Code Splitting in React Improves Performance

🚀 React Interview Question: What is React Strict Mode? 💡 React Strict Mode is a development tool in React that helps you identify potential problems in your application during development. It runs only in development mode and does not impact production. 🔹 Why do we need it? Sometimes in development: - you might write unsafe code - use deprecated methods - create unintended side effects Strict Mode helps catch these issues early before they reach production. 🔹 Example: React.StrictMode wraps your app and enables extra checks import React from "react"; import ReactDOM from "react-dom/client"; import App from "./App"; const root = ReactDOM.createRoot(document.getElementById("root")); root.render( <React.StrictMode> <App /> </React.StrictMode> ); 🔹 Side Effect Example: import React, { useEffect } from "react"; function App() { useEffect(() => { console.log("API called"); }, []); return <h1>Hello World</h1>; } export default App; here, "API called" may log twice in development, because Strict Mode intentionally runs components twice to detect side effects. 🔹 Benefits of using React Strict Mode - detects unsafe lifecycle methods - identifies unexpected side effects - warns about deprecated APIs - helps find bugs in state and hooks - encourages clean and maintainable code 🔹 Use case: When building scalable apps, you want early warnings for bad practices. Strict Mode helps ensure your code is future-ready. Connect/Follow Tarun Kumar for more tech content and interview prep 🚀 #React #JavaScript #Frontend #WebDevelopment #Coding #SoftwareEngineering #InterviewPrep

🚀 React Interview Question:What is forwardRef() in React used for? 💡 What is forwardRef()? forwardRef is a React utility that allows a parent component to pass a ref through a child component, enabling direct access to the child’s DOM node or instance. This is especially useful when the child is wrapped by other components and doesn’t expose the ref by default. - by default, refs don’t work on custom components - forwardRef makes it possible 🔹 Why do we need it? Sometimes we need direct DOM access for: - focusing an input - triggering animations - integrating with third-party libraries 🔹 Example: import React, { forwardRef } from "react"; const Input = forwardRef((props, ref) => { return <input ref={ref} {...props} />; }); export default function App() { const inputRef = React.useRef(); return ( <> <Input ref={inputRef} /> <button onClick={() => inputRef.current.focus()}> Focus Input </button> </> ); } 🔹 When should you use forwardRef()? - when parent needs direct access to child DOM - for reusable component libraries - for focus, scroll, or animations - when integrating non-React code Follow Tarun Kumar for tech content, coding tips, and interview prep #React #ReactJS #FrontendDevelopment #JavaScript #WebDevelopment #CodingInterview #InterviewPreparation #SoftwareEngineering #TechLearning #Programming

React Interview Question: What is Concurrent Mode in React & Why It Matters? React apps may become slow during heavy updates since all rendering happens on a single thread. To solve this, React 18 introduces Concurrent Features (previously experimented as Concurrent Mode). 🔹 What is Concurrent Mode? Concurrent Features allow React to pause, resume, and prioritize rendering work as needed. Instead of blocking the UI, React becomes more flexible and responsive. 🔹 How Concurrent Mode improves performance? Interruptible rendering - React can pause rendering work in between and resume later instead of blocking the main thread. Incremental rendering (breaking work into chunks) - Large rendering tasks are split into smaller units so the browser gets time to handle user interactions. Priority-based scheduling - Updates are assigned priorities (e.g., user input > data rendering), ensuring critical work runs first. Avoiding unnecessary work - React can discard outdated renders if newer updates come in, preventing wasted computation. 🔹 Key features behind it  useTransition ( Mark updates as non-urgent )  useDeferredValue ( Delay rendering of less important data )  Automatic batching ( Fewer re-renders — a React 18 improvement, works independently of concurrent features ) 🔹 Example const [isPending, startTransition] = useTransition(); const handleChange = (e) => {  const value = e.target.value;  setInput(value); // urgent update  startTransition(() => {   setFilteredList(filterItems(value)); // non-urgent  }); }; 🔹Conclusion Concurrent Features in React 18 make apps faster, smoother, and more responsive by scheduling and prioritizing rendering tasks efficiently. Connect/Follow Tarun Kumar for more tech content and interview prep #React #Frontend #WebDevelopment #JavaScript #Performance #SoftwareEngineering

🚀 React Interview Question: What is React Suspense? 💡 React Suspense is a feature that allows React to wait for something (like a component or data) before rendering it, and show a fallback UI (like a loader) in the meantime. Suspense lets React pause rendering and display a loading screen until everything is ready. 🔹 Example: import React, { Suspense, lazy } from "react"; const MyComponent = lazy(() => import("./MyComponent")); function App() { return ( <Suspense fallback={<h1>Loading...</h1>}> <MyComponent /> </Suspense> ); } 🔹 How it works: - lazy() loads the component asynchronously - suspense wraps the component - fallback shows a loader while loading 🔹 Why use Suspense? - cleaner code (no manual loading state everywhere) - better user experience - built for modern async React apps follow Tarun Kumar for more tech content and interview prep #ReactJS #FrontendDevelopment #JavaScript #WebDevelopment #CodingInterview #SoftwareEngineering #TechContent #DeveloperTips

React Interview Question: How does React Router work, and how do you implement dynamic routing? 🔹 How React Router works React Router is a client-side routing library that enables navigation between components without reloading the page. Instead of requesting a new HTML page from the server, React Router: - listens to URL changes - matches the URL with a defined route - renders the corresponding component - updates UI without full page refresh This makes React apps fast and seamless. 🔹 What is Dynamic Routing? Dynamic routing means routes are not fixed, they change based on parameters in the URL. Example of Dynamic Routing: /user/1 /user/2 /product/101 Here, 1, 2, 101 are dynamic values. 🔹 How to implement Dynamic Routing in React We use route parameters using : (colon syntax). Example: import { BrowserRouter, Routes, Route, useParams } from "react-router-dom"; function User() { const { id } = useParams(); return <h2>User ID: {id}</h2>; } function App() { return ( <BrowserRouter> <Routes> <Route path="/" element={<h1>Home</h1>} /> <Route path="/user/:id" element={<User />} /> </Routes> </BrowserRouter> ); } 🔹 How it works internally - user visits /user/5 - react Router matches /user/:id - extracts id = 5 - passes it to component via useParams() - component renders dynamic data 🔹 Real-world use cases - user profile pages - product detail pages - order details - blog post pages 🔹Conclusion: React Router enables SPA navigation, and dynamic routing allows you to build flexible, data-driven pages using URL parameters. Connect/Follow Tarun Kumar for more tech content and interview prep #ReactJS #ReactRouter #FrontendDevelopment #JavaScript

Some of the most commonly asked questions in React interviews in 2026 that might help fellow developers preparing for similar roles. 💡 🔍 Key React Interview Questions (2026 Trends) 1️⃣ What are the differences between Client Components and Server Components in React? 2️⃣ Explain the React rendering lifecycle in functional components. 3️⃣ How does React Fiber architecture improve performance? 4️⃣ What are custom hooks and when should you create one? 5️⃣ Difference between useMemo, useCallback, and React.memo. 6️⃣ How does React handle reconciliation and the virtual DOM? 7️⃣ What are controlled vs uncontrolled components? 8️⃣ How would you optimize a React application experiencing unnecessary re-renders? 9️⃣ Explain state management approaches (Context API, Redux, Zustand, etc.). 🔟 What are React Server Components and how do they impact performance? ⚙️ Practical / Coding Round Topics • Build a searchable list with debouncing • Create a custom hook (e.g., useDebounce / useFetch) • Implement pagination or infinite scrolling • Optimize a component suffering from performance issues • Implement form validation in React 💬 Behavioral / System Thinking Questions • How do you structure a scalable React project? • How do you handle performance optimization in large React apps? • Explain a challenging bug you solved in production. ✨ Key Takeaway: Companies are increasingly focusing on React internals, performance optimization, hooks, and real-world architecture decisions, rather than just basic syntax. If you're preparing for a React Developer role in 2026, focus on: ✔ Hooks & custom hooks ✔ Performance optimization ✔ Modern React architecture ✔ Real-world problem solving Hope this helps someone preparing for their next opportunity! 🙌 #ReactJS #FrontendDevelopment #WebDevelopment #JavaScript #ReactDeveloper #FrontendEngineer #SoftwareEngineering #TechInterviews #InterviewPreparation #ProductBasedCompany #ReactHooks #Programming

🚀 React Interview Question: What does Re-rendering mean in React? 💡Re-rendering in React means updating the UI when a component’s data changes. 🔹 Key Idea: When state or props change, React re-runs the component function and updates the UI to reflect the latest data. 🔹 Example: import React, { useState } from "react"; function Counter() { const [count, setCount] = useState(0); return ( <div> <p>Count: {count}</p> <button onClick={() => setCount(count + 1)}> Increment </button> </div> ); } Clicking the button updates the state --> React re-renders --> UI updates. 🔹 When does re-render happen? - state changes (useState) - props change - parent component re-renders 🔹 Note: React does NOT refresh the whole page — it efficiently updates only the changed parts using the Virtual DOM. Follow Tarun Kumar for more tech content and interview prep #ReactJS #FrontendDevelopment #JavaScript #WebDevelopment #CodingInterview #SoftwareEngineering #TechContent #DeveloperTips

❓ React Interview Question: Difference between State and Props? 💡 What are Props? Props are inputs passed from parent to child components - They are read-only (immutable) - Used to make components reusable function Greeting(props) { return <h1>Hello {props.name}</h1>; } 💡 What is State? State is data managed inside a component - It can change over time (mutable) - Used for dynamic UI updates const [count, setCount] = useState(0); 💡 Key Differences props → Passed from parent, cannot be modified state → Managed inside component, can be updated props → Used for communication between components state → Used for handling dynamic data Follow Tarun Kumar for tech content, coding tips, and interview prep 🚀 #ReactJS #ReactInterview #FrontendInterview #JavaScript #CodingInterview #InterviewPrep #WebDevelopment #Developers #TechContent

🚀 Out-of-the-Box React Interview Series – Beyond Hooks & Props! Everyone asks about useState, useEffect, and lifecycle… But real-world React interviews dig deeper into how React actually behaves under the hood ⚛️ Let’s challenge your thinking with some unconventional React questions 👇 🔹 1. Why is this component re-rendering? const Child = ({ data }) => { console.log("Rendered"); return <div>{data.value}</div>; }; const Parent = () => { const data = { value: 1 }; return <Child data={data} />; }; 👉 Even without state change, why does Child re-render? 🔹 2. Can memoization fail here? const MemoChild = React.memo(({ obj }) => { console.log("Memo Rendered"); return <div>{obj.value}</div>; }); <MemoChild obj={{ value: 1 }} /> 👉 Why doesn’t React.memo help? What’s the fix? 🔹 3. Stale closure trap const [count, setCount] = useState(0); useEffect(() => { setInterval(() => { console.log(count); }, 1000); }, []); 👉 Why does it always log 0? How do you fix it properly? 🔹 4. Key prop mystery {items.map((item, index) => ( <Component key={index} value={item} /> ))} 👉 When does this break your UI in real-world apps? 🔹 5. State update illusion setCount(count + 1); setCount(count + 1); 👉 Why does count increase only once? 💬 These questions go beyond syntax. They test: ✔️ Rendering behavior & reconciliation ✔️ Referential equality ✔️ Hooks internals & closures ✔️ Performance optimization mindset 🔥 If you're targeting senior/frontend roles, mastering these patterns is a game changer. Follow for more in this Out-of-the-Box Interview Series ⚡ #reactjs #frontenddeveloper #webdevelopment #interviewquestions #reactinterview #javascript #codinginterview #softwareengineering #react #developers

🚀 React Interview Question: What is Lazy Loading in React? 💡 Lazy loading is a technique where components are loaded only when they are needed, instead of loading everything upfront. This helps improve performance and reduces initial load time. 🔹 How it works: Instead of importing components normally: import Dashboard from "./Dashboard"; You load them dynamically: const Dashboard = React.lazy(() => import("./Dashboard")); And wrap with Suspense: <Suspense fallback={Loading...}> 🔹 Why use Lazy Loading - faster initial page load - reduces bundle size - improves user experience 🔹 Real-world use case: Imagine a large app with multiple pages (Dashboard, Profile, Settings). Users don’t need all pages at once. - load only what the user visits. 🔹 Key Insight: - don’t load everything upfront. - load only when required. Connect/Follow Tarun Kumar for more tech content and interview prep 🚀 #ReactJS #Frontend #WebDevelopment #Performance #JavaScript #CodingInterview