How JavaScript works under the hood: MDN guide on event loop and async programming

JavaScript is not an "interpreted" programming language. JavaScript, called "interpreted," is not its characteristic, but its implementation. The root of JS being interpreted lies mainly in how JS was used. There are multiple devices with: 1. Different machines and CPU architecture 2. tens of browsers with unique JS engines. Here, the best approach is likely to deliver the source code and let browsers handle all the work. So, the engine interpreters have built-in CPU instructions to execute bytecode. But the modern engine, such as Chrome V8, can execute bytecode and compile hot functions to execute directly as machine code. The JS engines compile the bytecode of the hot functions, which means the most often used code gets compiled to machine code and gets compiled and executed under JIT. So, the JS relies upon the browser engines. #javascript #cpu #chrome #browser

💻 JavaScript Code Challenges: Level Up Your Skills 💻 Want to truly master JavaScript? Stop memorizing and start practicing with real engine-level challenges: 1️⃣ Scope & Lexical Environment let a = 10; function test() { let a = 20; console.log(a); } test(); // ? console.log(a); // ? 2️⃣ Closures function counter() { let count = 0; return function() { count++; return count; } } const inc = counter(); console.log(inc()); // ? console.log(inc()); // ? 3️⃣ Hoisting & TDZ console.log(x); // ? let x = 5; console.log(y); // ? var y = 10; ✅ Challenge yourself: Predict the output before running the code. Understand why it behaves that way. That’s how you think like the JS engine! #JavaScript #CodingChallenge #Closures #Scope #Hoisting #LexicalScoping #TDZ #DevCommunity #WebDevelopment #ProgrammingTips #CleanCode

Coming from a C++ background, I was used to working with a true multithreaded language, whre multiple functions could wrestle for CPU time. Then I hit JavaScript… and realized it’s single-threaded. Only one function can actually run at a time. which changed how i approach problems. I was working on a small project — basically just making a div move randomly across the screen. Sounds simple, right? But when you give it independent X and Y targets, things get chaotic fast. The movement looks alive, unpredictable, like it’s thinking. That’s when I learned about requestAnimationFrame(). At first, I thought it just “runs things continuously.” Nope. It schedules them — about 60 times a second. You’re not looping; you’re politely asking the browser to let your code run again at the next frame and if you don’t structure it right, like putting requestAnimationFrame() inside your function but not calling it again outside, your function just fires once and quits. Feels small, but understanding this changed how I think about JavaScript, not as a slower , but as a completely different beast that plays by its own rules. #javascript #frontend

Ever felt lost in the complexities of the Node.js EVENT LOOP? 🤔 Let's demystify this core concept for better JavaScript performance! The Node.js Event Loop (powered by V8 and libUV) is the HEARTBEAT ❤️ of asynchronous JavaScript. Understanding it is CRUCIAL for writing efficient Node.js applications. Here are three key takeaways: 💡 Grasp the difference between BLOCKING and NON-BLOCKING I/O. Blocking I/O halts the entire process, non-blocking doesn't. ⏱️ Understand the nuances of `setImmediate` vs. `setTimeout(0)`. While seemingly similar, they behave differently in the event loop's execution order. `setImmediate` prioritizes I/O cycle, while `setTimeout(0)` goes to the timer queue. 🧵 Optimize your UV_THREADPOOL_SIZE. This determines the number of threads available for asynchronous operations. Increasing it can boost performance for CPU-intensive tasks. What's YOUR favorite Node.js performance tip? Share in the comments! 👇 #Nodejs #JavaScript #EventLoop #Asynchronous #Programming #Backend #Performance

🧱Objects — The Foundation of Everything in JavaScript 🗓️ This week, I focused on JavaScript Objects — and honestly, it changed how I see the language. From arrays to functions, almost everything in JS is built on objects. 💡Learning about prototypes, object methods, and inheritance made me realize how JavaScript manages structure without strict classes. “In JavaScript, objects don’t just hold data — they define behavior.” Once you get comfortable with the prototype chain, JS starts to feel less confusing and more elegant. #JavaScript #OOP #Programming #WebDevelopment #Frontend #CodingJourney #Developers

𝐀𝐥𝐥 𝐚𝐛𝐨𝐮𝐭 𝐡𝐨𝐰 𝐄𝐯𝐞𝐧𝐭 𝐋𝐨𝐨𝐩 𝐰𝐨𝐫𝐤𝐬 𝐢𝐧𝐭𝐞𝐫𝐧𝐚𝐥𝐥𝐲 𝐈𝐧 𝐉𝐚𝐯𝐚𝐒𝐜𝐫𝐢𝐩𝐭 !! Understanding how JavaScript’s event loop works, especially with async/await, is a game changer for any developer. JavaScript doesn’t just run code line by line when async functions are involved. Instead, it uses something called the event loop, which manages different queues to decide what runs when. There are Microtasks (like promises and await) and Macrotasks (like setTimeout), and Microtasks always get priority. This means even when you use await, JavaScript pauses only inside that function but continues running other code outside it. That’s why sometimes console logs appear in unexpected orders! Grasping this helps you write better asynchronous code, avoid tricky bugs, and build smoother apps. Keep digging into these concepts — it’s worth it! In this post, I’m sharing everything you need to know about JavaScript’s event loop — explained in simple words. To make it even easier, I’ve created a set of slides that break down the concept step-by-step. Follow Gourav Roy for more such amazing content !! 𝐂𝐨𝐧𝐧𝐞𝐜𝐭 𝐨𝐧 𝐓𝐨𝐩𝐦𝐚𝐭𝐞 - https://lnkd.in/gyGxA7ut 𝐂𝐨𝐧𝐧𝐞𝐜𝐭 𝐨𝐧 𝐈𝐧𝐬𝐭𝐚𝐠𝐫𝐚𝐦 - https://lnkd.in/djMF2k3Q #JavaScript #EventLoop #AsyncAwait #WebDevelopment #CodingTips #Java

Understanding Async JavaScript JavaScript is single-threaded, meaning it executes code line by line. Slow operations like fetching data from a backend can freeze your app while the code waits. Asynchronous programming solves this by allowing your code to keep running while waiting for tasks like API calls or file reads. Main async patterns in JavaScript: 1.Callbacks 2.Promises 3.Async / Await In the next post, I’ll explain callbacks with an example and their drawbacks.

Control structures and functions are fundamental conceots in javascript, enabling developers to write dynamic and efficient code. Control structures allow you to dictate the flow of your program's execution based on (CONDITIONS).#ALX_SE ,#ALX_FE,#ALX_FE ,#ALX_PDFE,

🔒 JavaScript Closures: The Private Diary Analogy Ever wondered how JavaScript "remembers" things? Let me explain closures with a real-world analogy. Think of a closure like a private diary with a lock: 📖 The diary (outer function) contains your secrets (variables) 🔐 Only you have the key (inner function) to access those secrets ✨ Even after you close the diary, the key still works Why does this matter? The count variable is trapped inside the closure. No one can directly access or modify it from outside. It's like data privacy built into JavaScript! Real-world use case : This powers every search bar you've used that waits for you to stop typing! The key insight: Closures let inner functions remember their environment, even after the outer function has finished executing. Have you used closures in your code today? Share your favorite use case below! 👇 #JavaScript #WebDevelopment #ReactJS #Programming #Frontend #CodingTips #SoftwareEngineering