JavaScript 2026 Updates: Temporal API, using keyword, Iterator Helpers and more

TypeScript enums are problematic. Here's what senior developers use instead. Enums look useful. They feel organised. But they introduce real problems in TypeScript projects. The problems with enums: ts// Numeric enums have dangerous reverse mappings enum Direction { Up, Down, Left, Right } Direction[0] // 'Up' — this exists at runtime and causes confusion // Enums are not just a type — they generate JavaScript code // That means your bundle is larger than it needs to be // Const enums cause issues with babel and SWC compilers const enum Status { Active, Inactive } // Can break in certain build configurations What to use instead: Option 1 — Union types (best for most cases) tstype Direction = 'up' | 'down' | 'left' | 'right' // Autocomplete works perfectly // No JavaScript generated // Fully type-safe Option 2 — As const objects (best when you need runtime access) tsconst Status = { ACTIVE: 'active', INACTIVE: 'inactive', PENDING: 'pending', } as const type Status = typeof Status[keyof typeof Status] // Type: 'active' | 'inactive' | 'pending' // You can still do: Status.ACTIVE // 'active' — runtime access works Object.values(Status) // ['active', 'inactive', 'pending'] Why as const objects win: → No extra JavaScript generated → Runtime access when you need it → Works with every build tool → Type is derived automatically → Readable, familiar object syntax Union types for simple cases. as const objects when you need runtime access. Enums — almost never. Were you using enums? What are you switching to? 👇 #TypeScript #JavaScript #FrontendDevelopment #ReactJS #WebDevelopment #CleanCode #SoftwareEngineering

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

Small JavaScript bugs keep escaping to production and breaking critical user flows. Debugging inconsistent runtime behavior steals time from feature delivery. ────────────────────────────── Understanding Type Declaration Files (.d.ts) Ever wondered how to make TypeScript work seamlessly with JavaScript libraries? Let's dive into .d.ts files! #typescript #javascript #development #typedeclaration ────────────────────────────── Core Concept Type declaration files, or .d.ts files, are crucial when working with TypeScript and JavaScript libraries. Have you ever faced issues with type safety while using a library? These files help bridge that gap! Key Rules • Always create a .d.ts file for any JavaScript library that lacks TypeScript support. • Use declare module to define the types of the library's exports. • Keep your declarations organized and maintainable for future updates. 💡 Try This declare module 'my-library' { export function myFunction(param: string): number; } ❓ Quick Quiz Q: What is the main purpose of a .d.ts file? A: To provide TypeScript type information for JavaScript libraries. 🔑 Key Takeaway Type declaration files enhance type safety and improve your TypeScript experience with external libraries!

New ES2023 JavaScript features are 🔥 toSorted(), toSpliced(), toReversed(), with(), findLast(), findLastIndex() help avoid mutation — super useful for React devs. Read here: https://lnkd.in/g9hkhk74 #javascript #react #webdev

JavaScript is easy. Until it isn't. 😅 Every developer has been there. You're confident. Your code looks clean. You hit run. And then: " Cannot read properties of undefined (reading 'map') " The classic JavaScript wall. Here are 7 JavaScript mistakes I see developers make constantly and how to fix them: 1. Not understanding async/await ⚡ → Wrong: | const data = fetch('https://lnkd.in/dMDBzbsK'); console.log(data); // Promise {pending} | → Right: | const data = await fetch('https://lnkd.in/dMDBzbsK'); | 2. Using var instead of let/const → var is function scoped and causes weird bugs → Always use const by default. let when you need to reassign. Never var. 3. == instead of === → 0 == "0" is true in JavaScript 😱 → Always use === for comparisons. Always. 4. Mutating state directly in React → Wrong: user.name = "Shoaib" → Right: setUser({...user, name: "Shoaib"}) 5. Forgetting to handle errors in async functions → Always wrap await calls in try/catch → Silent failures are the hardest bugs to track down 6. Not cleaning up useEffect in React → Memory leaks are real → Always return a cleanup function when subscribing to events 7. Treating arrays and objects as primitives → [] === [] is false in JavaScript → Reference types don't compare like numbers — learn this early JavaScript rewards the developers who understand its quirks. 💡 Which of these caught YOU off guard when you first learned it? 👇 #JavaScript #WebDevelopment #Frontend #FullStackDeveloper #React #Programming #CodingTips #Developer #Tech #Pakistan #LearnToCode #JS #SoftwareEngineering #100DaysOfCode #PakistaniDeveloper

🚀 Just published my latest blog on Template Literals in JavaScript! Tired of messy string concatenation using +? Learn how template literals make your code cleaner, readable, and modern 💡 ✅ Real-world examples ✅ Before vs After comparisons ✅ Practical use cases Perfect for beginners in web development 👨💻 🔗 Read here: https://lnkd.in/gJ6qP-ch #JavaScript #WebDevelopment #Coding #Frontend #100DaysOfCode

😵💫𝗢𝗻𝗲 𝗼𝗳 𝘁𝗵𝗲 𝗺𝗼𝘀𝘁 𝗰𝗼𝗻𝗳𝘂𝘀𝗶𝗻𝗴 𝘁𝗵𝗶𝗻𝗴𝘀 𝗶𝗻 𝗝𝗮𝘃𝗮𝗦𝗰𝗿𝗶𝗽𝘁: `...` At first glance, it looks simple. But depending on where you use it, it completely changes its role. Same syntax. Different behavior. That’s where most developers get tripped up. So I decided to break it down clearly: ✍️ New Blog Published: 𝗦𝗽𝗿𝗲𝗮𝗱 𝘃𝘀 𝗥𝗲𝘀𝘁 𝗢𝗽𝗲𝗿𝗮𝘁𝗼𝗿𝘀 𝗶𝗻 𝗝𝗮𝘃𝗮𝗦𝗰𝗿𝗶𝗽𝘁: 𝗘𝘅𝗽𝗮𝗻𝗱 𝗼𝗿 𝗖𝗼𝗹𝗹𝗲𝗰𝘁 𝗟𝗶𝗸𝗲 𝗮 𝗣𝗿𝗼 https://lnkd.in/gFPgrdEv 🔍 What you’ll learn: 🔹 When ... acts as a Spread Operator (expanding data) 🔹 When it becomes a Rest Operator (collecting data) 🔹 Real-world use cases to eliminate confusion Hitesh Choudhary Piyush Garg Chai Aur Code Anirudh J. Akash Kadlag Suraj Kumar Jha Nikhil Rathore Jay Kadlag DEV Community #JavaScript #WebDevelopment #TechnicalWriting #LearningInPublic #Chaicode #Cohort

🚀 𝐃𝐚𝐲 6 – 𝐉𝐚𝐯𝐚𝐒𝐜𝐫𝐢𝐩𝐭 𝐄𝐯𝐞𝐧𝐭 𝐋𝐨𝐨𝐩 (𝐒𝐢𝐦𝐩𝐥𝐞 & 𝐂𝐥𝐞𝐚𝐫) JavaScript is single-threaded… 👉 But then how does it handle things like `setTimeout`? 🤔 Let’s understand the real flow 👇 --- 💡 The Setup JavaScript uses: * Call Stack → runs code * Web APIs → handles async tasks * Callback Queue → waits for execution * Event Loop → manages everything --- 💡Example: console.log("Start"); setTimeout(() => {  console.log("Timeout"); }, 0); console.log("End"); --- 💡 Output: Start End Timeout --- 💡 Why? (Step-by-step) * `Start` → runs immediately * `setTimeout` → sent to Web APIs * `End` → runs immediately * Timer completes → callback goes to Queue * Event Loop checks → Stack empty * Callback pushed to Stack → executes --- ⚡ Key Insight 👉 Even with `0ms`, it does NOT run immediately 👉 It waits until the Call Stack is empty --- 💡 Simple Mental Model 👉 “Async code runs after sync code finishes” --- 💡 Why this matters? Because it explains: * execution order * async behavior * common bugs --- 👨💻 Continuing my JavaScript fundamentals series 👉 Next: **Promises (Async Made Better)** 👀 #JavaScript #WebDevelopment #FrontendDevelopment #Coding #SoftwareEngineer #Tech

𝗜 𝘀𝘁𝗮𝗿𝘁𝗲𝗱 𝗹𝗲𝗮𝗿𝗻𝗶𝗻𝗴 𝗝𝗮𝘃𝗮𝗦𝗰𝗿𝗶𝗽𝘁 𝗮𝗿𝗿𝗮𝘆 𝗺𝗲𝘁𝗵𝗼𝗱𝘀… 𝗮𝗻𝗱 𝗴𝗼𝘁 𝗰𝗼𝗻𝗳𝘂𝘀𝗲𝗱 𝗳𝗮𝘀𝘁. Sometimes my data changed unexpectedly, sometimes it didn’t. The reason? I didn’t understand shallow copy vs deep copy. 𝗜𝗻 𝗝𝗮𝘃𝗮𝗦𝗰𝗿𝗶𝗽𝘁, 𝗼𝗯𝗷𝗲𝗰𝘁𝘀 𝗮𝗻𝗱 𝗮𝗿𝗿𝗮𝘆𝘀 𝗮𝗿𝗲 𝘀𝘁𝗼𝗿𝗲𝗱 𝗯𝘆 𝗿𝗲𝗳𝗲𝗿𝗲𝗻𝗰𝗲. 𝗦𝗼 𝘄𝗵𝗲𝗻 𝘆𝗼𝘂 “𝗰𝗼𝗽𝘆” 𝘁𝗵𝗲𝗺, 𝘆𝗼𝘂 𝗺𝗶𝗴𝗵𝘁 𝘀𝘁𝗶𝗹𝗹 𝗯𝗲 𝗽𝗼𝗶𝗻𝘁𝗶𝗻𝗴 𝘁𝗼 𝘁𝗵𝗲 𝘀𝗮𝗺𝗲 𝗱𝗮𝘁𝗮. That’s why methods like slice() and concat() can be tricky—they create shallow copies, not deep ones. If you're learning JS, don’t skip this concept. It makes everything much clearer. I wrote a short blog explaining this with examples—would love your feedback. 𝗟𝗶𝗻𝗸: https://lnkd.in/djWsqePD Senthil Kumar Thangavel DHILEEPAN DHANAPAL MentorBridge #javascript #shallowcopy #deepcopy #arraymethods #es6 #frontend #react #blogging #mentorbridge

🏗️ Constructor Functions (Before Classes) Before class existed in JavaScript, developers used this: function User(name) { this.name = name; } User.prototype.sayHi = function () { console.log(this.name); }; const user1 = new User("Ahmed"); At first, it looks old… but it teaches something powerful. 💡 What’s really happening: user1 = { name: "Ahmed", __proto__: User.prototype } 🔥 Key idea: 👉 Methods are stored in prototype 👉 All instances share them So instead of duplicating functions in memory… ✔ One function ✔ Shared across all objects 🧠 Why this matters: This is the real foundation behind: Classes Inheritance Object behavior in JS 🚀 My takeaway: Constructor functions may look outdated… but they reveal how JavaScript actually works. And once you understand them, classes become much clearer. #JavaScript #OOP #WebDevelopment #Frontend