AsyncStorage Mistake in React Native Apps

🚀 Why Your React App Feels Slow (Even If Your Code Looks Fine) You check your code. Everything looks clean. No errors. No warnings. But still… the app feels slow. I’ve faced this in real projects — and the issue is rarely “bad code”. It’s usually hidden performance mistakes 👇 🔹 Too many unnecessary re-renders → Components updating even when data hasn’t changed 🔹 Large components doing too much → One component = multiple responsibilities 🔹 No memoization → Missing React.memo, useMemo, useCallback where needed 🔹 Heavy API calls without optimization → No caching, no batching, no proper loading handling 🔹 Poor state management → Global state changes triggering full re-renders 🔹 No code splitting → Loading everything at once instead of lazy loading 🔹 Unoptimized lists → Rendering large lists without virtualization 💡 What actually improved performance for me: ✔ Breaking components into smaller units ✔ Using memoization strategically (not everywhere) ✔ Lazy loading routes & components ✔ Optimizing API calls (RTK Query caching helped a lot) ✔ Avoiding unnecessary state updates 📌 Reality: Performance issues don’t show in small apps… They appear when real users start using your product. Clean code is good. But optimized code is what users feel. 💬 What’s one performance issue you faced in React? #ReactJS #FrontendPerformance #WebDevelopment #JavaScript #SoftwareEngineering #CleanCode

Here’s something that took me a while to accept… You can build a Next.js app that works perfectly fine. Pages load, data shows up, and users can click around. And yet, you could still be doing it completely wrong. Not wrong in a "this will crash" way. Wrong in a quieter way... The kind of wrong that results in 800 KB JavaScript bundles for a simple landing page. The kind of wrong that creates hidden data waterfalls, making your app feel sluggish despite being "modern." I’ve seen this in countless code reviews. I’ve seen it in projects from senior React devs. And I definitely did it myself. The issue isn’t skill. It’s a mental model problem. Next.js forces you to make decisions that React never asked you to make: Does this component live on the server or the client? Should this data be cached, revalidated, or fetched fresh? Is this a Server Action or an API route? Does it even matter? Spoiler: It’s the difference between a secure app and a data leak. In standard React, everything runs in the browser. In Next.js, every decision changes the architecture of your entire app. Get them wrong, and the app still "works," it just doesn't work the way Next.js was engineered to work. Most developers don’t realize they’re building a "React app inside a Next.js folder" until it’s too late to change. #NextJS #ReactJS #FrontendDevelopment #SoftwareEngineering #JavaScript #FullStackDevelopment #SystemDesign #WebPerformance #CleanCode #BuildInPublic #DeveloperExperience #AppArchitecture

💥 Most developers assume using useMemo and useCallback everywhere will automatically make a React app faster. Sounds logical: Memoize more → fewer re-renders → better performance. But in real-world apps, it often doesn’t work like that. I’ve seen this pattern quite often — developers start adding these hooks with good intent, but without actually measuring anything. • Wrapping functions with useCallback • Memoizing even simple values • Adding optimizations “just in case” And then… 🚨 No real performance improvement 🚨 Code becomes harder to read and maintain 🚨 Debugging gets more complicated 🚨 Sometimes performance even degrades 🧠 The important part: useMemo and useCallback are not free. They introduce overhead — memory usage, dependency comparisons, and extra complexity. ⚡ What actually works better: • Understanding why components re-render • Improving state structure • Splitting components smartly • Measuring performance using React DevTools 🔥 My take: React is already quite fast. Blindly adding memoization often creates more problems than it solves. 💡 Rule I follow: If I haven’t measured a real performance issue, I don’t reach for useMemo or useCallback. Curious — do you think these hooks are overused in most React apps? 🤔 #ReactJS #FrontendDevelopment #WebPerformance #JavaScript #SoftwareEngineering #ReactPerformance

If removing every useMemo and useCallback from your app changes nothing… They were never fixing the problem. 😭 We’ve all done it. App feels slow → immediately add: useMemo(...) useCallback(...) Suddenly we feel like we’ve optimized the app. 🤡 Meanwhile the real problem is still there: • Rendering 5,000 rows • Fetching 2MB of JSON • Re-rendering the whole page • 14 charts fighting for their lives useMemo and useCallback are useful — but only when they solve an actual bottleneck. If deleting them makes no noticeable difference, they were probably just performance-flavored decoration. And since memoization is not free, you may have actually made things slightly slower. 💀 One exception: If a function is passed as a dependency, useCallback can keep the reference stable. But if the function is only used inside the effect, just move it into the effect: // ❌ Unnecessary const fetchData = useCallback(() => fetch('/api/data'), []); useEffect(() => { fetchData(); }, [fetchData]); // ✅ Simpler useEffect(() => { const fetchData = () => fetch('/api/data'); fetchData(); }, []); Most React apps are not slow because of this: onClick={() => setOpen(true)} They are slow because somewhere deep in the codebase there is a component rendering the entire internet on every keystroke. 😭 React’s advice is simple: Profile first. Then optimize. Otherwise you are just making the code harder to read for free. We didn’t optimize the app. We put Flex Tape on a waterfall. 🌊 #ReactJS #JavaScript #WebDev #Frontend #ReactHooks #FrontendDevelopment #SoftwareEngineering #DevHumor #CodeNewbie #100DaysOfCode

🚨 Why Your Node.js App Slows Down Over Time (Hidden Memory Leaks) If your Node.js app starts fast but gets slower over time… you might have a memory leak. 👉 This is a senior-level issue most developers ignore. 🔍 Common causes: ❌ Unremoved event listeners ❌ Global variables growing over time ❌ Caching without limits ❌ Open database connections ❌ setInterval / setTimeout not cleared 💡 Example mistake: Adding event listeners inside a request handler app.get("/", (req, res) => { process.on("event", () => {}) // ❌ memory leak }) Every request adds a new listener → memory keeps increasing 💡 Fix: ✔ Remove listeners when not needed ✔ Use weak references where possible ✔ Monitor memory usage (heap snapshots) ✔ Use tools like: Chrome DevTools clinic.js ⚡ Senior Rule: “If memory keeps growing, your app will eventually crash — it’s just a matter of time.” Don’t just fix bugs… prevent system failure. #nodejs #backend #memoryleak #performance #javascript #webdev #fullstackdeveloper #debugging

🚫 Stop creating instances manually in your Node.js apps. If you're doing this in your code: 👉 const userService = new UserService(); You’re quietly building a trap for your future self. Here’s why. 💥 The Problem: The "Hardcoded" Nightmare Imagine your app has 50 controllers all using new UserService(). Tomorrow, your PM says: "The DB is slow, we need to swap this for a CachedUserService." Without Dependency Injection (DI), you now have to: Open 50 files. Manually change the import and class name in every single one. Hope you didn't break a test. There goes your weekend. --- ✅ The Solution: How NestJS saves you Instead of creating the instance yourself, you just "ask" for it in the constructor: 👉 constructor(private readonly userService: UserService) {} What’s happening behind the scenes? NestJS uses DI to act as a "middleman." You define the wiring in ONE central place (the Module): { provide: UserService, useClass: CachedUserService } Why this is a game-changer: 1️⃣ The 5-Second Swap: Need to change logic? Update one line in the Module. The 50 controllers using it don't need a single change. 2️⃣ Seamless Testing: Want to mock the service for a unit test? Just "inject" a mock version. 3️⃣ Decoupled Code: Your controllers don't care how a service works; they just know it has the methods they need. 📦 Real-world impact: In large systems, DI is the difference between a maintainable architecture and a spaghetti-code disaster. 🎯 One takeaway: If your classes are creating their own dependencies, you're limiting your system’s scalability. Let the framework do the heavy lifting. #NodeJS #NestJS #SoftwareEngineering #CleanCode #WebDevelopment #Backend

How React Native apps talk to your backend — and where it breaks in production. Most React Native tutorials show you the happy path: fetch data, display it, done. Production is different. Here's what actually needs to be handled in your data layer: 1. Network state awareness Don't just check if a request failed — check why. No connection, slow connection, and server error all need different UX responses. 2. Request cancellation If a user navigates away before a request completes, cancel it. Uncancelled requests cause state updates on unmounted components — a common source of memory leaks. 3. Retry logic with backoff Transient failures should retry automatically — but not instantly and not forever. Exponential backoff prevents hammering a struggling server. 4. Token refresh handling Access tokens expire. Your API client needs to intercept 401 responses, refresh the token silently, and replay the original request. If this isn't built, users get logged out randomly. 5. Optimistic updates For actions like liking, saving, or deleting — update the UI immediately, sync in background. Waiting for the server makes apps feel slow. React Query and SWR handle most of this for web. For React Native, React Query works well — or build your own with Axios interceptors if you need more control #ReactNative #MobileDevelopment #JavaScript #APIIntegration #BackendDevelopment #FullStackDevelopment

⚛️ React Devs — Why Your App Feels Slow Even After Optimization? Hey everyone 👋 Ever optimized your React app… used memo, useCallback, useMemo… but it STILL feels slow? Yeah, I’ve been there. 👉 The hidden issue most people ignore: ❌ Too many unnecessary API calls ❌ Waterfall fetching ❌ Blocking UI while waiting for data 💡 What actually fixed it for me: ✔ Parallel data fetching ✔ Suspense + streaming (Next.js) ✔ Moving logic to server components ⚡ Real insight: “Frontend performance is often limited by backend patterns.” 👉 If your UI is slow… check your data flow, not just React code. Curious — what was your biggest React performance bottleneck? #reactjs #nextjs #frontendperformance #webperformance #javascriptdeveloper #fullstackdeveloper #softwareengineering #reactperformance #webdevelopment #frontendarchitecture

Your React App is Slow… and You Might Be the Reason Most developers use useMemo and React.memo but very few actually understand when NOT to use them ⚠️ I recently debugged a performance issue in a React dashboard. Everything looked optimized — but still, the UI was lagging. The reason? 👉 Memoization was used… but used wrongly. ⚡ Let’s break it down simply: 🔹 useMemo — Caches Calculations Use it when you have expensive computations Example: const filteredData = useMemo(() => { return data.filter(item => item.active); }, [data]); ✔ Prevents unnecessary recalculations ❌ Useless for cheap operations 🔹 React.memo — Stops Re-renders Wrap your component to avoid re-render when props don’t change const Card = React.memo(({ item }) => { return <div>{item.name}</div>; }); ✔ Great for large lists / heavy UI ❌ Useless if props change every render 🔥 The Real Problem Most people do this: Wrap everything in React.memo Add useMemo everywhere Hope performance improves 👉 Result: More complexity, same performance (sometimes worse) 💡 What Actually Works ✔ Use useMemo only for heavy calculations ✔ Use React.memo only when re-renders are costly ✔ Avoid passing new object/array references every render ✔ Measure performance before optimizing 🧠 The Mindset Shift Optimization is not about adding hooks It’s about removing unnecessary work 🚀 Final Takeaway Don’t optimize blindly. First understand: Why is it re-rendering? Is it actually slow? Then use the right tool. 👇 Curious — have you ever faced unnecessary re-renders in your app? #ReactJS #FrontendDevelopment #JavaScript #WebPerformance #ReactHooks #SoftwareEngineering #CleanCode #DevTips

⚡ A small Promise.all detail that can break your app Promise.all looks simple. Run multiple async tasks → get all results. But here’s the catch 👇 ❌ If even one promise fails, everything fails So even if 2 APIs succeed and 1 fails… you get nothing 😬 This hit me in a real project 👇 One non-critical API failed, and the entire page broke 💥 What I do now: ✅ Use Promise.all only when all results are required ✅ Use Promise.allSettled when partial data is acceptable Because sometimes… 👉 Partial data > No data Small detail. Real impact. #JavaScript #FrontendDevelopment #WebDevelopment #AsyncJS #SoftwareEngineering