How to avoid business logic in React components and improve testability.

React architecture changed more in 18 months than in the previous 8 years. Here’s what actually works at scale in 2025 (learned the hard way): Adopt (server-first by default) • Server Components for data + heavy libs; push ‘use client’ to the leaves • TanStack Query for server state; Zustand or RTK for client/UI state • Three layers: Presentation (pure UI) → Application (hooks + pure funcs) → Services (IO) • Next.js 15 patterns: nested layouts, Suspense streaming, Server Actions • TypeScript everywhere, Tailwind (optionally shadcn/ui) for sane velocity Avoid (these collapse under growth) • Business logic inside components/hooks (test-hostile, not reusable) • God Context that re-renders the world on every change • Overusing effects for data fetching/mutations that belong on the server • Premature folder complexity before you hit real pain Principles that keep teams fast • If it doesn’t need state/effects/DOM, make it a pure function (DI for testability) • Feature-based folders past ~50 components; clear ownership boundaries • Caching is explicit; measure bundle size + CWV, not vibes Testing that actually pays off • 60–70% unit tests (pure funcs) • 20–30% integration (RTL) • 5–10% E2E (Playwright) on revenue-critical flows Result: smaller bundles, faster first paint via streaming, simpler tests, and code you can move between web and mobile without rewrites. #ReactJS #Nextjs #ServerComponents #TypeScript #WebDevelopment

React’s New use() Hook Simplifies Async Data Handling. React just introduced a game-changing API, the use() hook, designed to make asynchronous data fetching and server component integration seamless. What it does: - Lets you “unwrap” promises directly inside components - Removes the need for useEffect, loading states, or extra state hooks - Works hand-in-hand with Suspense and Server Components - Simplifies async rendering with cleaner, synchronous-style code No extra effects, no manual state management. React now handles suspension, hydration, and error recovery natively. The use() hook signals a philosophical shift in React’s architecture: async rendering is no longer an afterthought, it’s built into the core model. What do you think? Is this the end of useEffect for data fetching? #React #JavaScript #WebDevelopment #Frontend #Async #Suspense #ReactServerComponents #RomanFedytskyi

Ever find yourself writing the same data-fetching logic in multiple React components? It's a classic code smell. I used to copy-paste my `useEffect` with `fetch` and state management (`useState` for data, loading, error). It was messy and hard to maintain. 😫 Then I discovered the power of custom hooks. 💡 By encapsulating that logic into a single `useFetch` hook, I cleaned up my components drastically. Now, instead of 15 lines of boilerplate, it's just one: `const { data, loading, error } = useFetch('/api/users');`. It makes the logic reusable, testable, and keeps components focused on the UI. 🚀 𝐀𝐛𝐬𝐭𝐫𝐚𝐜𝐭 𝐲𝐨𝐮𝐫 𝐫𝐞𝐩𝐞𝐭𝐢𝐭𝐢𝐯𝐞 𝐥𝐨𝐠𝐢𝐜 into custom hooks. Your future self will thank you. What small change made a huge impact in your workflow? #ReactJS #FrontendDevelopment #DeveloperTips

⚡ Advanced Web Performance Debugging: From HAR to Insights After solving a 10-second record loading delay in my Node.js app, I dove deeper into Chrome DevTools to refine my troubleshooting workflow. Here are 10 powerful techniques that go beyond the basics — perfect for any developer or IT engineer dealing with performance issues on production systems 👇 ⸻ 🔍 1️⃣ Use “Waterfall” Spot sequential API calls and use Promise.all() for parallel execution. 🔗 2️⃣ Check the “Initiator Chain” Find which script or component triggers slow requests. 📦 3️⃣ Watch Response Sizes Enable compression, paginate APIs, and optimize images. 🧠 4️⃣ Check Browser Main Thread Activity Identify heavy JavaScript tasks or re-renders blocking UI. ⏱️ 5️⃣ Look for “Long Tasks” Break code into smaller chunks to avoid >50ms blocking. 🧩 6️⃣ Use “Coverage” Tab Locate unused JS/CSS to reduce unnecessary load. 🛡️ 7️⃣ Evaluate Caching Set proper Cache-Control headers for static assets. 📈 8️⃣ Compare TTFB vs. Total Time Pinpoint whether backend latency or payload size is the culprit. 💡 9️⃣ Run Lighthouse Audit Quickly assess performance scores and key web vitals. ⚙️ 🔟 Automate Measurement Use CrUX or PageSpeed API for continuous real-world tracking. ⸻ 💬 Key takeaway: Don’t rely on assumptions — every second of delay has a traceable cause. HAR files, performance profiles, and DevTools insights reveal exactly where your app struggles and how to fix it. ⸻ #NodeJS #Azure #WebPerformance #DevTools #FullStack #WebOptimization #CloudEngineering #WebDev #ITPerformance

It’s time to decide the tech stack, which can make our #ERP development possible. See, our ERP will work on 3-tier architecture. It has following parts: 1. Frontend (UI/UX things) 2. Backend (API and Business Logics) 3. Database (statefulness)   Starting from FRONTEND, we will use: 1. NextJs – because it provides modern day workflows, UI/UX libraries (such as ShadCN UI) are written on it and easily deployable to Vercel. 2. Tailwind CSS and ShadCN UI – for ready to use NextJs Components 3. TypeScript – for being compile first, type checking and highly used.   BACKEND part is in: 1. FastAPI – for API development with minimal lines of code. 2. Pydantic – for type checking of input to a function 3. SQL Model – for communication with our Database   DATABASE is in: 1. MariaDB – as it is RDBMS, faster than MySQL and has sufficient features making it lightweight rather than being heavy weight as PostgreSQL (no offences to MySQL and PostgreSQL community ✌🏻)   APART from THIS! 1. Git – for version control in branches and commits 2. GitHub – for remote location to dump my code, which I will later push to production 3. Docker by Docker, Inc – for containerized development of my code, so I will have independent containers to work with code, and gives idea about networking among them. 4. Adminer – a minimal, but powerful Database visualizer 5. Postman – for API testing 6. Visual Studio Code - as a Code Editor

𝗪𝗮𝗻𝘁 𝘁𝗼 𝗳𝗲𝘁𝗰𝗵 𝗱𝗮𝘁𝗮 𝘄𝗶𝘁𝗵𝗼𝘂𝘁 𝗯𝗹𝗼𝗰𝗸𝗶𝗻𝗴 𝘆𝗼𝘂𝗿 𝗨𝗜? 𝗧𝗿𝘆 𝗥𝗲𝗮𝗰𝘁 𝗦𝘂𝘀𝗽𝗲𝗻𝘀𝗲! Suspense lets you "wait" for async operations (like data fetching) without blocking the entire UI. No more loading spinners that freeze your app! How it works: → Wrap your async component with 𝗥𝗲𝗮𝗰𝘁.𝗦𝘂𝘀𝗽𝗲𝗻𝘀𝗲 → Use a "fallback" component (e.g., a spinner or skeleton screen) while data is loading → Once data is ready, React automatically swaps in the fully loaded component Benefits: • Improved user experience—only the relevant part of the UI waits for data • Cleaner code—no more manual loading states or conditional rendering • Seamless integration with React Query, SWR, or other data-fetching libraries Example: ``` <Suspense fallback={<Spinner />}> <AsyncComponent /> </Suspense> ``` Tip: Combine Suspense with 𝗥𝗲𝗮𝗰𝘁.𝗹𝗮𝘇𝘆 for even better performance. Load components only when they’re needed! 𝗥𝗲𝘀𝗼𝘂𝗿𝗰𝗲𝘀: • 𝗥𝗲𝗮𝗰𝘁 𝗱𝗼𝗰𝘀: https://lnkd.in/dUpifpQG • 𝗣𝗿𝗮𝗰𝘁𝗶𝗰𝗮𝗹 𝘁𝘂𝘁𝗼𝗿𝗶𝗮𝗹𝘀 𝗼𝗻 𝗦𝘂𝘀𝗽𝗲𝗻𝘀𝗲 + 𝗱𝗮𝘁𝗮 𝗳𝗲𝘁𝗰𝗵𝗶𝗻𝗴 #ReactJS #Suspense #DataFetching #WebDevelopment #JavaScript #Frontend #ReactDev

One of the simplest ways to make React code more reliable — and easier to maintain — is to derive state instead of syncing it. Too often we store values that can be calculated from existing state or props, and then spend extra effort keeping them in sync. That’s where bugs and unnecessary complexity sneak in. Why this matters: - Fewer sync issues: When one piece of state depends on another, it’s only a matter of time before they fall out of sync. - Simpler logic: Less boilerplate, fewer effects, cleaner renders. - Easier maintenance: When your data model changes, you only update it in one place. A good rule of thumb: If you find yourself writing a useEffect whose sole purpose is to keep two state variables in sync — that’s a sign one of them should be derived. This principle applies equally to client-side data and server-fetched data. With tools like TanStack Query, the server state is already your source of truth. Your UI state should be derived from it, not duplicated. Store only what truly needs to persist. Everything else — compute it when you render. Here, 𝐬𝐞𝐥𝐞𝐜𝐭𝐞𝐝𝐈𝐝 doesn’t need its own state — it’s derived from users. #React #Frontend #WebDevelopment #CleanCode #DerivedState

💻 Step 3.5 — Understanding Software Architecture No new endpoints, no new features — this time, I stopped the coding to understand how everything connects. My primary intention with this personal project is to build a dashboard that can easily scale in the future, adding more features (like user accounts and real-time data) without a complete rewrite. That's why diving deep into architecture was non-negotiable. Here’s what I learned about software architecture (even for small projects): ✅ Separation of Concerns (SoC): How dividing the work (Server, API, Database, Frontend) prevents chaos and makes the project scalable. ✅ Architecture vs. Theory: It's a practical guide, not just an abstract concept. Having a "map" of the system brings intention to every development decision. ✅ And that having a map of your system brings clarity to every decision This is my first architecture diagram for Dashboard Bets Core — a high-level view of how the project works so far . It’s not final, but it represents a big step In this diagram, my initial data flow is simple. Which architecture pattern (like MVC or a Layered Design) do you think would be most suitable for the next stage of this Node.js API's growth? I'm reading your suggestions! 👇 #JavaScript #Nodejs #BackendDevelopment #FullStackJourney #SoftwareArchitecture #LearningByBuilding #VanillaJS #BuildInPublic

🚀 Handling Async Data In React Today while building my Customer Segmentation page, I ran into a classic React issue: My child component was getting undefined props… because the data hadn’t loaded yet. Why? React doesn’t wait for data—it renders fast, sometimes too fast for your async calls. The simple fix I used: {Array.isArray(users) && users.map((elem) => (...))} ✅ Render only when data is ready ✅ Prevent runtime errors ✅ Keep your UI stable In larger projects, this problem is usually handled with: -Loading states (spinners, skeletons) ->State management tools like Redux or React Query ->TypeScript to catch undefined/null data ->Error handling for network issues 💡 Takeaway: React renders fast—your data might not. Always handle async safely. Thinking about scalability and stability now makes a huge difference in industrial projects. #ReactJS #FrontendDevelopment #JavaScript #WebDevelopment #CleanCode #CustomerSegmentation #LearningInPublic

**New React Architecture Tutorial in the Gen Z JavaScript Series!** 🌳 To master React, you have to think like React! That means visualizing your application not just as a page, but as a **Component Tree**. In my latest video, "Understanding Your UI as a Tree," we simplify this fundamental concept. Grasping the parent-child hierarchy is the key to: * Successfully managing props and data flow. * Architecting reusable and scalable components. * Debugging state issues efficiently. If you struggle with knowing where to put state or how components relate, this video is a must-watch! **Learn to visualize your UI like a pro:** https://lnkd.in/g6KS27dF Do you always sketch out your component tree before coding? Let me know your workflow! 👇 #ReactJS #ReactArchitecture #ComponentTree #DataFlow #JavaScript #WebDevelopment #GenZJavaScript