useEffect Dependency Array Explained

⚛️ Top React Interview Questions Every Developer Should Prepare React is one of the most widely used libraries for building modern user interfaces. If you're preparing for a frontend or React developer interview, mastering the core concepts is essential. Here are some important React interview topics you should know: ✔ What is React and why is it used? ✔ Virtual DOM and how React updates the UI ✔ Functional Components vs Class Components ✔ React Hooks (useState, useEffect, useMemo, useCallback) ✔ Props vs State ✔ React Lifecycle Methods ✔ Controlled vs Uncontrolled Components ✔ Context API and when to use it ✔ React Performance Optimization ✔ Code Splitting and Lazy Loading ✔ Error Boundaries ✔ Custom Hooks ✔ Server-Side Rendering (SSR) --- Preparing these concepts will help you crack React interviews at product-based and service-based companies. Focus on core concepts, performance optimization, and real-world use cases. #ReactJS #FrontendDevelopment #WebDevelopment #JavaScript #ReactInterview #Programming #SoftwareDevelopment #CodingInterview #Developers #TechInterview #ReactDeveloper

❓ React Interview Question: What is useEffect? ✅ Answer: useEffect is a React Hook used to handle side effects in functional components. Side effects include operations like API calls, subscriptions, timers, and DOM updates. It runs after the component renders and can be controlled using a dependency array to decide when it should execute. 💡 Why we use useEffect? React components are meant to be pure, but real-world applications need to: --> fetch data from APIs --> set up event listeners --> work with timers useEffect allows us to perform these operations safely after rendering. #ReactJS #FrontendDevelopment #WebDevelopment #JavaScript #SoftwareEngineering #InterviewPreparation #CodingInterview

❓ 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

Just finished building an React JSX & Rendering Interview Guide covering basic to advanced to expert concepts. If you are preparing for React interviews, this guide can help you revise the topics that interviewers actually explore, including: • JSX fundamentals • Rendering in React • Conditional rendering • Lists and keys • Reconciliation • Virtual DOM • Component rendering behavior • Performance optimization • Memoization and re-render control • SSR, hydration, and advanced rendering concepts I created it to make React preparation more structured, practical, and interview-focused instead of just memorizing random questions. React is easy to start with, but truly understanding how rendering works is what helps you write better UI, debug faster, and perform well in interviews. If you're preparing for frontend roles, this will be a strong revision resource. #React #JavaScript #Frontend #WebDevelopment #ReactJS #SoftwareEngineering #InterviewPreparation #CodingInterview #FrontendDeveloper #UIEngineering #JSX #Rendering #VirtualDOM #Reconciliation #Programming #Developers #TechCareers #CareerGrowth #LearningInPublic #InterviewGuide

🚀 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

🚀 React JS Interview Questions You Should Prepare in 2026 If you're preparing for a frontend role, especially in React, these are the questions you’ll most likely face 👇 🧠 Core React Concepts ✔ What is Virtual DOM and how does it work? ✔ Difference between state and props? ✔ What are hooks and why are they used? ✔ Explain component lifecycle ⚛️ Hooks (Very Important) ✔ What is useState and useEffect? ✔ When does useEffect run? ✔ What are custom hooks? ✔ Difference between useMemo and useCallback 🔄 State Management ✔ When to use Context API vs Redux? ✔ How does Redux work internally? 🌐 API & Async Handling ✔ How do you fetch data in React? ✔ How do you handle loading & error states? ⚡ Performance Optimization ✔ What is lazy loading? ✔ What is memoization in React? ✔ How to avoid unnecessary re-renders? 🧪 Testing ✔ How do you test React components? ✔ Have you used Jest? 🚀 Advanced (Stand Out Questions) ✔ What are Server Components in Next.js? ✔ Difference between CSR, SSR, and SSG? ✔ How does reconciliation work? 💡 Real Interview Tip: Don’t just answer theory. 👉 Always explain with a real project example 🔥 Pro Tip: If you can confidently answer these, you're already ahead of 70% of candidates. 💬 What’s the toughest React question you’ve faced in an interview? #ReactJs #FrontendDevelopment #WebDevelopment #JavaScript #TechInterviews #SoftwareEngineering #Developers #CareerGrowth #NextJS #CodingInterview

🚀 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

🚀 MASTER YOUR REACT INTERVIEW! 💻 Are you ready to level up your frontend game? ReactJS continues to dominate the web development landscape, and being "interview-ready" is about more than just writing code—it's about understanding the core architecture. I’ve compiled a comprehensive guide to the most essential ReactJS Interview Questions to help you ace your next technical round! 🎯 What’s inside this guide? 🔹 Core Fundamentals: The "What" and "Why" of React's declarative approach. 🔹 The Virtual DOM: Understanding Reconciliation and how React optimizes performance. 🔹 Features & Architecture: JSX, Server-Side Rendering (SSR), and Unidirectional Data Flow. 🔹 React vs. ReactDOM: Knowing the difference and why it matters for cross-platform development. 🔹 Component Mastery: State vs. Props, and the power of reusable UI components. Whether you're a Junior Developer starting your journey or a Senior Engineer brushing up on the basics, these concepts are the foundation of building scalable modern applications. 💡 Pro-tip: Don't just memorize the answers. Focus on the "Why." Understanding how React handles the DOM under the hood will make you a much stronger developer! 👉 SWIPE THROUGH to see the full breakdown! What’s one React concept that always trips you up in interviews? Let's discuss in the comments! 👇 #ReactJS #WebDevelopment #CodingInterview #JavaScript #FrontendDeveloper #SoftwareEngineering #TechCareer #WebDevTips #ReactHooks #CodingLife #Programming #FullStackDeveloper #KhushiKumari #TechInterviewPrep #VirtualDOM #JSX #WebDevCommunity

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

🚀 Built something for every frontend developer preparing for interviews! I’ve created a complete Preparation Guide that covers everything you actually need 👇 💡 What you’ll find inside: • 🌐 HTML, CSS & JavaScript fundamentals • ⚛️ Core concepts of React • 🧠 Machine Coding Round Questions • 📚 Structured topics & subtopics for focused learning No more random resources — everything is organized in one place to help you prepare smarter, not harder 🎯 🔗 Check it out: https://lnkd.in/geXQnzhA Would love your feedback 🙌 Let’s help each other grow 🚀 #FrontendDeveloper #React #JavaScript #WebDevelopment #CodingInterview #MachineCoding #HTML #CSS