JavaScript's structuredClone() for Deep Copying Objects

Every JavaScript developer has shipped this bug: async function processStream(response) {  const reader = response.body.getReader()  while (true) {   const { done, value } = await reader.read()   if (done) break   processChunk(value) // ← throws an error  }  reader.releaseLock() // ← never reached. Stream locked forever. } The fix? A try...finally block you have to remember to write every single time. ES2026's using keyword makes this class of bug impossible. 🔒 using readerResource = {  reader: response.body.getReader(),  [Symbol.dispose]() { this.reader.releaseLock() } } // releaseLock() called automatically — even if processChunk throws Add [Symbol.dispose]() to any class, and using guarantees cleanup when scope exits — on return, on break, or on error. For async resources, await using + [Symbol.asyncDispose] handles it: await using redis = new RedisClient(config) // redis.quit() runs automatically when scope exits The proposal also ships: → DisposableStack — manage multiple resources, disposed LIFO → SuppressedError — preserves both errors if cleanup itself throws → Works in for loops — dispose at end of each iteration TypeScript has supported it since 5.2. Chrome 134+, Firefox 134+, Node.js 22+. Babel transpiles it for older targets. I wrote the complete guide for DB connections, transactions, streams, WebSockets, mutexes, perf timers, and DisposableStack patterns. Have you started using this yet? 👇 #JavaScript #ES2026 #WebDev #NodeJS #Programming #100DaysOfBlogging

🧪 Memory Leak Laboratory an open-source tool for JavaScript/TypeScript developers One of the most common reasons a Node.js app slows down over time with no obvious cause is a memory leak hiding inside the code we write every day. A friend and I built js-leak-lab as a hands-on learning tool, not just another article you read and imagine your way through. What you can do in this lab 🔬 • Simulate 20 memory leak patterns unbounded arrays, closures holding references longer than they should, event listeners that never get removed, and more • Toggle leaks on and off instantly and watch the heap spike in real time • Compare Bad Code vs Good Code side-by-side, with both actually runnable • Monitor heap, RSS, and external memory through live gauges and charts updated via WebSocket ⚙️ Stack: Bun + Bun.serve(), Tailwind CSS, Chart.js, Prism.js no frontend build step, open it and it just works 🐳 Docker-ready with memory limit support since this lab simulates real leaks, setting a RAM cap is strongly recommended Built for developers who want to understand how memory leaks actually happen and how to fix them correctly before production figures it out for you. 🔗 GitHub: https://lnkd.in/gRTGUq2C 🌐 Demo: https://lnkd.in/gtjBDp9a #JavaScript #TypeScript #OpenSource #WebDevelopment #NodeJS #MemoryLeak #Bun #DevTools

A single search bar can accidentally send dozens of API requests. Day-12 of building in public I recently learned how a small JavaScript technique called debouncing helps solve this. Imagine a user typing in a search field. Without debouncing, every keystroke can trigger a request to the server. If someone types quickly, the application might send many unnecessary API calls. Debouncing introduces a small delay before executing the function. If the user keeps typing, the timer resets — and the function only runs after the user stops typing. This means instead of multiple requests, the server receives only one meaningful request. A simple concept, but it can significantly improve performance and make applications more efficient. Sometimes small techniques make a big difference in how applications behave. #javascript #webdevelopment #frontenddevelopment #learninginpublic #SheryiansCodingSchool

I got confused by JavaScript data types in my early days. Spent hours debugging a bug that made no sense. Turned out I was comparing two objects and expecting them to be equal. They weren't. Same data. Same structure. But JavaScript said — not equal. That day I learned the difference between primitive and reference types. And honestly? It changed the way I write code. Here is what I wish someone had told me earlier: Numbers, strings, booleans — these are primitives. They store the actual value. Copy them, and you get a fresh copy. Objects and arrays — these are reference types. They store a pointer to memory. Copy them, and both variables point to the same place. That is the bug I had. I was comparing pointers, not values. 13 years later I still think about this when reviewing code. Swipe through the carousel. I made it as simple as possible. If it helps even one developer avoid that same confusion, the job is done. What was your most confusing JavaScript moment? Drop it below 👇 #JavaScript #Frontend #WebDevelopment #ReactJS #NextJS #JS #Programming #LearningInPublic #FrontendDeveloper #WebDev #100DaysOfCode #CodeNewbie #TechTips #SoftwareEngineering

JavaScript introduced its 𝗯𝗶𝗴𝗴𝗲𝘀𝘁 𝘂𝗽𝗴𝗿𝗮𝗱𝗲 after ECMAScript 2015... The alternative to the broken DATE object. Introducing the 𝗧𝗲𝗺𝗽𝗼𝗿𝗮𝗹 object. According to MDN Docs: "𝘐𝘵 𝘪𝘴 𝘥𝘦𝘴𝘪𝘨𝘯𝘦𝘥 𝘢𝘴 𝘢 𝘧𝘶𝘭𝘭 𝘳𝘦𝘱𝘭𝘢𝘤𝘦𝘮𝘦𝘯𝘵 𝘧𝘰𝘳 𝘵𝘩𝘦 𝘋𝘢𝘵𝘦 𝘰𝘣𝘫𝘦𝘤𝘵." Here is how it is differant than the Date object: - Finally Month will start from 1 in JS.  `𝗧𝗲𝗺𝗽𝗼𝗿𝗮𝗹.𝗣𝗹𝗮𝗶𝗻𝗗𝗮𝘁𝗲.𝗳𝗿𝗼𝗺({𝘆𝗲𝗮𝗿: 𝟮𝟬𝟮𝟲, 𝗺𝗼𝗻𝘁𝗵: 𝟰, 𝗱𝗮𝘆: 𝟱}).𝘁𝗼𝗟𝗼𝗰𝗮𝗹𝗲𝗦𝘁𝗿𝗶𝗻𝗴("𝗲𝗻-𝗨𝗦", { 𝗺𝗼𝗻𝘁𝗵: "𝗹𝗼𝗻𝗴" })` The output will be '𝗔𝗽𝗿𝗶𝗹', not May. - Strict Comparisons: To avoid JavaScript's typical "relaxed" type quirks, Temporal includes specific 𝗰𝗼𝗺𝗽𝗮𝗿𝗲 𝗮𝗻𝗱 𝗲𝗾𝘂𝗮𝗹𝘀 𝗔𝗣𝗜𝘀. - 𝗠𝘂𝗹𝘁𝗶𝗽𝗹𝗲 𝗰𝗮𝗹𝗲𝗻𝗱𝗮𝗿 𝘀𝘂𝗽𝗽𝗼𝗿𝘁, beyond the standard Gregorian (ISO 8601) calendar. - `𝗧𝗲𝗺𝗽𝗼𝗿𝗮𝗹.𝗡𝗼𝘄.𝗶𝗻𝘀𝘁𝗮𝗻𝘁()` returns the epoch time with nanosecond precision along with milliseconds, while `𝗗𝗮𝘁𝗲.𝗻𝗼𝘄()` only provides milliseconds. Although Temporal has reached Stage 4 of the TC39 proposal process and is supported in browsers like Google Chrome, Microsoft Edge, and Mozilla Firefox, support in Safari is still pending. Another significant point is that Temporal’s core logic is implemented in a Rust library called 𝘁𝗲𝗺𝗽𝗼𝗿𝗮𝗹_𝗿𝘀. This marks the first time the V8 JavaScript Engine—traditionally written in C++—is incorporating Rust code. Have you tried the Temporal API yet?

JavaScript in 2026: The Dev Update You Didn't Know You Needed ECMAScript continues to evolve, and this year's updates are particularly noteworthy for JavaScript developers. Here’s a comprehensive overview of what’s new, what’s on the horizon, and why it matters. 1. Temporal API — The Biggest JS Feature in Years (ES2026) Date handling in JavaScript has faced challenges since 1995. With the Temporal API, that’s changing. const now = Temporal.Now.zonedDateTimeISO("Asia/Kolkata"); console.log(now.toLocaleString()); // Correct. Always. 2. using keyword — Automatic Resource Cleanup (ES2026) This feature simplifies resource management in asynchronous functions. async function saveData() {   await using file = new FileHandle("output.txt");   await file.write("hello");   // file auto-closed here, even on error } No more worries about forgetting to close database connections or file handles. The runtime ensures cleanup when the variable goes out of scope, which is a significant improvement for server-side Node.js development. 3. Iterator Helpers — Lazy Evaluation (ES2025) This update enhances efficiency by allowing lazy evaluation without creating extra arrays. // Old way: creates 3 new arrays array.map(x => x*2).filter(x => x>10).slice(0, 3); // New way: zero extra arrays, stops after 3 Iterator.from(array).map(x => x*2).filter(x => x>10).take(3).toArray(); This feature works seamlessly with Sets, Maps, Generators, and any iterable, improving performance and memory usage. Additional updates include: - Array.fromAsync() — Collect async generator results into an array effortlessly - Iterator.concat() — Lazily iterate across multiple pages/sources - Error.isError() — Reliably detect real Error #JavaScript #ECMAScript2026 #WebDevelopment #TypeScript #FrontendDev #NodeJS #Programming #SoftwareEngineering #TechNews #CodingLife

🔔 JavaScript’s was written in 10 days in 1995. It took 9 years to fix it dates handling. After nearly 3 decades of broken date handling, JavaScript finally has a proper datetime API — and it just reached Stage 4 (ES2026). Here’s what was wrong with Date and why Temporal changes everything 👇 The problems with Date were real: → Mutable by default (easy to accidentally change a date you didn’t mean to) → Month arithmetic silently rolls over (Jan 31 + 1 month = March 2, not Feb 28) → Ambiguous string parsing that behaved differently across browsers → No native timezone or calendar support Date was literally a port of Java’s 1995 implementation. Rushed. Pragmatic. Never updated. The ecosystem patched it with libraries — but at a cost. Moment.js, date-fns, Luxon. Over 100 million weekly downloads combined. Every project shipping timezone data it may not even need. Bundle sizes bloated. Problems never truly solved. Temporal is the fix: ✅ Immutable — no more accidental mutations ✅ Multiple types (ZonedDateTime, Instant, PlainDate, Duration…) for different use cases ✅ First-class timezone and calendar support ✅ Nanosecond precision ✅ DST-aware arithmetic It’s already shipping: — Chrome v144 ✓ — Firefox v139 ✓ — Edge v144 ✓ — TypeScript 6.0 Beta ✓ 9 years. Champions from Bloomberg, Microsoft, Google, Mozilla, and Igalia. 4,500+ test cases. A shared Rust library (temporal_rs) that multiple engines use together. This is what it looks like when the web ecosystem gets something right. Huge respect to everyone who pushed this across the finish line.

🚀 Memory Management in JavaScript Most developers ignore this… until their apps start lagging 😵 Let’s understand it simply 👇 🧠 What is Memory Management? 👉 How JavaScript stores and cleans memory automatically 👉 Handled by the JavaScript engine ⚡ Memory Lifecycle: 1️⃣ Allocation 👉 Memory is allocated when variables are declared 2️⃣ Usage 👉 You read / write data 3️⃣ Release 👉 Unused memory is removed 🗑️ Garbage Collection (GC) 👉 JavaScript automatically removes unreachable memory 💡 Based on: 👉 Reachability ✔ Reachable = In use ❌ Not reachable = Garbage 🧩 Example: let user = { name: "Swapnil" }; user = null; // Now object becomes unreachable 👉 Memory is cleaned automatically 🔥 Common Memory Leaks: ❌ Unused global variables ❌ Forgotten timers (setInterval) ❌ Closures holding unnecessary data ⚡ Why it matters? 👉 Prevents: ✔ Memory leaks ✔ Slow apps ✔ Crashes 💡 One line to remember: 👉 “If nothing references it, JavaScript removes it” 💬 Did you know JavaScript handles memory automatically? 📌 Save this (advanced + interview important) #javascript #webdevelopment #frontend #coding #programming #javascriptdeveloper #learncoding #developers #100DaysOfCode

Small JavaScript bugs keep escaping to production and breaking critical user flows. Debugging inconsistent runtime behavior steals time from feature delivery. ────────────────────────────── Unlocking the Power of Proxy and Reflect in JavaScript Let's dive into the Proxy and Reflect APIs in JavaScript and how they can enhance your coding skills. #javascript #proxy #reflect #webdevelopment ────────────────────────────── Core Concept Have you ever wished you could intercept and customize operations on objects? The Proxy and Reflect APIs might be just what you need! They allow you to define custom behavior for fundamental operations (like property lookup and assignment) on objects. Are you ready to explore how they work? Key Rules • Proxies can intercept operations on objects (e.g., get, set). • Reflect provides methods to operate on objects directly, making it easier to manipulate them. • Both tools enable more dynamic and robust code, reducing boilerplate. 💡 Try This const target = { name: 'Alice' }; const handler = { get: (obj, prop) => Hello, ${obj[prop]}! }; const proxy = new Proxy(target, handler); console.log(proxy.name); // Outputs: Hello, Alice! ❓ Quick Quiz Q: What is the primary purpose of using a Proxy in JavaScript? A: To define custom behavior for fundamental operations on objects. 🔑 Key Takeaway Leverage Proxy and Reflect to write cleaner, more powerful JavaScript code!

A tale of two JavaScript patterns and the bugs that catch you out 🐛 I've been revisiting the two main ways to create custom objects in JavaScript. Both achieve the same goal. Both have traps. Here's what I found: ES6 Class class Character { constructor(name) { this.name = name this.powers = [] } addPowers(power) { this.powers.push(power) console.log(`${this.name} has ${this.powers} Powers!`) } } Methods live outside the constructor, inside the class body. They land on the prototype automatically so every instance shares one copy rather than each carrying its own. Constructor Function function Character(name) { this.name = name this.powers = [] this.addPowers = function(power) { this.powers.push(power) console.log(`${this.name} has ${this.powers} Powers!`) } } Easy gotcha: write function addPowers() instead of this.addPowers = and the method becomes a private inner function completely invisible outside the constructor. Your code won't error on creation, it'll just silently fail when you try to call it. The class syntax is cleaner and harder to get wrong. But understanding constructor functions teaches you what's actually happening under the hood and makes legacy codebases far less scary. Worth noting: there is a third way Object.create() but I've not covered it here. It gives you very fine-grained control over the prototype chain, but it's significantly more verbose and rarely the first tool you'd reach for. Both patterns. Both worth knowing. Have you been caught out by either of these? Let me know below 👇 #JavaScript #WebDevelopment #CodingTips #OOP #LearnToCode #JSDevs #SoftwareEngineering