Code Splitting in React: Smaller Bundles for Faster Load Times

Day 3 of my Interview Preparation 🚀 Today I revised some important JavaScript concepts: • What is React? • What is JSX? • Props in React • useState Hook (State management) • Event Handling in React • React Functional Components Consistent learning every day to improve my skills in **JavaScript, React.js, and Web Development**. #javascript #reactjs #webdevelopment #frontenddeveloper #learninginpublic #100daysofcode

A few weeks ago, I talked about closures in JavaScript because it’s a concept that is frequently asked in technical interviews. But closures are not just an interview topic. They are used all the time in real applications — including React. A good example is React’s useState hook. In the simplified example in the image, both functions returned from the outer function still have access to the same `state` variable. Even though the outer function has already finished executing, those inner functions "remember" the environment where they were created. That’s exactly what a closure is. This is the core idea React relies on to preserve state between renders: functions that still have access to values created earlier. Of course, React’s real implementation is more complex, but the underlying concept is the same. Understanding these fundamentals makes React hooks feel much less like magic, and shows how many of the frameworks and libraries we use every day are built on top of simple JavaScript concepts. #React #JavaScript #Frontend #WebDevelopment #SoftwareEngineering

15 JavaScript interview questions. Promises & Async/Await. Answer karo comments mein 👇 Promises Q1. What is a Promise in JavaScript and why does it exist? Q2. What is the difference between resolve and reject? Q3. What does .then() return? Q4. What is the difference between .catch() and the second argument of .then()? Q5. What does .finally() do? Async/Await Q6. What is async/await and how does it relate to Promises? Q7. What does an async function always return? Q8. Can you use await outside an async function? Q9. What happens if you don't use try/catch with async/await? Q10. What is the difference between sequential and parallel async calls? Promise Methods Q11. What is the difference between Promise.all and Promise.allSettled? Q12. What is Promise.race and when would you use it? React Connection Q13. Why can't useEffect callback be directly async? Q14. What is the standard loading/error/data pattern in React? Q15. What is the difference between async errors and sync errors in React? Full answers + code on GitHub 👇 https://lnkd.in/dj72-XEi #JavaScript #JStoReact #InterviewPrep #WebDevelopment #Frontend #ReactJS #30DayChallenge #JavaScriptTips #FrontendDeveloper #100DaysOfCode

💡 Most Asked Frontend Interview Question: 👉 “Can you explain the Event Loop in JavaScript?” Here’s the simplest way to think about it 👇 JavaScript is single-threaded. It can only do one thing at a time. So how does it handle async tasks like API calls, timers, or promises without blocking the main thread? 👉 That’s where the Event Loop comes in. 🌀 How it works (in simple words): 1️⃣ JavaScript executes code line by line in the Call Stack 2️⃣ Async tasks (setTimeout, promises, APIs) are handled by Web APIs / background 3️⃣ Once completed, callbacks move to: → Callback Queue / Microtask Queue 4️⃣ The Event Loop constantly checks: 👉 Is the Call Stack empty? ✔ If yes → it pushes tasks from the queue into the stack 💡 That’s how JavaScript appears asynchronous even though it runs on a single thread. 👉 If you don’t understand the Event Loop, you don’t truly understand JavaScript. Follow Hrithik Garg 🚀 for more frontend interview content. #javascript #frontend #webdevelopment #interviewprep #coding #reactjs #angular

🚀 React Interview Series | Day 3: Why is State “Async”? You click a button, call: 👉 setCount(count + 1) 👉 then immediately: console.log(count) And boom… you still see the old value 😵 💡 The Real Talk: I’ve seen candidates panic in live coding rounds when this happens. They assume something is broken. It’s not. React is just being smart. Instead of updating state instantly, React batches updates to improve performance. 👉 Multiple state updates = ❌ multiple re-renders 👉 Batched updates = ✅ single efficient re-render 🧠 What’s Actually Happening? React waits until your function finishes execution, then processes all state updates together. That’s why you don’t see the updated value immediately. 🔥 The “Senior” Way to Handle It: If your next state depends on the previous one, never rely on the current variable. Use the functional update pattern 👇 setCount(prevCount => prevCount + 1); ✅ Always gets the latest value ✅ Works correctly even with multiple queued updates 🎯 Key Takeaway: If you understand this, you're already thinking like a senior developer. 💬 Have you ever been confused by this behavior in React? Drop your experience below 👇 #ReactJS #JavaScript #FrontendDevelopment #WebDevelopment #CodingInterview #ReactTips

The scariest interview question isn’t a complicated one. It’s usually the simplest. “Can you explain closures?” Because that question quickly shows whether someone memorized JavaScript… or actually understands how it works. Closures aren’t magic. They don’t store copies of variables. They access variables from their lexical scope. That small detail explains a lot: • Why state can persist between function calls • Why async callbacks behave the way they do • Why some bugs feel unpredictable Closures aren’t an advanced trick. They’re part of the foundation of JavaScript. And in my experience, strong developers aren’t defined by frameworks or tools. They’re defined by how well they understand the fundamentals. A simple test: If someone asked you to explain closures without using the word “remember” Could you do it? #FullStackDeveloper #WebDevelopment #DeveloperRoadmam #ReactJS #JavaScript #BuildInPublic #LearningInPublic #CareerGrowth

🛑 STOP using useCallback for everything! In a React interview, if you say "I wrap every function in useCallback to make it faster," you might have just talked yourself out of the job. Why? Because memoization isn't free. Every hook has a cost in memory and initialization. Here is the Right vs. Wrong way to use it: ❌ THE WRONG WAY: "Optimization Overkill" JavaScript const handleClick = useCallback(() => { console.log("Button clicked!"); }, []); return <button onClick={handleClick}>Click Me</button>; The Verdict: This is actually slower. You’ve created a function, created a hook, and performed a dependency check—all to "optimize" a standard HTML button that React would have rendered in milliseconds anyway. ✅ THE RIGHT WAY: "Preventing the Ripple Effect" const handleUpdate = useCallback((id) => { updateUser(id); }, [updateUser]); // Chart is wrapped in React.memo() return <ExpensiveChart onUpdate={handleUpdate} />; The Verdict: This is a win. ExpensiveChart is a heavy component wrapped in React.memo. If you don't use useCallback, the handleUpdate reference changes on every render, breaking the memoization and forcing the heavy chart to re-render unnecessarily. 💡 The Golden Rule: Only use useCallback when: -The function is passed as a prop to a memoized child component (React.memo). -The function is a dependency in another hook (like useEffect). Junior Devs: Optimize for readability first. Senior Devs: Optimize when the Profiler proves there’s a bottleneck. Which side are you on? Let’s discuss in the comments! 👇 #ReactJS #WebDevelopment #Frontend #SoftwareEngineering #CodingTips #Programming

Day 51/100 Day 28 of 30 – React Series 💡 Today’s Topic: Top React Interview Questions If you're preparing for React interviews, these are the most frequently asked questions in React. Save this post 📌 🧠 Core React Questions 👉 What is React? 👉 What is Virtual DOM? 👉 Difference between Real DOM vs Virtual DOM? 👉 What are components? ⚛️ JSX & Components 👉 What is JSX? 👉 Difference between Functional vs Class Components? 👉 What are props? 👉 What is prop drilling? 🔁 Hooks (Very Important 🔥) 👉 What is useState? 👉 What is useEffect? 👉 What is useRef? 👉 Difference between useMemo vs useCallback? 👉 What are custom hooks? 🔄 State Management 👉 What is lifting state up? 👉 Context API vs Redux? 👉 What is global state? ⚡ Performance Optimization 👉 What is React.memo? 👉 When to use useMemo? 👉 When to use useCallback? 👉 How to prevent unnecessary re-renders? 🌐 Routing & Advanced Concepts 👉 What is React Router? 👉 What are keys in React? 👉 What is lazy loading? 👉 What are Error Boundaries? 🎯 Coding Questions 👉 Reverse a string using React state 👉 Build a counter app 👉 Create a form with validation 👉 Fetch API data and display list 💡 Pro Tips for Interviews ✅ Explain concepts with examples ✅ Focus on hooks (very important) ✅ Practice real-world scenarios ✅ Be clear about performance optimization 🧠 Bonus: 1-Line Answers Virtual DOM → Fast UI updates useEffect → Side effects useRef → No re-render storage React.memo → Prevent re-renders Master these questions → You’re ready for React interviews 🚀 #React #JavaScript #FrontendDeveloper #WebDevelopment #100DaysOfCode #FullStackDeveloper

🚀 5 Advanced JavaScript Interview Questions Every Developer Should Know JavaScript interviews often go beyond basics. Understanding core concepts helps you write cleaner and more efficient code. Here are 5 advanced JavaScript questions with simple explanations: 1️⃣ What is Closures in JavaScript? A closure occurs when a function remembers variables from its outer scope even after the outer function has finished executing. 2️⃣ What is the Event Loop? The event loop allows JavaScript to handle asynchronous operations like API calls and timers by managing the call stack and callback queue. 3️⃣ What is the difference between == and ===? • == → Compares values after type conversion • === → Strict comparison (value + type) 4️⃣ What is Hoisting in JavaScript? Hoisting means variable and function declarations are moved to the top of their scope during compilation. 5️⃣ What are Promises in JavaScript? Promises handle asynchronous operations and have three states: Pending → Fulfilled → Rejected. 💡 Understanding these concepts helps developers build scalable and reliable applications. #JavaScript #WebDevelopment #Frontend #MERN #Programming #CodingInterview #Developer #JS

🎯 Important JavaScript Topics for Backend / Node.js Interview... While preparing for backend interviews, I noticed that many companies focus on core JavaScript fundamentals before moving to Node.js concepts. Here are some important JavaScript topics every backend developer should be comfortable with: 🔹 Closures – One of the most commonly asked concepts 🔹 Promises & async/await – Handling asynchronous operations 🔹 Event Loop & Call Stack – How JavaScript handles concurrency 🔹 this keyword – Behavior in different contexts 🔹 Arrow functions vs normal functions 🔹 Prototypes & inheritance 🔹 Hoisting (var, let, const differences) 🔹 Array methods (map, filter, reduce) 👉 One thing I’ve realized: Strong JavaScript fundamentals make it much easier to understand Node.js internals and backend behavior. Before mastering frameworks, mastering the language itself makes a huge difference. 💬 Which JavaScript concept took you the longest to fully understand? #JavaScript #NodeJS #BackendDeveloper #InterviewPreparation #WebDevelopment #TechLearning