Event Loop Order: Async JS Gotchas in Production

Because events in JavaScript ""bubble"" up the DOM tree, you can attach a single event listener to the parent container and use event.target to figure out which child was clicked. JavaScript // Attach ONE listener to the parent <ul> document.getElementById('item-list').addEventListener('click', (event) => { // Check if the clicked element was a button if (event.target.tagName === 'BUTTON') { const itemId = event.target.dataset.id; console.log(`Item ${itemId} clicked!`); } }); This uses drastically less memory and automatically handles new items added to the list dynamically—no need to attach new listeners when the DOM updates! #JavaScript #WebPerformance #CodingInterviews #FrontendDev #TechTips"

JAVASCRIPT NOTES — PART 5 Some JavaScript bugs aren’t about logic — they’re about understanding how the language behaves internally. This post covers: • Stack vs Heap (how memory is handled) • Shallow vs Deep copy • The real behavior of the `this` keyword • Garbage collection basics • Debouncing & Throttling for UI performance These are the concepts that explain why code behaves the way it does. Once memory and execution flow are clear, JavaScript becomes far more predictable. #JavaScript #WebDevelopment #FrontendDeveloper #InterviewPrep #LearningInPublic #Debouncing #Prototypes #Consistency

JavaScript destructuring trick: Rename while destructuring: const { name: userName, id: userId } = user; No more variable name conflicts. No more confusing abbreviations. Small syntax, big clarity. #JavaScript #CodingTips #CleanCode

In today’s session, we focused on understanding asynchronous behavior in JavaScript and how to manage it effectively. Topics covered: • Promise states – pending, fulfilled, rejected • Proper chaining with .then() • Error handling using .catch() • Promise.resolve() • Promise.allSettled() • async/await with try-catch • Microtasks vs Macrotasks • Understanding the JavaScript Event Loop Step by step, building a stronger foundation in modern JavaScript 💻✨ #JavaScript #AsyncProgramming #WebDevelopment Hitesh Choudhary

🔥 Async/Await vs Promise chaining: they look the same… until you predict the logs 😅 ❓ What’s the output order? A) A B F D C E B) A D B C F E C) A B D F C E D) A B F C D E ❓If we change await Promise.resolve() to await null, does the order change? 💬 Drop your answers + reasoning 👇 #CodeSnatch #javascript #asyncawait #promises #eventloop #interviewprep

🚨 JavaScript Truth Bomb: “Everything is an object”… so why does typeof fn say "function"? Quick reality check: functions are objects in JS. But typeof goes a step further. It checks if that object is callable. If yes, it returns "function" instead of "object". That’s not a bug, it’s intentional: 🔥 Early JS needed a simple way to detect callable values 🔥 So functions got a special typeof result 🔥 They still behave like objects with extra behavior 👉 Functions are objects with a [[Call]] method capability. What weird JavaScript behavior confused you the most? 👇 #JavaScript #Coding #DeveloperLife #WebDev

𝗪𝗲𝗹𝗰𝗼𝗺𝗲 𝘁𝗼 𝗗𝗮𝘆 𝟭𝟲 JavaScript is single-threaded. So how can it handle: • Synchronous code • Promises • Timers All at the same time? The answer is task priority and the Event Loop. In this video, I demonstrate exactly how tasks are added and executed based on priority. 𝙒𝙝𝙚𝙣 𝙘𝙤𝙙𝙚 𝙧𝙪𝙣𝙨: -> Code executes first (Call Stack). -> Promise callbacks go to the Microtask Queue. -> setTimeout callbacks go to the Macrotask Queue. 𝙃𝙤𝙬 𝙩𝙝𝙚 𝙀𝙫𝙚𝙣𝙩 𝙇𝙤𝙤𝙥 𝙋𝙞𝙘𝙠𝙨 𝙏𝙖𝙨𝙠𝙨 When the Call Stack becomes empty: -> Run ALL microtasks (Promises first). -> Then run ONE macrotask (setTimeout). -> Repeat the cycle. Microtasks always have higher priority. 𝙏𝙝𝙞𝙨 𝙥𝙧𝙞𝙤𝙧𝙞𝙩𝙮 𝙨𝙮𝙨𝙩𝙚𝙢 𝙞𝙨 𝙬𝙝𝙖𝙩 𝙖𝙡𝙡𝙤𝙬𝙨 𝙅𝙖𝙫𝙖𝙎𝙘𝙧𝙞𝙥𝙩 𝙩𝙤: • Stay responsive • Execute async logic predictably • Simulate concurrency while staying single-threaded #JavaScript #WebDevelopment #FrontendDevelopment #EventLoop #AsyncJavaScript #SoftwareEngineering #DeveloppementWeb #JavaScriptFR

How JavaScript engines actually handle arrays, and there’s a lot of hidden logic going on. ⚙️ The main thing is the difference between Packed (continuous) and Holey (arrays with empty gaps). Here is what I learned: SMI is the best: Arrays with only small integers are the most optimized. One-way downgrade: If you add a float or string to an integer array, the engine downgrades its optimization. Even if you remove that item later, it doesn't go back to being as fast as it was. Holes are costly: When JS hits an empty gap, it has to check all the way up the prototype chain to find a value. It’s one of the most expensive operations in the engine. A simple tip I learned: Avoid using "new Array(3)" because it creates holes immediately. Starting with [ ] keeps things much more optimized. #LearningInPublic #Javascript #WebDev

Day (58/100) #100DaysOfWEB Building an Authentication System using JavaScript and LocalStorage. Code: https://lnkd.in/egXytznT Live: https://lnkd.in/ey3Pq9Um #100DaysOfCode #JavaScript #WomenInTech #TorontoTech #SenecaCollege #BuildInPublic #100daysofchallenge