDevelopment #Frontend #ReactDeveloper