JavaScript Closures: Functions with Memory

For a long time, I treated #JavaScript polyfills as “that config Babel/Webpack handles somewhere in the build pipeline”. Nice to have, not my problem. Then you ship a feature that uses fetch, Promise, or Array.includes… and a user on an older browser starts seeing a blank screen and a cryptic error in the console. That’s basically what polyfills are about for me now: making sure my “modern” code doesn’t silently exclude people with slightly outdated setups. A polyfill is just a small piece of JS that fills a missing feature so older environments can understand APIs newer engines take for granted. Why it’s worth actually understanding them (and not just ticking a checkbox in a bundler): - You write modern code with less fear. Things like Promise, fetch, startsWith, includes feel safe when you know exactly how your app behaves where they don’t exist. - You stop guessing about “browser support”. You can look at a feature, ask “what happens if this is missing?”, and decide: feature detection + polyfill, or a different approach. - You care about the invisible users. Not everyone is on the latest Chrome. Polyfills are a boring but important way of saying “you still get a working experience”. You don’t have to write every polyfill by hand. Libraries like core-js, build tools, and MDN examples cover the heavy lifting. But at least once, it’s worth writing a tiny one yourself (for something like Array.includes) just to feel how it works under the hood. #FrontendDevelopment #WebDevelopment #SoftwareEngineering #Programming #Coding #Opportunity

Are you accidentally slowing down your JavaScript applications? It’s a common mistake I see in code reviews (and one I’ve made myself). When dealing with multiple independent asynchronous calls, it feels natural to just await them one by one. But as the image on the left illustrates, this creates a "waterfall" effect. Your code has to wait for the first operation to finish before it can even start the second one. ✅ The Better Way: Parallel Execution The solution, shown on the right, is Promise.all(). This function takes an array of promises and fires them off simultaneously. Instead of waiting for the sum of all request times (e.g., 2s + 2s = 4s), you only wait for the slowest single request (e.g., max(2s, 2s) = ~2s). This simple change can drastically improve the performance and user experience of your application. A quick rule of thumb: If the data from request A isn't needed to make request B, they should be running in parallel. Have you caught yourself making this mistake? What’s your favorite JS performance tip? Let me know in the comments! 👇 #JavaScript #WebDevelopment #FrontendDeveloper #CodingTips #SoftwareEngineering #PerformanceOptimization

Are you accidentally slowing down your JavaScript applications? It’s a common mistake I see in code reviews (and one I’ve made myself). When dealing with multiple independent asynchronous calls, it feels natural to just await them one by one. But as the image on the left illustrates, this creates a "waterfall" effect. Your code has to wait for the first operation to finish before it can even start the second one. ✅ The Better Way: Parallel Execution The solution, shown on the right, is Promise.all(). This function takes an array of promises and fires them off simultaneously. Instead of waiting for the sum of all request times (e.g., 2s + 2s = 4s), you only wait for the slowest single request (e.g., max(2s, 2s) = ~2s). This simple change can drastically improve the performance and user experience of your application. A quick rule of thumb: If the data from request A isn't needed to make request B, they should be running in parallel. Have you caught yourself making this mistake? What’s your favorite JS performance tip? Let me know in the comments! 👇 #JavaScript #WebDevelopment #FrontendDeveloper #CodingTips #SoftwareEngineering #PerformanceOptimization

“JavaScript is easy.” Until this happens… 🤐 console.log(1 + "11") 👉 111 😵 Wait… what? Here’s what’s happening 👇 In JavaScript, the `+` operator does TWO jobs: ➕ Math addition ➕ String concatenation If one operand is a string, JavaScript silently converts the other one into a string too. So: 1 + "11" becomes "1" + "11" = "111" This is called **Type Coercion** (implicit conversion). 🔄 And that’s just the beginning… JavaScript also has something called - Truthy & Falsy values 👇 Falsy values (remember: FUNN0""): ❌ false ❌ undefined ❌ null ❌ NaN ❌ 0 ❌ "" (empty string) Everything else? ✅ Truthy. That’s why: if ("0") { console.log("Runs") } 👉 It runs 😅 Because "0" is a string — and it's truthy. JavaScript isn’t hard. But it’s full of silent behavior that can trick you. Have you ever been stuck because of type coercion? 👇 Comment your weirdest JS bug. #JavaScript #WebDev #Frontend #CodingTips #JSLearning

Most beginners jump straight to frameworks like React. I chose to go back to basics with vanilla JavaScript instead. 🧠 I built a Stories app using HTML, CSS & JavaScript (ES5) — not for show, but to strengthen my core fundamentals. No libraries. No shortcuts. Just logic, structure and pure JavaScript. This project helped me sharpen: • DOM manipulation • Event handling • Managing UI state • Writing cleaner, structured ES5 code • Understanding user interactions Sometimes the fastest way forward is to go back to the roots. Master the fundamentals, and frameworks become easier. 👉 Curious to know: What core concept should every frontend developer master before moving to frameworks? 🔗 Live Demo: https://lnkd.in/gSmm2N_g 📂 GitHub: https://lnkd.in/gRVcS5vq #BuildInPublic #JavaScript #FrontendDeveloper #WebDevelopment #LearningJourney #100DaysOfCode #Coding

🔒 JavaScript Closures — Explained Simply Closures can feel intimidating when you first hear about them. But the truth is—you’re probably already using them in real projects without even noticing. 📱 Think of a closure like a contact saved on your phone. The call may end, but the number stays stored. 🎒 Or imagine a backpack. Anything you put inside travels with you—just like a closure carries its variables wherever it’s used. 👉 In JavaScript, a closure happens when an inner function keeps access to variables from its outer scope, even after that outer function has finished executing. 💡 This is why closures are so useful: • Preserving state • Encapsulating and protecting data • Writing cleaner and more reliable code ⚡ You’ll commonly encounter closures in event listeners, callbacks, and React hooks—even if you’re not consciously thinking about them. #javascript #closures #webdevelopment #beginners #codingjourney

React stale state is not a bug. It’s us (and closures). I used to think React was “randomly” giving me old state. Turns out, it wasn’t React at all. In JavaScript, when a function is created, it freezes the values around it. That’s a closure. Whatever the state was at that moment — that’s what the function remembers. React just makes this more obvious. Every render creates a new version of your functions. But if you write useEffect(() => { ... }, []), you’re basically saying: “Hey React, keep using the first version forever.” So yeah — your effect runs, your handler fires… but it’s talking to state from the past. That’s the “stale closure” everyone trips over. For years we’ve dealt with this by: tweaking dependency arrays throwing values into useRef or just disabling the linter and moving on Recently, I’ve been liking the direction of useEffectEvent — it lets an effect run when it should, but still read the latest state without hacks. Big takeaway for me: If your hook is ignoring dependencies, it’s not optimized — it’s just outdated. Curious how others are handling this in real codebases 👇 Still useRef, or trying newer patterns? P.S : For more information on this topic , please read out my blog at medium https://lnkd.in/gDY6ZSgf #React #JavaScript #Frontend #Engineering

Is JavaScript actually "easy"? 🔍 The honest answer? It’s easy to start, but hard to master. 🚀 JavaScript is the ultimate "low floor, high ceiling" language. While you can see results in minutes, the deeper you go, the more you realize it’s a massive powerhouse that blends: ✅ Multiple Paradigms: Functional, Procedural, and Class-based programming. ✅ Total Versatility: It powers Web, Mobile, Desktop, and Servers. ✅ Professional Complexity: Moving into Node.js or TypeScript adds layers of architecture that go far beyond the basics. It’s a "jack-of-all-trades" that demands constant growth. You don't just learn JavaScript; you evolve with it. 📈 To the devs out there: When did you realize JS was "deeper" than you first thought? Let's discuss below! 👇 #JavaScript #Coding #WebDev #TypeScript #SoftwareEngineering

❓ Ever wondered why JavaScript sorts numbers “wrong”? Try this: [1, 10, 2].sort() Output: [1, 10, 2] Wait… why not [1, 2, 10]? 🤯 🧠 The reason: By default, JavaScript’s .sort() converts numbers into strings and sorts alphabetically. So it compares: "1", "10", "2" And "10" comes before "2". Sneaky default behavior 👀 ✅ The fix: arr.sort((a, b) => a - b) Now JS knows it’s numeric sorting. Tiny detail. Big difference. Sometimes bugs aren’t errors — they’re misunderstood defaults 😌 #JavaScript #WebDevelopment #CodingJourney #Frontend #Developers

Why #JavaScript Logic Confuses Even Developers 🧠💥 JavaScript is powerful... but it loves to surprise you. Here's why: Type Coercion Magic ✨ "11" + 1 // "111" "11" - 1 // 10 •means string concatenation •forces number conversion Same values, wildly different results! +"" // 0 +{} // NaN +[] // 0 Loose vs Strict Equality ⚖️ 0 == "0" // true 😱 0 === "0" // false ✅ Truthy & Falsy Surprises 🤯 Boolean("0") // true Boolean([]) // true Boolean({}) // true Boolean(0) // false JavaScript auto-converts types to be "helpful"... but that flexibility breeds bugs. How Pros Avoid This (React Dev Edition) 🚀 • Always use === over == • Convert explicitly: Number(), String(), Boolean() • Ditch implicit coercion • Switch to TypeScript for type safety in your React/Next.js apps JS isn't broken—it's just too flexible. Save this cheat sheet! 📌 Comment "JS" if you've been bitten by this. 👇 #JavaScript #WebDevelopment #ProgrammingHumor #CodingLife #Frontend #Developer #codingirlben #React #DeveloperLife #ReactJS #CodingMemes #DevHumor