React Hooks: useDeferredValue Explained

React Interview Question: What is useTransition in React? Answer: useTransition allows developers to mark state updates as non-urgent. Example: 𝘤𝘰𝘯𝘴𝘵 [𝘪𝘴𝘗𝘦𝘯𝘥𝘪𝘯𝘨, 𝘴𝘵𝘢𝘳𝘵𝘛𝘳𝘢𝘯𝘴𝘪𝘵𝘪𝘰𝘯] = 𝘶𝘴𝘦𝘛𝘳𝘢𝘯𝘴𝘪𝘵𝘪𝘰𝘯() 𝘴𝘵𝘢𝘳𝘵𝘛𝘳𝘢𝘯𝘴𝘪𝘵𝘪𝘰𝘯(() => {  𝘴𝘦𝘵𝘚𝘦𝘢𝘳𝘤𝘩𝘙𝘦𝘴𝘶𝘭𝘵𝘴(𝘥𝘢𝘵𝘢) }) Explanation: React prioritizes urgent updates like user typing while processing non-urgent updates in the background. Follow-up Interview Question: When should useTransition be used? Answer: When updating large UI elements such as: 1. search results 2. large lists 3. heavy rendering components #reactjs #ConcurrentRendering #ReactHooks #WebPerformance

In almost every React interview I’ve attended, one question always shows up… “Explain React lifecycle methods.” React components go through three phases: → Mounting (component is created and inserted into the DOM) Important methods: • constructor() → initialize state • render() → returns the UI • componentDidMount() → best place for API calls or data fetching → Updating (when props or state change) Important methods: • shouldComponentUpdate() → control re-renders for performance • render() → updates the UI • componentDidUpdate() → run logic after updates → Unmounting (component is removed from the DOM) Important method: • componentWillUnmount() → cleanup tasks like removing event listeners or cancelling timers Understanding lifecycle methods tells interviewers one important thing: You don’t just use React… You understand how it behaves behind the scenes. #React #FrontendDevelopment #JavaScript #TechInterviews #WebDevelopment

🚀 React Interview Series | Day 13: What are Hooks in React? The Interview Question: Video Explanation: https://lnkd.in/dfUs4JpB 👉 “What are Hooks in React?” 💡 Simple Answer: Hooks are special functions that allow you to 'hook into' React’s internal state and lifecycle features from functional components. 🧠 Before Hooks: We used class components More complex code 😵💫 🔥 After Hooks: Everything in functional components Cleaner & easier to manage ✅ 📦 Most Common Hooks: 👉 useState → to store and update data 👉 useEffect → to run logic when something happens ⚡ When to use Hooks? When you need to store user input or dynamic data When you need to call an API When something should happen on load/update When building interactive UI 🎯 Why use Hooks? Cleaner and shorter code ✅ No need for class components Easy to reuse logic (custom hooks) Makes code more readable & maintainable ⚡ Example: const [count, setCount] = useState(0); useEffect(() => { console.log("Component loaded"); }, []); 🔥 Pro Tip: Don’t just memorize hooks — understand when and why to use them in real projects 💬 Tomorrow Question: What is jsx, babel, webpack #reactjs #frontenddevelopment #javascript #webdevelopment #reacthooks #codinginterview #learnreact

React Interview Question: How does React handle state updates internally and why are they asynchronous? Answer: React batches state updates to improve performance and avoid unnecessary re-renders. Example: 𝘴𝘦𝘵𝘊𝘰𝘶𝘯𝘵(𝘤𝘰𝘶𝘯𝘵 + 1) 𝘴𝘦𝘵𝘊𝘰𝘶𝘯𝘵(𝘤𝘰𝘶𝘯𝘵 + 1) This does not always increment twice because React may batch updates. Correct approach: 𝘴𝘦𝘵𝘊𝘰𝘶𝘯𝘵(𝘱𝘳𝘦𝘷 => 𝘱𝘳𝘦𝘷 + 1) 𝘴𝘦𝘵𝘊𝘰𝘶𝘯𝘵(𝘱𝘳𝘦𝘷 => 𝘱𝘳𝘦𝘷 + 1) Explanation: React queues updates and processes them together to: • minimize re-renders • improve performance • keep UI consistent This behavior is more prominent in Concurrent Rendering. Follow-up Question: How does batching behavior differ between React 17 and React 18? #reactjs #InterviewPreparation #FrontendDevelopment #SoftwareEngineering

🚀 React Interview Series | Day 2: Elements vs Components I once saw a candidate get stuck on this question for 10 minutes in an interview. Don’t let that be you. React Element It’s just a plain JavaScript object. If you console.log(<div />), you’ll see an object describing the DOM node. It’s immutable — basically a receipt of what you want on the UI. React Component This is the factory. A function or class that returns React elements based on props and state. Why This Matters If you know an Element is just an object, you understand why React’s diffing is fast. ✔ Comparing objects → cheap ❌ Re-rendering a full DOM tree → expensive #React #JavaScript #WebDevelopment #Frontend #ReactJS #ReactInterviewSeries #day2

🚨 React Interview Question What will be the output? const [count, setCount] = useState(0); const handleClick = () => { setCount(count + 1); setCount(count + 1); }; console.log(count); ❓ After clicking the button once, what will be the value of count? A️ )0 B️ )1 C️ )2 D️ ) Error 👇 Comment your answer below! #ReactJS #FrontendDeveloper #JavaScript #CodingInterview #ReactInterview

⚛️ React Interview Question Why can’t we use async/await directly inside useEffect? At first, it feels natural to write this: useEffect(async () => { const data = await fetchData(); setData(data); }, []); But React will complain. Because useEffect expects either: • nothing • or a cleanup function Example of cleanup: - useEffect(() => { const id = setInterval(() => { console.log("running..."); }, 1000); return () => clearInterval(id); }, []); When you make the effect function async, it returns a Promise, not a cleanup function. And React doesn’t know how to handle that. The Correct Pattern Define an async function inside the effect: useEffect(() => { const fetchData = async () => { const data = await getUsers(); setUsers(data); }; fetchData(); }, []); Small detail. Understanding why it happens is more important than memorizing the fix. #ReactJS #FrontendInterview #JavaScript #WebDevelopment #TechCareers

💡React Interview Question💡 Why to use Redux toolkit instead of core redux? Answer: Redux toolkit is preferred instead of core redux for new React applications, because it helps to avoid writing boilerplate code. Also we get the following benefits with redux toolkit: ✅ No need to manually add redux devtool configuration in the code, as the configuration comes in-built with the redux toolkit. ✅ No need to separately install the redux-thunk package to make async API calls, because it also comes in-built with the redux toolkit. ✅ Redux toolkit helps to avoid complex manipulation and write less code So, If you have a redux state like this: const initialState = { profile: { name: 'Mike', location: { state: 'NY', city: 'NY' } } } then If you want to update the city name to 'Amsterdam' using 𝗰𝗼𝗿𝗲 𝗿𝗲𝗱𝘂𝘅, we need to write reducer code like this: const userReducer = (state = initialState, action) => { ... case UPDATE_PROFILE_CITY: return { ...state, profile: { ...state.profile, location: { ...state.profile.location, city: action.payload, }, }, }; ... } However, with the redux toolkit you can write code to update in a single line like this: const usersSlice = createSlice({ ... reducers: { updateProfileCity(state, action) { state .profile .location .city = action.payload; }, } }); So with redux toolkit, you don't need to return a new state object with modifications, instead, you can directly update any property of the state because createSlice uses the immer.js library behind the scenes to achieve the immutability. 𝗙𝗼𝗿 𝗺𝗼𝗿𝗲 𝘀𝘂𝗰𝗵 𝘂𝘀𝗲𝗳𝘂𝗹 𝗰𝗼𝗻𝘁𝗲𝗻𝘁, 𝗱𝗼𝗻'𝘁 𝗳𝗼𝗿𝗴𝗲𝘁 𝘁𝗼 𝗳𝗼𝗹𝗹𝗼𝘄 𝗺𝗲. #javascript #reactjs #redux #interviewquestions #webdevelopment

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