React Re-renders: What You Need to Know

⚛️ React Tip: When Should You Use useCallback? While working on React applications, one common performance issue developers face is unnecessary component re-renders. One hook that often comes up in this discussion is useCallback. But many developers (including me earlier) either overuse it or use it incorrectly. So here’s a simple way to understand it. 🔹 What does useCallback do? `useCallback` memoizes a function. This means React will reuse the same function instance unless its dependencies change. Example 👇 const handleClick = useCallback(() => { console.log("Button clicked"); }, []); Without `useCallback`, a new function is created every time the component re-renders. Most of the time this isn’t a problem. But it becomes important when passing functions to memoized child components. 🔹 Example scenario Imagine a parent component passing a function as a prop to a child component wrapped with `React.memo`. If the function reference changes on every render, the child component will also re-render unnecessarily. Using `useCallback` helps keep the function reference stable, preventing those extra renders. 🔹 When should you actually use it? ✅ When passing callbacks to memoized components ✅ When the function is a dependency in another hook ✅ When optimizing large component trees ⚠️ When NOT to use it: • For every function in your component • When there is no performance issue • Just because someone said it improves performance 💡 One important lesson I’ve learned: Optimization should be intentional, not automatic. React already does a lot of work under the hood. Use hooks like `useCallback` only when they actually solve a problem. Curious to hear from other developers 👇 Do you use `useCallback` often, or do you prefer optimizing only after profiling? #reactjs #frontenddevelopment #javascript #webdevelopment #reacthooks #softwareengineering #coding

Lazy Loading in React, Boost Performance Like a Pro! Lazy loading is a powerful technique in React where components are loaded only when they are needed, instead of loading everything at once. 👉 Think of it as: Lazy Loading = Code Splitting = Dynamic Imports = On-demand Loading 💡 Why use Lazy Loading? ✔️ Improves performance ✔️ Reduces initial bundle size ✔️ Faster page load experience 🛠️ Key Methods - React.lazy() - for dynamic imports - Suspense - for fallback UI (like loaders) 📌 Basic Syntax const Component = React.lazy(() => import('./Component')); <Suspense fallback={<h1>Loading...</h1>}> <Component /> </Suspense> ⚙️ How it works - Components load only when required - A fallback UI is shown until loading completes 📍 Common Use Cases - Routing (React Router) - Large components - Dashboards ⚠️ Important Points - Works with default exports only - Must be wrapped inside Suspense - It’s a key part of code splitting 🔥 If you are aiming for scalable and high-performance React apps, lazy loading is a must-know concept! #ReactJS #JavaScript #WebDevelopment #FrontendDevelopment #CodeSplitting #PerformanceOptimization #ReactDeveloper #Programming #TechTips #SoftwareDevelopment

Using index as a key is dangerous Every React developer has written this at least once. items.map((item, index) => (  <li key={index}>{item}</li> )) Looks fine. Works fine. But it isn't This is Post 5 of the series: 𝗥𝗲𝗮𝗰𝘁 𝗨𝗻𝗱𝗲𝗿 𝘁𝗵𝗲 𝗛𝗼𝗼𝗱 Where I explain what React is actually doing behind the scenes. Here's what actually happens when you use index as key: You delete one item from a list. React doesn't know which item was removed. It just looks at positions. So it re-renders everything from that index downward. Input states get mismatched. Animations break. Bugs appear that you can't even reproduce consistently. And... No error. Just... wrong behavior. 🔑 Here's what React actually needs: A key isn't just something unique. It needs to be stable, unique, AND tied to the data — not the position. ❌ key={index} → breaks on delete, sort, filter  ❌ key={Math.random()} → new key every render = React destroys and recreates the node  ✅ key={item.id} → stable, reliable, React knows exactly who is who The rule is simple: If your list can ever be reordered, filtered, or deleted from... index as key will silently break your UI. Use your data's ID.  If it doesn't have one, generate it at creation — not during render. const newItem = { id: crypto.randomUUID(),   name: "New Task" } One tiny prop.  Massive impact on how React tracks your entire list. In Post 6 of React Under the Hood: What Happens When You Call setState Follow Farhaan Shaikh if you want to understand react more deeply. 👉 Read the previous post - Understanding diffing algorithm: https://lnkd.in/dzW3NP_V #SoftwareEngineering #ReactJS #WebDevelopment #JavaScript #FrontendDevelopment #BuildInPublic #LearnInPublic #ReactUnderTheHood

One mistake I kept making while learning React was overusing useEffect. Any time I needed to update something based on state, my first instinct was: Let’s just add an effect for this. It worked at first… until my components started behaving in weird ways: • state updating twice • unexpected re-renders • and once, an infinite loop that took me way too long to debug That’s when I realised something important: useEffect is not for managing normal component logic — it’s for side effects. Now, before writing an effect, I ask myself: Am I syncing with something outside React, or am I just calculating data? If it’s just data, I compute it directly or use useMemo if it’s expensive. This one small change made my React code: simpler, easier to read, and way less buggy. Still learning, but moments like these really changed how I think about React. #reactjs #javascript #frontend #webdevelopment #reacthooks

🚀 Just checked out Vite 8 + AI… and honestly, it feels crazy fast. At first, I used to think Vite was just another dev server. But after exploring it more, it’s actually way more powerful. Here are a few things I noticed 👇 ⚡ Builds feel much faster — even big projects start quickly 🧠 Dependency handling seems smoother (less random issues 😅) 📦 SSR support is better now, which is pretty cool 🔌 Plugins are improving and easier to work with 🛠️ Overall dev experience feels cleaner and less frustrating 💻 One thing I really liked: Frontend errors now show directly in the VS Code terminal (Browser Forward Console). Earlier I had to check the browser console, but now everything is in one place — makes debugging much easier. 📂 Also, TypeScript path aliases are supported better now. No more messy imports like ../../components — cleaner and easier to manage. 💭 What I liked the most: Hot reload + fast builds = less waiting, more coding. Still exploring it, but Vite 8 definitely feels like a solid upgrade. If you're working with React, Vue, or modern JS — you might want to give it a try. Has anyone else tried Vite 8 yet? What do you think? #Vite #Frontend #JavaScript #WebDev #React #Vue

🚀 Understanding Hooks in React (Simple Explanation) When I first started learning React, I thought state management was only possible with class components… but then I discovered Hooks — and everything changed. 👉 Hooks are special functions in React that allow functional components to use features like state and lifecycle methods. 💡 Example: With useState, we can easily manage state inside a function component — no need for classes anymore. Why Hooks are powerful: ✔ Cleaner and more readable code ✔ Reusable logic across components ✔ Less boilerplate compared to class components ✔ Makes development faster and more scalable Some commonly used Hooks: 🔹 useState – manage state 🔹 useEffect – handle side effects (API calls, timers) 🔹 useRef – access DOM elements 🔥 One simple line: Hooks = extra powers for functional components. Learning Hooks really changed how I write React code — and made development feel much more intuitive. #ReactJS #WebDevelopment #Frontend #JavaScript #LearningInPublic #Developers

Just shared a new article on Medium about React Custom Hooks! 🚀 As React developers, we often struggle with bloated components. Custom Hooks are a game-changer for extracting reusable logic and keeping our codebase DRY (Don't Repeat Yourself). In this article, I cover: ✅ What Custom Hooks are ✅ Building a reusable useFetch hook ✅ Best practices for clean code Check it out here: https://lnkd.in/g2Pp46As #ReactJS #WebDevelopment #JavaScript #Programming #Frontend #CodingTips

Why do we specifically pass 'props' into 'super(props)' in a React component constructor? It is one of those things many developers do out of habit without realizing the actual mechanism behind it. While calling 'super()' is a JavaScript requirement to initialize the 'this' keyword, passing 'props' is a very specific React requirement for the constructor phase. The reason is simple: visibility. When you call 'super(props)', you are telling the parent 'React.Component' class to initialize 'this.props' for you immediately. If you only call 'super()' without the argument, 'this.props' will be undefined inside the constructor. React eventually assigns props to the instance anyway, but that happens after the constructor has finished running. If your logic requires you to access a property or compute a state based on a prop right inside the constructor, forgetting the 'props' argument will crash your logic. You would be trying to read from a variable that hasn't been wired up to the instance yet. Even though modern React code bases have shifted to Functional Components where this ceremony is gone, the underlying logic of when data becomes available to an instance is a core part of the library’s history. It is a small detail that perfectly illustrates how React works under the hood. #ReactJS #Javascript #SoftwareEngineering #FrontendDevelopment #WebDev #CodingTips

⚛️ A small mistake in React cost us performance… here’s what happened. Hey devs 👋 We had a dashboard where everything looked fine… until users increased. Suddenly: ❌ UI started lagging ❌ Filters became slow ❌ Re-renders everywhere 👉 The issue? We were passing fresh objects in props on every render. Something like this: <Child data={{ value: count }} /> Looks harmless… right? 💥 But every render = new object reference → child re-render 💡 What fixed it: ✔ Memoizing data with useMemo ✔ Avoiding inline object creation ✔ Using React.memo properly ⚡ Lesson: React doesn’t compare values… it compares references. Small mistakes → big performance issues. Have you ever faced unnecessary re-renders like this? #reactjs #frontend #performance #javascript #webdevelopment #fullstack #softwareengineering #Coding #TechCareers #Programming #success

By default, React is fast. But as data grows, unnecessary re-renders quietly kill performance. Today I learned two hooks that every serious React developer needs to know: 🗒️ useMemo — A cache for heavy calculations. Instead of re-running expensive logic on every render, React stores the result and reuses it. Think of it like a sticky note your genius friend writes so they don't have to solve the same problem twice. 🔗 useCallback — Stabilizes your functions. In JS, functions are objects — so a "new" one gets created on every render. This hook keeps the reference the same, stopping child components from re-rendering for no reason. The senior wisdom I picked up today? Don't over-optimize. These hooks cost memory. Only reach for them when you actually see a lag — not before. Understanding when to optimize is what separates professional developers from the rest. Tomorrow: I'm building my own tools with Custom React Hooks! 👀 Question for you: Do you optimize as you go, or wait until something feels slow? Drop your strategy below 👇 #CodeWithWajid #ReactJS #WebDevelopment #100DaysOfCode #LearningToCode #BuildingInPublic #ReactOptimization #WebPerf