React Virtual DOM: 5-Step Explanation

🤯 I learned something today that completely changed how I see React. I've been using React for a while. But today I finally understood what's happening UNDER THE HOOD. Let me break it down 👇 🌳 The Problem with the Real DOM When your browser loads a page, it builds a tree of every element — buttons, divs, headings. That's the DOM. Every time something changes, the browser rebuilds parts of that tree. And touching the real DOM is SLOW. Imagine repainting one brick but rebuilding the entire wall to do it. 😩 ⚛️ So React created the Virtual DOM React keeps a lightweight copy of the DOM in JavaScript memory — invisible to the browser. Think of it as a blueprint of your house. Not the house itself. 🔄 What happens when state changes: 1️⃣ React takes a snapshot of the current Virtual DOM 2️⃣ Creates a new Virtual DOM with the update applied 3️⃣ Diffs the two — finds exactly what changed 4️⃣ Updates ONLY those parts in the real DOM Not the whole page. Just the diff. 🎯 The analogy that made it click: Bad way → Rewrite the entire Google Doc every time you fix a typo. React's way → Just fix the typo. Nothing else changes. That's the Virtual DOM. Every single update. 📌 DR: → React creates a Virtual DOM in memory → On state change, diffs old vs new → Updates ONLY what changed in the real DOM → Result = fast, smooth, efficient UI Most people use React for months before understanding this. Once you get it — everything makes sense. What's one concept that clicked for you late? Drop it below 👇 #React #ReactJS #JavaScript #WebDevelopment #Frontend #100DaysOfCode #LearnInPublic Sheryians Coding School Daneshwar Verma Devendra Dhote Ritik Rajput

🚀 Understanding Class Components in React One concept that helped me understand how components work internally was Class Components. Before Hooks became popular, class components were the primary way to manage state and lifecycle methods in React applications. A class component is simply a JavaScript class that extends React.Component and must contain a render() method that returns JSX. Example: import React, { Component } from "react"; class Welcome extends Component { render() { return <h1>Hello World</h1>; } } export default Welcome; In class components: 🔹 Props are accessed using this.props 🔹 State is managed using this.state 🔹 State updates are done with this.setState() 🔹 Lifecycle methods like componentDidMount() allow us to run code when the component mounts, updates, or unmounts. Example with state: class Counter extends Component { state = { count: 0 }; increase = () => { this.setState({ count: this.state.count + 1 }); }; render() { return ( <button onClick={this.increase}> {this.state.count} </button> ); } } Today, most developers prefer Functional Components with Hooks like useState and useEffect, but understanding Class Components is still valuable because: ✅ Many legacy React projects still use them ✅ They help you understand React's lifecycle deeply ✅ Some interview questions still cover them Learning both approaches gives you a stronger foundation in React. Sometimes, understanding the old way helps you appreciate the modern way even more. #React #FrontendDevelopment #JavaScript #WebDevelopment #LearningInPublic

Why building a "simple" Accordion is actually a Masterclass in React State 🚀 I recently spent some time building a custom Accordion component from scratch. On the surface, it’s just showing and hiding text. But under the hood, it was a great challenge in managing complex UI logic. The Challenges I Faced: Single vs. Multi-Selection: Moving from a single state (one item open) to an array-based state (multiple items open) required a total shift in how I thought about data flow. The "Double Arrow" Trap: I ran into a classic bug where my onClick was returning a function instead of executing it. A great reminder that how we call handlers in JSX matters! State Latency: Learning that console.log right after setState shows the old value, not the new one, was a lightbulb moment for me regarding React’s asynchronous nature. Why not just use the HTML <details> tag? While <details> is great for simple use cases, I chose React state because: Exclusive Selection: <details> doesn't natively support "close others when one opens." State Control: I needed the app to "know" which items were open to perform other logic. Animations: React state allows for much smoother transitions and custom styling that matches the brand perfectly. Check out the snippet below! It’s not about finding the easiest way; it’s about finding the way that gives you the most control. #ReactJS #WebDevelopment #CodingJourney #Frontend #Javascript #LearningInPublic

Bubbling Concept in React: A Practical Breakdown 🚀 Why Your React Button Click Triggers the Parent (And How to Fix It) One small function can save you from unexpected UI behavior: e.stopPropagation() But what does it actually do? In JavaScript and React, events “bubble up” the DOM tree. That means when you click on a child element, the click event also triggers on its parent elements. Example: <div onClick={() => console.log("Parent clicked")}> <button onClick={() => console.log("Button clicked")}> Click Me </button> </div> If you click the button, the console will log: Button clicked Parent clicked Why? Because the click event bubbles from the button to the parent. 🛑 Preventing Event Bubbling If you want the button click to NOT trigger the parent’s click handler, use: <button onClick={(e) => { e.stopPropagation(); console.log("Button clicked"); }} > Click Me </button> Now only this runs: Button clicked 🛒 Real-World Example Imagine a clickable product card: <div onClick={() => navigate("/product/1")}> <button onClick={addToCart}> Add to Cart </button> </div> Without stopPropagation(), clicking “Add to Cart” will also navigate to the product page. Solution: <button onClick={(e) => { e.stopPropagation(); addToCart(); }} > Add to Cart </button> Now: ✅ The product is added to cart ✅ No unwanted navigation Understanding event propagation is essential for building predictable and clean UI behavior in React applications. Small detail. Big impact. #React #JavaScript #FrontendDevelopment #WebDevelopment

📌 Today I learned: useReducer — React's powerful alternative to useState When state logic gets complex, useReducer brings structure and clarity. The core concept: ``` const [state, dispatch] = useReducer(reducer, initialState); ``` Instead of directly updating state, you dispatch **actions**. The reducer — a pure function — takes the current state + action and returns the next state. 🔑 Key benefits I discovered: → Centralised logic — all state transitions live in one function → Easier debugging — every state change has an explicit action → Scales better — perfect for complex UI with multiple transitions → More testable — reducers are just pure functions! UseReducer shines when: • You have 3+ related state variables • State updates depend on previous state • Multiple actions affect the same piece of state Think of it like Redux — but built right into React, no extra libraries needed. One day of learning, but the concept already feels foundational. Excited to keep building with it! 🚀 #ReactJS #useReducer #StateManagement #JavaScript #WebDevelopment #FrontendDev #LearningInPublic

🚀 React Hooks Small Projects I recently worked on a few small projects to better understand some important React Hooks. In this video, I demonstrated how these hooks work with simple examples so that beginners can easily understand their usage. 🔹 useState – Used to manage state inside a functional component. It helps update and display dynamic data in the UI. 🔹 useEffect – Used to handle side effects in React applications such as API calls, timers, and updating the DOM when state changes. 🔹 useContext – Helps share data globally across components without passing props manually through every level. 🔹 useReducer – A powerful hook for managing complex state logic, especially when multiple state updates depend on different actions. 🔹 useMemo – Optimizes performance by memoizing expensive calculations so they only run when dependencies change. 🔹 useCallback – Returns a memoized function to prevent unnecessary re-renders when passing functions to child components. These mini projects helped me strengthen my understanding of React Hooks and component optimization techniques. 📌 If you watch the video, you can easily understand how each hook works in a practical way. #ReactJS #ReactHooks #WebDevelopment #MERNStack #JavaScript #FrontendDevelopment #CodingPractice

A very common React mistake I see developers make: Mutating State When I was learning React, one concept that changed the way I write code was this rule: 👉 React state must never be mutated.its always immutable. But why? React does not deeply compare objects or arrays when state updates. Instead, it performs a reference(memory) comparison. That means React checks: Old State === New State ? If the reference is the same, React assumes nothing changed and skips re-rendering. Example of a mistake: cart.push(product) // ❌ Mutating state setCart(cart) Here we modified the same array in memory, so React may not detect the change because the memory location is same.so no re-render..no UI update. The correct approach is immutability: setCart([...cart, product]) // ✅ Creating a new array Now React sees a new reference, triggers reconciliation, and updates the UI correctly. 💡 Why React prefers immutability: • Faster change detection • Predictable state updates • Easier debugging • Better performance This small concept explains why patterns like: map() filter() spread operator (...) are used so frequently in React. because all this returns new object or array... Understanding this helped me write cleaner and more reliable React components. What React concept took you the longest to understand? 🤔 #React #Frontend #JavaScript #WebDevelopment #ReactJS

Most students jump into React too early. Yes, I said it. They install: • React • Next.js • 10 npm packages But can’t explain how the DOM works Frontend is not about frameworks. It’s about understanding the foundation: • HTML → Structure • CSS → Layout & Design • JavaScript → Logic & Interaction If you don’t understand: • How the browser renders a page • What the event loop does • How CSS positioning really works • How state changes update the UI Then React will feel like magic. And magic breaks when something goes wrong. When I started focusing on: • Flexbox and Grid deeply • Vanilla JavaScript projects • Building small components from scratch Everything changed. Frameworks stopped being confusing. They became just tools means to an end, not the end itself. If you’re a student learning frontend right now: 1️⃣ Master JavaScript before React 2️⃣ Build 3–5 small projects without frameworks 3️⃣ Learn how APIs actually work 4️⃣ Debug without immediately searching StackOverflow Frontend isn’t about memorizing syntax. It’s about understanding how the browser thinks. And once you get that… You become dangerous (professionally speaking 😉). What frontend concept took you the longest to understand? #FrontendDevelopment #WebDevelopment #SoftwareEngineering #CodingJourney #CSStudents

Why React Re-Renders (And Why That’s Not Always Bad) One of the most common things I hear about React: “It’s re-rendering again.” And it’s usually said like… something is broken. But here’s the truth: Re-renders are not the enemy. They’re how React works. 🔁 What Actually Triggers a Re-Render? A component re-renders when: - Its state changes - Its props change - Its parent re-renders That’s it. React doesn’t randomly re-render your components. It responds to change. 😅 The Misconception Many developers try to prevent every re-render using: - useMemo - useCallback - React.memo But here’s the question: Are the re-renders actually expensive? Because most of the time… They’re not. React’s reconciliation is fast. Rendering a few components again usually costs almost nothing. ⚠️ When Re-Renders Become a Problem Re-renders matter when: - You’re rendering large lists - Heavy computations run on every render - Expensive child components re-render unnecessarily That’s when optimization makes sense. Not before. 🧠 The Mental Shift Instead of asking: “How do I stop this from re-rendering?” Ask: “Is this re-render actually causing a performance issue?” Measure first. Optimize second. 💡 Final Thought React is built around predictable re-renders. Trying to eliminate them entirely often: - Adds complexity - Makes code harder to read - Introduces subtle bugs Clean code + correct mental model > aggressive optimization. Follow for more practical breakdowns. #ReactJS #JavaScript #FrontendDevelopment #SoftwareEngineering #WebDevelopment #ReactHooks

POV: You start React thinking it’s just “thoda sa JSX” 🤡 Then suddenly you are stuck between Virtual DOM, Babel, Fiber Nodes, Reflow, Re-rendering and your brain says: “bhai ye sab kya chal raha hai?” 😭 Today’s React Revision & Deep Dive was like a full frontend rollercoaster 🎢 Revised topics: ⚛️ Real DOM vs Virtual DOM 🧠 JSX 🔄 Babel ⚡ Vite Bundler 📦 Props 🪜 Props Drilling 🔘 useState Hook 🧩 Components 🧵 React Fiber Nodes 🎨 Reflow & Repaint 🔁 Reload / Re-render Behavior The more I revise React, the more I realize that React is not just about making UI… It’s about understanding what happens behind the scenes when the UI changes. Big thanks to my Guruji Devendar Dhote for guiding and helping me see React beyond just syntax 🙏 Still learning, still revising, still trying to decode how React actually thinks 🚀 #React #JavaScript #WebDevelopment #Frontend #LearningInPublic #ReactJS A slightly more savage Gen Z version: Started React with: “haan haan sab samajh aa gaya” 😎 Then React said: “Accha? Bata Fiber kya hota hai.” 💀 So today I revised: Real DOM, Virtual DOM, JSX, Babel, Vite, Props, Props Drilling, useState, Components, React Fiber Nodes, Reflow & Repaint, and Re-render behavior. At this point, React is teaching me that frontend is not just design and buttons — it’s pure behind-the-scenes madness + smart UI updates. Huge respect to my Guruji Devendra Dhote for the guidance 🙏 Day by day, trying to understand React deeper than just tutorials. #React #JavaScript #WebDev #FrontendDevelopment #LearningInPublic