JavaScript Async: Call Stack & Event Loop Explained

Developers are moving back to vanilla JavaScript for simplicity, performance, and fewer dependencies. 🤓🚀 A short, clear read on what’s motivating this shift in web development. #JavaScript #WebDev

Developers are moving back to vanilla JavaScript for simplicity, performance, and fewer dependencies. 🤓🚀 A short, clear read on what’s motivating this shift in web development. #JavaScript #WebDev

⚡ JavaScript Concept: Event Loop — How JS Handles Async Code JavaScript is single-threaded… yet it handles thousands of async operations smoothly. How? 🤔 👉 The answer is the Event Loop 🔹 Execution Order 1️⃣ Call Stack — runs synchronous code 2️⃣ Web APIs — handles async tasks (setTimeout, fetch, etc.) 3️⃣ Callback Queue — stores completed async callbacks 4️⃣ Event Loop — moves callbacks to the stack 🔹 Example console.log("Start"); setTimeout(() => { console.log("Async Task"); }, 0); console.log("End"); 📌 Output: Start End Async Task 💡 Even with 0ms delay, async code runs after synchronous code. Mastering the Event Loop = mastering async JavaScript 🚀 #JavaScript #EventLoop #AsyncJS #Frontend #WebDevelopment

JavaScript Runtime Environment explained simply JavaScript is single-threaded, but still handles async operations smoothly. How? 👇 ✅ Call Stack – executes synchronous code ✅ Web APIs – handles async work ✅ Microtask Queue – promises & async/await ✅ Callback Queue – setTimeout, events ✅ Event Loop – decides what runs next Important rule: Microtasks always execute before callback queue. Understanding this helped me write better: • async/await logic • API handling • React performance code If you understand the runtime, you understand JavaScript deeply. #JavaScript #WebDevelopment #MERN #ReactJS #FrontendDeveloper #Learning

🚀 JavaScript Insights 🧠 JavaScript is single-threaded, but it can still handle asynchronous operations using the Event Loop. 🌀 The JavaScript Event Loop 🧵 JavaScript runs on a single thread → It executes one task at a time 📞 Call Stack → Executes synchronous code → Runs top to bottom 🗂️ Web APIs → Handles async operations (setTimeout, DOM events, fetch) 📥 Task Queues 🔹 Microtask Queue → Promises (.then, catch, finally) 🔹 Macrotask Queue → setTimeout, setInterval, events 🔁 Event Loop Rule ➡️ When Call Stack is empty: 1️⃣ Execute all Microtasks 2️⃣ Then execute one Macrotask 💡 Key Takeaways ✔ Promises run before setTimeout(0) ✔ 0ms timeout ≠ immediate execution ✔ Microtasks have higher priority 🤔 Did you already know Microtasks run before Macrotasks? #JavaScript #EventLoop #AsyncJS #WebDevelopment #DevTips

⚛️ React: Class Components vs Functional Components with Hooks Class Components • 🧱 Use class syntax • 🔄 State & side effects via lifecycle methods • 🧩 Logic scattered, verbose code • ⚠️ Harder to reuse and test Functional Components with Hooks • 🧠 Use functions • 🪝 State & effects via Hooks (useState, useEffect, useContext) • ♻️ Logic reusable and composable • ✨ Cleaner, maintainable, scalable. Hooks simplify React development, centralize logic, improve reuse, and reduce boilerplate—making functional components the modern standard. #ReactJS #WebDevelopment #FrontendDevelopment #JavaScript #ReactHooks #FunctionalComponents #SoftwareEngineering #CleanCode #WebDev #CodeQuality

🤔 Quick question: If JavaScript is single-threaded, why does it feel asynchronous? When I first learned that JS runs on a single thread, this confused me a lot. How can one thread handle timers, promises, and user events? Turns out… JavaScript isn’t doing this alone 👇 console.log("Start"); setTimeout(() => { console.log("Timeout"); }, 0); console.log("End"); Output: Start End Timeout 💡 What’s really happening? - JavaScript executes synchronous code first - setTimeout is offloaded to Web APIs - Once the call stack is empty, the callback is pushed back for execution - This makes JavaScript feel asynchronous, even though it’s single-threaded Takeaway - JavaScript itself is single-threaded. - Asynchronous behavior comes from the runtime environment (browser / Node.js) and the event loop, not from JS running multiple threads. #JavaScript #WebDevelopment #FullStack #LearningInPublic

When working with arrays in JavaScript, these four methods come up all the time forEach, map, filter, and find. They look similar, but each has a very specific purpose 1. forEach() Used when you want to loop through an array and perform an action (like logging, updating UI). it does not return a new array. 2. map() Used when you want to transform data. Returns a new array with modified values. Perfect for formatting API data. 3. filter() Used when you want to select specific items based on a condition. Returns a new array with matched elements only. 4. find() Used when you want to get a single item that matches a condition. Returns the first matched element, not an array. #JavaScript #ES6 #WebDevelopment #FrontendDeveloper #ReactJS #LearningInPublic

The page is empty? It's probably JavaScript. Modern sites load data via AJAX after the HTML loads. `requests.get()` won't work here. Solutions: 1. Reverse engineer the internal API (Best). 2. Use a rendered browser like Playwright (Easiest). Don't give up just because the source code looks empty. What's the hardest site you've tried to scrape? #javascript #react #webdev #scraping

Customization without compromise. While it’s primarily low-code, you still have the flexibility to inject custom JavaScript/TypeScript for highly specific, pro-code requirements. #HybridDevelopment #ProCode #Extensibility