When to Use useMemo in React

Why do we need the 𝘂𝘀𝗲𝗠𝗲𝗺𝗼 hook when we can perform heavy calculations inside 𝘂𝘀𝗲𝗦𝘁𝗮𝘁𝗲, which runs only once? The key difference is flexibility and reactivity. 𝘂𝘀𝗲𝗠𝗲𝗺𝗼 can run once or re-run when specific values change. It accepts two arguments: 1. A callback function 2. A dependency array You can pass values in the dependency array, and whenever any of those values change, React re-invokes the callback function. This ensures you always have the latest values inside the callback. Real-world use case: Validating edit form values on initial load and re-validating when certain conditions or inputs change. #ReactJS #FrontendDevelopment #JavaScript #WebDevelopment #ReactHooks #PerformanceOptimization #CodingTips

Day 3 — useEffect ⚡ Why was useEffect even created? Things were working before it too! 🤔 Simple answer: →without it, your API fired on every render → infinite loops & duplicate requests. Use useEffect when: → Fetch data on mount → Subscribe & cleanup events → DOM manipulation → React to dependency changes What's your biggest useEffect mistake? 👇 #ReactJS #useEffect #JavaScript #30DaysOfReact #LearningInPublic

What are Hooks? Hooks are special functions that allow you to use state and lifecycle features inside functional components. 🔹 useState 🧩 Manage and update component data easily without class components. 🔹 useEffect 🔄 Handle side effects like API calls, DOM updates, and subscriptions. 🔹 Why Hooks Matter? ⚡ Cleaner and shorter code 🔁 Reusable logic across components 🚀 Better readability and maintainability #ReactHooks #ReactJS #JavaScript #FrontendDev

useEffect — The Hook That Confused Me (Until I Got This) useEffect was confusing until I understood one thing: dependencies control everything. The Rule: javascript // Runs ONCE after mount useEffect(() => { fetchData(); }, []); // Runs when userId changes useEffect(() => { fetchUser(userId); }, [userId]); // Runs on EVERY render (avoid!) useEffect(() => { console.log('render'); }); What I Learned the Hard Way: Missing dependencies = stale data Adding everything = infinite loops Cleanup functions matter (especially for subscriptions) My Checklist: What should trigger this effect? Do I need to clean up? Can this cause unnecessary renders? What's your React Hook survival tip? #ReactJS #JavaScript #FrontendDeveloper #WebDev #CodingTi

most developers don't understand closures and it breaks their loops. classic problem: everyone uses let now so this fixes itself but the problem is still there, just hidden. here's why it happens: - when you use var > it's function-scoped not block-scoped. - by the time the timeout runs, the loop is done and i is 3. - all three callbacks reference the fix with let: let is block-scoped so each iteration gets its own i . but here's what you should actually know: - this isn't a JavaScript problem. this is a closure problem. - every function closes over the variables around it. - understanding that changes everything about how you debug async code, event listeners, callbacks. stop memorizing the fix. understand why it happens. #javascript #typescript #webdevelopment #buildinpublic #reactjs

I almost forgot how powerful fundamentals are… until I tested myself. I took a short break from work and revisited JavaScript "array.map()". I used it to update the age property inside an array of objects, and it worked perfectly. This is a reminder: consistency beats intensity in tech. Even the basics, when revisited often, become your strongest tools. Still building. Still growing. #JavaScript #SoftwareDevelopment #FrontendDevelopment #WebDevelopment #CareerGrowth #TechCareers #ContinuousLearning

📌 Part 8 of 10: A lot of React bugs make more sense once you realize state behaves more like a snapshot than a live variable. That idea sounds small. But once it clicks, a lot of confusing behavior starts making more sense. Why logs can feel misleading. Why updates don’t look immediate. Why handlers sometimes “see” older values than people expect. Once I really understood that, I stopped fighting React as much. I started designing with it instead. What React concept took longer to click for you than expected? #React #ReactJS #StateManagement #JavaScript #FrontendDevelopment #Debugging #TypeScript

🚀 Day 37 — #useRef() Hook in #React Today I learned about the useRef() Hook in React 🔗 Introduced in React 16.8, useRef() is available in functional components and helps us directly access DOM elements. It works similarly to document.querySelector() in plain JavaScript, but in the React way. ✅ Key Learning useRef() stores a mutable value in .current and updates it without causing a component re-render. 💡 Perfect for DOM access, focus management, timers, and storing previous values. 🔥 Slowly moving deeper into advanced React hooks. #React #useRef #ReactHooks #FrontendDevelopment #JavaScript #10000 Coders

⚠️ Common Confusions about Control Flow : Switch case: switch-case executes all cases after a match unless you break. else if : else if chain works top-down — order matters. You can use truthy/falsy values directly in if . 🧠 Mindset Control flow = conditional storytelling. It helps your program make choices and respond differently to different inputs. Write readable branches. Avoid nesting too deep — use early return if needed.  #react #javascript #JS #ABK #code

useEffect is probably the most powerful - and most misused - hook in React. 🎯 Arun explained it really well, sharing this because I've made  these exact mistakes in real projects: → Forgetting the cleanup function - memory leaks in production 😅 → Wrong dependency array - stale data showing up in dashboards → Fetching data inside useEffect - unnecessary re-renders and   race conditions What changed for me: ✅ Always write cleanup for subscriptions and event listeners ✅ Use React Query for data fetching — avoids most useEffect complexity ✅ Think twice before adding objects/arrays as dependencies 2.5 years of React and useEffect still teaches me something new. What's your most common useEffect mistake? Drop it below 👇 #ReactJS #Frontend #JavaScript #WebDevelopment #FrontendDeveloper