Node.js Event Loop Issues: Zombie Promises and Error Handling

Most TypeScript bugs I see in production start with one word: "any". Avoid using < any > to "move faster". It almost always slows you down later. If you don’t know the type yet, use < unknown >. Why? Because < unknown > forces you to prove what the value is before you use it. < any > just lets bugs walk straight into production. Rule of thumb: – < any > = silence the compiler – < unknown > = work with the compiler The moment I switched to < unknown > by default, my error handling became clearer and my runtime bugs dropped noticeably. Do you still reach for < any > - or did you make the switch? #TypeScript #JavaScript #Frontend #WebDevelopment

🚀 Mastering the Event Loop in Node.js The Backbone of Async JavaScript Ever wondered how Node.js handles thousands of requests while running on a single thread? The secret lies in the Event Loop. The Event Loop: • Manages non-blocking I/O operations • Prioritizes tasks using microtask and macrotask queues • Delivers high performance without traditional multi-threading • Helps Node.js scale efficiently and reliably #NodeJS #JavaScript #EventLoop #AsyncProgramming #MERNStack #WebDevelopment #BackendDeveloper #Coding #InterviewPreparation #TechLearning #SoftwareEngineering

🚀 The Event Loop Duel: Browser vs. Node.js JavaScript runs on a single thread, but its heartbeat—the Event Loop—changes depending on where it lives. Are you building for 60FPS UI responsiveness or high-throughput servers? Understanding the difference is a career superpower that most developers overlook. Mastering the loop is the thin line between code that "just works" and industrial-grade systems that scale. Dive into the technical breakdown below! 👇 💬 Let’s talk tech: What’s the most "head-scratching" Event Loop bug you’ve ever debugged? Let’s discuss below! #JavaScript #NodeJS #SoftwareEngineering #Performance #Libuv #EventLoop #Coding

#JS_Core (3 of 7) How can #Single_Threaded_Language handle 5 API calls "simultaneously" ?? The truth is, it doesn't. Our single threaded language JavaScript is not a worker but a coordinator Here is what happens under the hood when you trigger an async task - > JS hands off tasks (Timers, Network calls, File I/O) to the environment (Browser APIs or Libuv in Node.js). > It keeps executing your synchronous code immediately. The main thread is never blocked by the "waiting." > Once the environment finishes the task, the Event Loop pushes the result back into the execution queue to be processed. To orchestrate this chaos, we have modern Promise methods as: > .all : Waits for all to succeed. If one fails, the whole operation rejects. > .allSettled : It Waits for everything to finish, regardless of success or failure. > .any : It returns the first promise that succeeds (unless they all fail). > .race : It returns the result of the very first promise to settle #JavaScript #NodeJS #EventLoop #AsyncAwait #SoftwareEngineering #WebDev

🚨 𝐇𝐨𝐰 𝐭𝐨 𝐅𝐢𝐱 𝐓𝐲𝐩𝐞𝐒𝐜𝐫𝐢𝐩𝐭 𝐢𝐬𝐨𝐥𝐚𝐭𝐞𝐝𝐌𝐨𝐝𝐮𝐥𝐞𝐬 𝐄𝐫𝐫𝐨𝐫 𝐢𝐧 𝐍𝐞𝐱𝐭.𝐣𝐬? If your Next.js build fails with this message: Re-exporting a type when isolatedModules is enabled requires using export type Don’t worry, it’s not a complex bug. It’s just about being clear with TypeScript. 𝐖𝐡𝐚𝐭’𝐬 𝐀𝐜𝐭𝐮𝐚𝐥𝐥𝐲 𝐇𝐚𝐩𝐩𝐞𝐧𝐢𝐧𝐠? When `isolatedModules` is enabled, each file is compiled independently. So TypeScript must know exactly: - what is real JavaScript code that needed at runtime. - what is only for type checking. If you export a type like a normal value, the compiler expects it to exist in JavaScript but it doesn’t. That’s why the build fails. ❌ 𝐖𝐫𝐨𝐧𝐠 𝐖𝐚𝐲 export { Profile, saveProfile } from './helpers'; If `Profile` is a type and `saveProfile` is a function, this causes errors in isolated builds. ✅ 𝐂𝐨𝐫𝐫𝐞𝐜𝐭 𝐖𝐚𝐲 // runtime exports export { saveProfile } from './helpers'; // type-only exports export type { Profile } from './helpers'; Easy Rule to Remember: - Use `export {}` for functions, components, constants - Use `export type {}` for types and interfaces Have you encountered this issue? 😀 #creowis #TypeScript #NextJS #FrontendDev #EngineeringTips #WebDevelopment

Full Article & Code Samples: https://lnkd.in/gYBchTs8 Stop awaiting your performance away. 🛑 Are you still running independent API calls sequentially? const user = await fetchUser(); (1s) const posts = await fetchPosts(); (1s) Total: 2 seconds. By mastering Promise.all() and Promise.allSettled(), you can drop that time to 1 second. My latest blog breaks down the Async Essentials: ✅ The 3 Eras: Callbacks ➡️ Promises ➡️ Async/Await. ✅ Resilience: How to handle timeouts with Promise.race(). ✅ The for...of Trap: Why forEach fails with async code. ✅ Best Practices: My checklist for shipping reliable async logic. Level up your JavaScript internals today. #NodeJS #CodingTips #FullStack #JavaScript #CleanCode

Still Using JavaScript in React? Here's What You're Missing I used to think TypeScript was just "extra work"-until I spent 3 hours debugging a runtime error that would've been caught in 3 seconds with static typing. This slide perfectly captures the shift: ❌ Without TypeScript: • Mystery bugs appearing in production • Refactoring feels like defusing a bomb • "What type is this prop again?" *checks 5 files* ✅ With TypeScript: • Errors caught before you hit save • Confidence to refactor entire codebases • IntelliSense that actually reads your mind The messy scribble vs. clean structure isn't just aesthetic—it's the mental load difference between guessing and *knowing*. Sure, there's a learning curve. But the time you "lose" writing types? You 10x it back in debugging hours saved and team onboarding speed. The best part? You don't need to migrate everything. Start with strict mode on new files, let the compiler teach you. React devs-what's your take? TS all the way, or still team JS? #TypeScript #ReactJS #JavaScript #WebDevelopment #FrontendDevelopment #SoftwareEngineering #CleanCode #DeveloperExperience #CodeQuality #TechLeadership #ProgrammingTips #LearnToCode #FullStackDevelopment #ModernWebDev #DevCommunity

Day 5 – Node.js Understanding Promises Today’s topic: Promises in Node.js. Promises are used to handle asynchronous operations in a structured way and avoid callback nesting. A Promise has three states: • Pending • Fulfilled (Resolved) • Rejected .then() is used for success handling. .catch() is used for error handling. Promises make asynchronous code more readable and maintainable compared to callbacks. Next: async/await – a cleaner way to write asynchronous code. #NodeJS #BackendDevelopment #JavaScript #AsyncProgramming #SoftwareEngineering

A small React realization that reminded me why fundamentals matter 👇 Today I ran into a bug that looked like a TypeScript issue at first: orders.map is not a function I was passing an array to a React component, but inside the component it was suddenly… an object. At first glance, it felt like: 👉 “TypeScript is being annoying again.” But the reality was simpler. React components always receive props as an object — in JavaScript and TypeScript alike. TypeScript didn’t cause the bug; it just caught a flawed mental model earlier. A good reminder that many “TS problems” are really React fundamentals resurfacing. Learning isn’t always about new tools — sometimes it’s about refining how we think. #React #TypeScript #Frontend #LearningInPublic #SoftwareEngineering