Sasikumar Velmurugan’s Post

🚀 Understanding the JavaScript Event Loop (In Simple Terms) Many developers use JavaScript daily, but truly understanding the Event Loop changes how you write asynchronous code. 🔹 JavaScript is single-threaded 🔹 It uses a Call Stack to execute functions 🔹 Asynchronous tasks (setTimeout, Promises, API calls) go to Web APIs 🔹 Callbacks move to the Callback Queue 🔹 Promises go to the Microtask Queue 🔹 The Event Loop constantly checks: “Is the Call Stack empty? If yes, execute tasks from the queue.” 💡 Important Concept: Microtasks (Promises) are executed before Macrotasks (setTimeout). Example: console.log("Start"); setTimeout(() => console.log("Timeout"), 0); Promise.resolve().then(() => console.log("Promise")); console.log("End"); Output: Start End Promise Timeout Because: Microtask queue > Macrotask queue Understanding this helps avoid: Unexpected execution order Performance issues Callback confusion As a Full Stack Developer, mastering fundamentals like Event Loop improves debugging and architecture decisions. #JavaScript #EventLoop #WebDevelopment #Frontend #NodeJS #FullStackDeveloper

⚡ Understanding the JavaScript Event Loop (Simplified) One concept that helped me understand JavaScript much better is the Event Loop. JavaScript is single-threaded, but it can still handle asynchronous operations like API calls, timers, and promises. How? Because of the Event Loop. In simple terms: 1️⃣ JavaScript executes synchronous code first (Call Stack). 2️⃣ Async tasks like setTimeout or API requests go to Web APIs. 3️⃣ Once completed, they move to the Callback Queue. 4️⃣ The Event Loop checks if the call stack is empty and pushes callbacks back for execution. This is why code like this works: console.log("Start"); setTimeout(() => { console.log("Async Task"); }, 0); console.log("End"); Output: Start End Async Task Even with 0 delay, async tasks wait until the call stack is empty. 💬 When did you first learn about the Event Loop? #JavaScript #WebDevelopment #FrontendDevelopment #AsyncProgramming

Most JavaScript developers use async/await every day without actually understanding what runs it. The Event Loop is that thing. I spent two years writing JavaScript before I truly understood how the Event Loop worked. Once I did, bugs that used to take me hours to debug started making complete sense in minutes. Here is what you actually need to know: 1. JavaScript is single-threaded but not blocking The Event Loop is what makes async behavior possible without multiple threads. 2. The Call Stack runs your synchronous code first, always Anything async waits in the queue until the stack is completely empty. 3. Microtasks run before Macrotasks Promise callbacks (.then) execute before setTimeout, even if the timer is zero. This catches a lot of developers off guard. 4. Understanding this helps you write better async code You stop writing setTimeout hacks and start understanding why certain code runs out of order. 5. It explains why heavy computations block the UI A long synchronous task freezes the browser because nothing else can run until the stack clears. The mindset shift: JavaScript is not magic. It follows a very specific execution order and once you see it clearly, you write code that actually behaves the way you expect. 🧠 The Event Loop is one of those concepts that separates developers who guess from developers who know. When did the Event Loop finally click for you? 👇 If this helped, I would love to hear your experience. #JavaScript #WebDevelopment #EventLoop #Frontend #SoftwareEngineering

🧠 Why does some JavaScript run instantly… and some runs later? Because JavaScript can be synchronous and asynchronous. 🔹 Synchronous JavaScript - JavaScript runs one line at a time. - Each task waits for the previous one to finish. Example: console.log("Start"); console.log("Middle"); console.log("End"); Output: Start → Middle → End ✅ Simple ❌ Can block execution 🔹 Asynchronous JavaScript - Some tasks don’t block execution. - They run in the background and return later. Example: console.log("Start"); setTimeout(() => { console.log("Async Task"); }, 2000); console.log("End"); Output: Start → End → Async Task 🔹 Why Async Exists Without async: - APIs would freeze the app - Timers would block everything - UI would become unresponsive 💡 Key Idea JavaScript is single-threaded, but it handles async using Web APIs + Call Stack + Event Loop (We’ll cover this next 👀) 🚀 Takeaway - Sync = step-by-step execution - Async = non-blocking execution Both are essential for real-world apps Next post: Event Loop Explained Simply 🔥 #JavaScript #AsyncJS #Frontend #WebDevelopment #LearnJS #Programming #LearningInPublic

🧠 Ever wondered how JavaScript actually runs your code? Behind the scenes, JavaScript executes everything inside something called an Execution Context. Think of it as the environment where your code runs. 🔹 Types of Execution Context JavaScript mainly has two types: 1️⃣ Global Execution Context (GEC) Created when the JavaScript program starts. It: - Creates the global object - Sets the value of this - Stores global variables and functions - There is only one Global Execution Context. 2️⃣ Function Execution Context (FEC) Every time a function is called, JavaScript creates a new execution context. It handles: - Function parameters - Local variables - Inner functions Each function call gets its own context. 🔹 Two Phases of Execution Every execution context runs in two phases: 1️⃣ Memory Creation Phase JavaScript allocates memory for: - Variables - Functions (This is where hoisting happens) 2️⃣ Code Execution Phase Now JavaScript runs the code line by line and assigns values. 💡 Why This Matters Understanding execution context helps you understand: - Hoisting - Scope - Closures - Call Stack - Async JavaScript It’s one of the most important concepts in JavaScript. More deep JavaScript concepts coming soon 🚀 #JavaScript #ExecutionContext #Frontend #WebDevelopment #LearnJS #Programming #LearningInPublic

New article in my "Building Scalable JavaScript Frameworks" series. Why JavaScript Frameworks Exist And why plain JavaScript eventually stops being enough At some point, every frontend project hits the same wall. What started as simple DOM updates turns into: – shared state everywhere – UI getting out of sync – logic duplicated across components And suddenly things start feeling fragile. Not because JavaScript is bad. But because the scale changed. Frameworks did not appear to make frontend more fashionable. They appeared to solve one core problem: 👉 keeping state and UI in sync reliably This article explores why that problem appears, and why plain JavaScript eventually stops being enough. 👉 Full article in the comments #frontend #javascript #webdevelopment

⚙️ How JavaScript Works Internally JavaScript may look simple, but internally it follows a powerful execution model. 🧠 Core Concepts: 👉 1. Single Threaded 🔹 JavaScript runs on a single thread → one task at a time using a call stack. 👉 2. Execution Context 🔹 Every time code runs, an execution context is created: 🔹 Global Execution Context (GEC) 🔹 Function Execution Context (FEC) 👉 3. Call Stack 🔹 Functions are pushed and popped from the stack (LIFO). 🔹 This is how JS tracks execution. 👉 4. Web APIs (Browser Features) 🔹 Async tasks like setTimeout, DOM events are handled outside the engine. 👉 5. Callback Queue & Event Loop 🔹 Completed async tasks go to the callback queue 🔹 The event loop moves them to the call stack when it’s empty 👉 6. Non-Blocking Behavior 🔹 Because of the event loop, JavaScript handles async operations without blocking execution. 🔁 Flow in Simple Terms: Call Stack → Web APIs → Callback Queue → Event Loop → Call Stack 🚀 Pro Insight: This is why JavaScript can handle async operations like APIs, timers, and user events smoothly. #JavaScript #WebDevelopment #Frontend #InterviewPrep #Developers #Coding #TechBasics

I just spent the entire weekend digging into the JavaScript Event Loop and I'm still reeling from what I learned 🚀 This post is about how the JavaScript Event Loop actually works under the hood, and what that means for our code. I've always known that JavaScript is single-threaded, but it wasn't until I dove deeper that I realized just how much the Event Loop does to make our code seem multi-threaded. The way it handles asynchronous tasks, like timeouts and intervals, is actually pretty genius. It's all about queuing up tasks and executing them one at a time, while still allowing the browser to respond to user input. One of the most interesting things I learned is how the Event Loop interacts with the browser's rendering engine. It's a delicate balance between executing our code and keeping the UI responsive. If our code takes too long to execute, the browser can become unresponsive, which is why it's so important to keep our functions short and sweet. This is especially important when working with large datasets or complex computations. 🔍 The key insight here is that understanding the Event Loop is crucial to writing efficient and responsive code. So, how do you handle complex computations in your code, and what strategies do you use to keep your functions short and sweet? #javascript #eventloop #webdevelopment

JavaScript Event Loop – The Heart of Asynchronous JavaScript JavaScript is single-threaded, yet it can handle multiple operations like API calls, timers, and user interactions efficiently. This is possible because of the Event Loop. 🔹 What is the Event Loop? The Event Loop is a mechanism that allows JavaScript to handle asynchronous operations without blocking the main thread. 🔹 Main Components ✔ Call Stack – Executes synchronous code ✔ Web APIs – Handles async tasks like setTimeout, fetch, DOM events ✔ Callback Queue – Stores completed async tasks ✔ Event Loop – Moves tasks from queue to call stack when it becomes empty 🔹 Example When an API request is made: JavaScript ⬇ Web API handles request ⬇ Response goes to Callback Queue ⬇ Event Loop sends it to Call Stack 🔹 Why Event Loop is Important • Enables asynchronous programming • Prevents UI blocking • Improves application performance • Handles multiple tasks efficiently 💡 Understanding the Event Loop helps developers write better async code using Promises, async/await, and RxJS. #JavaScript #EventLoop #AsyncProgramming #WebDevelopment #FrontendDeveloper

🚀 Day 5/30 – Tip Calculator Continuing my 30 Days JavaScript Projects Challenge. Today I built a Tip Calculator using HTML, CSS, and JavaScript. This project calculates the tip amount, total bill, and how much each person needs to pay when splitting the bill. 💡 Features: • Calculate tip instantly • Split bill among multiple people • Simple and clean UI 🛠 Tech Stack HTML | CSS | JavaScript 🌐 Live Demo https://lnkd.in/gFUy8h3t 💻 GitHub Repository https://lnkd.in/gZRUXmyr Through this project I practiced DOM manipulation, user input handling, and JavaScript calculations. 25 more projects to go 🚀 #javascript #webdevelopment #codingjourney #30daysofcode #mernstack #github