How to parallelize requests in JavaScript with Promise.all()

📌 Day 19 of My JavaScript Brush-up Series Today, I tackled one of the most crucial yet often confusing topics in JavaScript: the Event Loop and Concurrency Model 🌀 If you’ve ever wondered how JavaScript handles multiple tasks at once (even though it’s single-threaded), this is the secret sauce behind it. 👉🏿 JavaScript Is Single-Threaded JavaScript runs on one main thread, meaning it can only execute one task at a time. But thanks to the event loop, it still manages to handle multiple operations efficiently like responding to clicks, fetching data, or running timers all without freezing. 👉🏿 How It Works (Simplified Flow) 1. Call Stack → Where synchronous code runs (line by line). 2. Web APIs → Handle async tasks like fetch(), setTimeout(), or event listeners. 3. Callback Queue / Microtask Queue → Store callbacks and promises waiting to be executed. 4. Event Loop → Keeps checking: “Is the call stack empty? If yes, push the next task from the queue.” This creates the illusion of concurrency while keeping everything non-blocking. 👉🏿 Example 👇🏿 console.log("Start"); setTimeout(() => console.log("Timeout"), 0); Promise.resolve().then(() => console.log("Promise")); console.log("End"); 🧠 Output: Start End Promise Timeout Here’s why: ✍🏿 console.log("Start") and console.log("End") run first (synchronous). ✍🏿 The promise goes into the microtask queue (executed before timeouts). ✍🏿 The timeout callback runs last from the callback queue. 💡 Key Takeaway: ✍🏿 JS runs on a single thread, but stays non-blocking through async APIs and the event loop. ✍🏿 Microtasks (Promises) run before macrotasks (timeouts, intervals). ✍🏿 The event loop keeps everything smooth and responsive. 📸 I’ve attached a visual showing how the call stack, web APIs, queues, and event loop interact 👇🏿 👉🏿 Question: When did the event loop finally “click” for you? #JavaScript #LearningInPublic #WebDevelopment #DaysOfCode #Frontend #AsyncJS

7 Underrated JavaScript Features That Will Save Your Time I was scrolling through a developer subreddit the other day and stumbled upon a goldmine: a thread about the most underrated JavaScript features. It wasn't about the flashy new frameworks, but the quiet, built-in tools that do the heavy lifting without any fanfare. These are the features that make you look at your old code (or that giant utils.js file) and think, "I could have just used that?" So I've compiled the seven best ones. These aren't just clever tricks; they're battle-tested solutions that can genuinely make your code cleaner, faster, and easier to read. But before we dive in, a quick word on setup. To use some of these modern goodies, especially in a Node.js environment, you need to be on a recent version. Juggling different Node versions for different projects can be a real pain. If you've ever found yourself fighting with nvm or brew, you know what I mean. A tool like ServBay can be a lifesaver here, letting you install and switch between Node.js versions with a single cl https://lnkd.in/dg4EH6tn

7 Underrated JavaScript Features That Will Save Your Time I was scrolling through a developer subreddit the other day and stumbled upon a goldmine: a thread about the most underrated JavaScript features. It wasn't about the flashy new frameworks, but the quiet, built-in tools that do the heavy lifting without any fanfare. These are the features that make you look at your old code (or that giant utils.js file) and think, "I could have just used that?" So I've compiled the seven best ones. These aren't just clever tricks; they're battle-tested solutions that can genuinely make your code cleaner, faster, and easier to read. But before we dive in, a quick word on setup. To use some of these modern goodies, especially in a Node.js environment, you need to be on a recent version. Juggling different Node versions for different projects can be a real pain. If you've ever found yourself fighting with nvm or brew, you know what I mean. A tool like ServBay can be a lifesaver here, letting you install and switch between Node.js versions with a single cl https://lnkd.in/dg4EH6tn

Understanding JavaScript Scope and Closures: A Deep Dive into Lexical Environments So you've been writing JavaScript for a while now, and you keep hearing about "closures" and "lexical scope." Maybe you've even used them without realizing it. Let's break down what's really happening under the hood when you create functions in JavaScript. JavaScript is incredibly flexible when it comes to functions. You can create them anywhere, pass them around like hot potatoes, and call them from completely different parts of your code. But this flexibility raises some interesting questions: What happens when a function accesses variables from outside its own scope? If those outer variables change after the function is created, which values does the function see? When you pass a function somewhere else and call it, can it still access those outer variables? Before we dig into the answers, a quick note: I'll be using let and const in my examples. They behave the same way for our purposes here, and they're what you should be using in modern JavaScript anyway. Variables declared with https://lnkd.in/g7Ga_FsG

Understanding JavaScript Scope and Closures: A Deep Dive into Lexical Environments So you've been writing JavaScript for a while now, and you keep hearing about "closures" and "lexical scope." Maybe you've even used them without realizing it. Let's break down what's really happening under the hood when you create functions in JavaScript. JavaScript is incredibly flexible when it comes to functions. You can create them anywhere, pass them around like hot potatoes, and call them from completely different parts of your code. But this flexibility raises some interesting questions: What happens when a function accesses variables from outside its own scope? If those outer variables change after the function is created, which values does the function see? When you pass a function somewhere else and call it, can it still access those outer variables? Before we dig into the answers, a quick note: I'll be using let and const in my examples. They behave the same way for our purposes here, and they're what you should be using in modern JavaScript anyway. Variables declared with https://lnkd.in/g7Ga_FsG

Learn how to add console.log line break in JavaScript using newline characters, template literals & multiple logs. Improve readability in Node.js and browsers.

💡 Do you know the shortest program in JavaScript? Yes — it’s an empty file! Even if there’s literally nothing in your JS file, the JavaScript engine still does important work behind the scenes. Here’s why: 1️⃣ Global Execution Context is Created JS first sets up a Global Execution Context (GEC). This is the space where global variables live, functions are defined, and the global object is connected. 2️⃣ Global Object is Initialized Browser: window → contains console, document, alert, setTimeout… Node.js: global → contains process, Buffer, require, setTimeout… This object is the foundation for all code, even if the file is empty. 3️⃣ this Refers to the Global Object Inside the global context: Browser → this === window Node → this === global Example: console.log(this); // window (browser) or [Object: global] (Node) 4️⃣ No Code = No Execution, But Environment Exists The engine checks for statements to run. If the file is empty, nothing executes — but all the setup has already happened. ✅ Takeaway: The program is syntactically valid (no errors) It’s functionally empty (nothing runs) Global environment is initialized (GEC, global object, this)

👉✅ “Setting a one-week goal to revise JavaScript again.” Day 5th Topic 👇 🚀 Understanding Synchronous vs Asynchronous JavaScript If you’ve ever wondered why some JavaScript code waits for one task to finish while other code seems to “run in the background,” it all comes down to how JavaScript handles synchronous and asynchronous operations. 🧩 Synchronous JavaScript Executes code line by line, in order. Each task must finish before the next one starts. Simple to understand, but can block the main thread — leading to performance issues when handling time-consuming tasks (like network requests or file reading). ⚡ Asynchronous JavaScript Allows tasks to run without blocking other operations. JavaScript uses mechanisms like callbacks, Promises, and async/await to handle these tasks. Perfect for fetching data from APIs, timers, or any operation that takes time to complete. 💡 Example: // Synchronous console.log("Start"); console.log("Processing..."); console.log("End"); // Asynchronous console.log("Start"); setTimeout(() => console.log("Processing..."), 2000); console.log("End"); 🧠 Output: Start End Processing... The asynchronous version lets the program continue running while waiting for the timeout — improving performance and user experience. 📘 In short: Synchronous = Sequential execution. Asynchronous = Non-blocking, efficient execution. #JavaScript #WebDevelopment #AsyncProgramming #Coding #DeveloperCommunity #100DaysOfCode #FrontendDevelopment #LearnToCode #TechTips

Event Loop in JavaScript — How JS Executes Code Step by Step Here’s your LinkedIn-style post 👇 🧠 JavaScript Event Loop — The Brain Behind Asynchronous Magic 🌀 Ever wondered how JavaScript handles multiple tasks at once even though it’s single-threaded? 🤔 The answer lies in the Event Loop, one of the most powerful concepts in JS. 💡 Definition: The Event Loop is the mechanism that allows JavaScript to perform non-blocking, asynchronous operations — by coordinating between the Call Stack, Web APIs, and Task Queues. ⚙️ How It Works: 1️⃣ Call Stack: Where JS executes your code line by line. If a function calls another, it gets stacked on top. 2️⃣ Web APIs: Handles async operations like setTimeout(), fetch(), or event listeners. 3️⃣ Task Queues (Micro & Macro): Stores completed async tasks waiting to be executed. 4️⃣ Event Loop: Continuously checks if the Call Stack is empty. If empty, it moves the next task from the queue into the stack. 🧩 Example: console.log("1️⃣ Start"); setTimeout(() => console.log("3️⃣ Timeout callback"), 0); Promise.resolve().then(() => console.log("2️⃣ Promise resolved")); console.log("4️⃣ End"); ✅ Output: 1️⃣ Start 4️⃣ End 2️⃣ Promise resolved 3️⃣ Timeout callback 👉 Promises (microtasks) run before timeouts (macrotasks) — thanks to the Event Loop’s priority order. ⚙️ Why It’s Important: ✅ Helps debug async behavior ✅ Avoids race conditions ✅ Essential for understanding Promises & Async/Await 🔖 #JavaScript #EventLoop #AsyncProgramming #WebDevelopment #Frontend #JSConcepts #CodingTips #100DaysOfCode #KishoreLearnsJS #WebDevCommunity #DeveloperJourney