React Concepts for Efficient UI: Event Delegation & Synthetic Events

🚀 Day 1 to 5 of Learning React — Understanding JSX & Babel (Behind the Scenes) Today I explored how React actually works under the hood, and honestly… it’s pretty cool • What is JSX? JSX stands for JavaScript XML. It allows us to write HTML-like code inside JavaScript. Example: const element = <h1>Hello World</h1>; But here’s the catch Browsers don’t understand JSX directly • Role of Babel Babel is a transpiler that converts JSX into normal JavaScript. Above JSX becomes: React.createElement("h1", null, "Hello World"); So basically: • JSX → Babel → JavaScript → Browser • How React works behind the scenes React creates a Virtual DOM Instead of updating the real DOM directly (which is slow), React: 1. Creates a Virtual DOM (lightweight copy) 2. Compares changes (Diffing) 3. Updates only the changed parts (Reconciliation) • This makes React super fast Key Takeaway: React is not magic — it’s just smart optimization + JavaScript power. # Next: Diving deeper into Components & Hooks #ReactJS #WebDevelopment #JavaScript #LearningInPublic #Frontend #CodingJourney Vikas Kumar Prashant Pal Pratyush Mishra Prakash Sakari Likitha S Rajit Ram GeeksforGeeks

React fundamentals to get right early Understanding onClick and onChange is key to handling events correctly in React A common pattern to be aware of: onClick={handleClick(id)} This executes immediately during render --- Correct approach: onClick={() => handleClick(id)} This runs only when the user clicks --- Why? React expects a function reference, not a function call - handleClick → correct - handleClick() → executes immediately --- Same concept applies to onChange: onChange={handleChange(value)} // executes immediately Better: onChange={(e) => handleChange(e.target.value)} --- Simple rule: If you need to pass arguments → use an arrow function --- Things to watch out for: - Functions running on every render - Unintended API calls - Difficult-to-debug behavior --- Benefits of correct usage: - Runs only on user interaction - More predictable component behavior - Cleaner and maintainable code --- Additional note: onClick={handleClick} (if your function expects arguments) This may result in "undefined" --- Example: {users.map(user => ( <button onClick={() => handleClick(user.id)}> Click </button> ))} --- Focusing on fundamentals like this helps build more reliable React applications #ReactJS #JavaScript #Frontend #WebDevelopment

🚀 Day 27 — React Conditional Rendering using if-else Today I learned how Conditional Rendering works in React using the if-else approach 👇 In React, conditional rendering works just like JavaScript conditions. We can use: 🔹 if-else 🔹 switch-case 🔹 ternary operator 🔹 logical operators (&&) to display UI based on specific conditions. 🧩 Example: Using if-else const Conditional1 = () => { const [displayText, setDisplayText] = useState(true); if (displayText) { return ( <> <h1>Welcome to Testyantra Software Solutions</h1> <p>Lorem ipsum dolor sit amet...</p> </> ); } else { return <h1>No data found</h1>; } }; ✅ Key Learnings 🔹 UI changes dynamically based on state 🔹 if-else is best for clear multi-line JSX conditions 🔹 Makes components flexible and interactive 💡 Conditional rendering is one of the core concepts for building real-world React applications. 🔥 Every small concept is helping me become stronger in frontend development. #React #ConditionalRendering #FrontendDevelopment #JavaScript #WebDevelopment #10000 Coders

🚀 Day 34 — #CSS in #React_JS (#Module_CSS) Today I learned how Module CSS works in React JS 🎨 When we want to apply CSS only to a specific component or a set of components, Module CSS is the best approach. 🧩 How it Works 🔹 Create a file with .module.css extension 🔹 Import that CSS file inside the required component 🔹 Use the imported variable name with className or id 🧩 Example import styles from "./Button.module.css"; function Button() { return <button className={styles.btn}>Click Me</button>; } ✅ Key Learnings 🔹 Styles are scoped only to that component 🔹 Prevents class name conflicts 🔹 Great for reusable UI components 🔹 Best for large-scale React applications 💡 Module CSS makes component styling clean, safe, and maintainable. 🔥 Learning styling architecture is making my React projects more professional. #React #CSS #ModuleCSS #FrontendDevelopment #JavaScript #WebDevelopment #10000 Coders

Have you ever paused to think about how JavaScript’s asynchronous nature has completely transformed our lives as developers? From eliminating blocking code to enabling smooth, non-blocking user experiences — async programming is the reason modern web apps feel so fast and responsive today. In my latest blog, I break down the fundamentals of Synchronous and Asynchronous JavaScript. 🔗 Read the full post here: https://lnkd.in/egq38-vw Would love to hear from you in the comments 👇 Grateful to the incredible Chai Aur Code community that keeps pushing us forward every day! Hitesh Choudhary Piyush Garg Akash Kadlag Anirudh J. Suraj Kumar Jha Jay Kadlag Nikhil Rathore #JavaScript #WebDevelopment #AsyncJS #Coding #DeveloperLife #TechBlog #Chaicode #Cohort

🚀 Feature Update: Registration Form Validation (React Project) Excited to share the latest functionality I implemented in my React project 👨💻 🔹 Key Features Added: 🔹 Display error message "Required" when input fields are empty on blur 🔹 On Submit: 🔹 Shows error if only First Name is entered 🔹 Shows error if only Last Name is entered 🔹 Shows error if both fields are empty 🔹 Displays Registration Success View on successful submission 🎉 🔹 Added "Submit Another Response" button to reset and reuse the form 💡 This helped me understand: 🔹 Form validation techniques 🔹 Handling user input efficiently 🔹 Improving user experience with real-time feedback 🔧 Tech Used: React.js, JavaScript, CSS 🔗 GitHub Repo: https://lnkd.in/gy5jzHiG #ReactJS #FrontendDevelopment #WebDevelopment #JavaScript #LearningJourney #Projects

The map() function is one of the most commonly used methods in JavaScript — especially in React applications. It allows you to transform array data and return a new array. In this video, I explain: • How map() works internally • How it processes each element • How to modify values • Why it always returns a new array • Difference between map() and filter() Example: [1,2,3] → [2,4,6] map() is widely used for: • Rendering lists in React • Transforming API data • UI logic Understanding map is essential for writing efficient frontend code. 🎓 Learn JavaScript & React with real-world projects: 👉 https://lnkd.in/gpc2mqcf 💬 Comment Link and I’ll share the complete JavaScript roadmap. #JavaScript #ReactJS #FrontendEngineering #WebDevelopment #SoftwareEngineering #Programming #DeveloperEducation

🚀 Immediately Invoked Function Expressions (IIFEs) (JavaScript) An Immediately Invoked Function Expression (IIFE) is a JavaScript function that executes as soon as it is defined. IIFEs are commonly used to create a private scope, preventing variables declared within the IIFE from polluting the global scope. This helps avoid naming conflicts and improves code encapsulation. IIFEs are a useful pattern for modularizing code and creating self-contained units of functionality. Learn more on our app: https://lnkd.in/gefySfsc #JavaScript #WebDev #Frontend #JS #professional #career #development

🚀 What is a Polyfill in JavaScript? (And why every frontend dev should care) Ever tried using a modern JS feature… and it just breaks in older browsers? 😅 That’s where Polyfills come in. 👉 A polyfill is a piece of code that adds support for features that a browser doesn’t natively support. 💡 Simple idea: “If the browser doesn’t support it, I’ll implement it.” 🔧 Example: Array.includes() polyfill if (!Array.prototype.includes) { Array.prototype.includes = function (value) { return this.indexOf(value) !== -1; }; } ✔️ Now even older browsers can use includes()! ⚙️ Why Polyfills Matter Ensure cross-browser compatibility Let you use modern JavaScript safely Critical for production-grade apps 🧠 Polyfill vs Transpiler Polyfill → Adds missing functionality Transpiler (Babel) → Converts modern syntax to older syntax 👉 You often need both in real-world apps. 📦 Pro Tip Instead of writing polyfills manually: Use core-js Use CDN like polyfill.io Let Babel handle it automatically ⚠️ Be mindful Polyfills can increase bundle size — use them only when necessary. 🔥 Takeaway Polyfills help you write modern code without breaking older environments — making your app more reliable and user-friendly. #JavaScript #WebDevelopment #Frontend #Coding #SoftwareEngineering #DevTips #100DaysOfCode #Programming #Tech #Developers

Why do we need to call 'super(props)' in the constructor of a React component? JavaScript classes aren't magic. They are just syntactic sugar over prototypes. If you are still using (or have used) Class Components in React, you have likely typed 'super(props)' a thousand times. But do you actually know what happens if you forget it? In JavaScript, you cannot use the keyword 'this' in a constructor until you have called the parent constructor. Since your component extends 'React.Component', calling 'super()' is what actually initializes the 'this' object. If you try to access 'this.state' or 'this.props' before that call, JavaScript will throw a ReferenceError and crash your app. But why pass 'props' into it? React sets 'this.props' for you automatically after the constructor runs. However, if you want to access 'this.props' inside the constructor itself, you must pass them to 'super(props)'. If you just call 'super()', 'this.props' will be undefined until the constructor finishes execution. Most of us have moved to Functional Components where this isn't an issue. But understanding these fundamentals is what separates a developer who just writes code from one who understands the runtime. #ReactJS #Javascript #SoftwareEngineering #WebDevelopment #Coding #ProgrammingTips