Understanding var let and const in JavaScript

🚀 Day 963 of #1000DaysOfCode ✨ Difference Between var, let & const in JavaScript These three look similar… but behave very differently in real-world code. In today’s post, I’ve broken down the differences between `var`, `let`, and `const` in a simple and practical way, so you can understand when and why to use each of them. From scope and hoisting to re-declaration and mutability, these concepts directly impact how your code behaves — and are often the reason behind many unexpected bugs. I’ve also explained common mistakes developers make while using them, so you can avoid those pitfalls in your own projects. If you’re writing modern JavaScript, having clarity on this is absolutely essential. 👇 Which one do you use the most — `var`, `let`, or `const`? #Day963 #learningoftheday #1000daysofcodingchallenge #FrontendDevelopment #WebDevelopment #JavaScript #React #CodingCommunity #JSBasics

📣 𝗡𝗲𝘅𝘁 𝗕𝗹𝗼𝗴 𝗶𝘀 𝗛𝗲𝗿𝗲! ⤵️ Synchronous vs Asynchronous JavaScript ⚡🧠 One of the most important JavaScript concepts for understanding how code executes—explained in a simple and beginner-friendly way. 🔗 𝗥𝗲𝗮𝗱 𝗵𝗲𝗿𝗲: https://lnkd.in/gqmv62WJ 𝗧𝗼𝗽𝗶𝗰𝘀 𝗰𝗼𝘃𝗲𝗿𝗲𝗱 ✍🏻: ⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺ ⇢ What synchronous code means ⇢ What asynchronous behavior means ⇢ Blocking vs non-blocking code ⇢ Why JavaScript needs async behavior ⇢ Understanding setTimeout() execution ⇢ API calls and delayed responses ⇢ Simple execution timeline breakdown ⇢ What happens behind the scenes (task queue idea) ⇢ Common beginner confusion with execution order 💬 If you're learning JavaScript and have ever wondered why End logs before a timer finishes, this blog will help make it click. #ChaiAurCode #JavaScript #AsyncJavaScript #Synchronous #WebDevelopment #100DaysOfCoding

updated solution based on feedback by Yevhen Serbyniuk how "this" works in JavaScript. the confusion: this is not consistent. it changes depending on how your function is called. arrow functions work differently than regular functions. callbacks lose context. it's a mess. why it matters: this is everywhere in JavaScript. event handlers, callbacks, class methods. if you don't understand it, you're debugging ghosts. the real issue: regular functions get this from their caller (dynamic binding). arrow functions capture this lexically from where they're defined (static binding). this fundamental difference breaks code constantly. when it breaks hardest: callbacks inside methods. event listeners in classes. promises with then(). async operations. all the places where context gets lost or wrong. the solution: understand what this should be in your context. use arrow functions if you want parent's this. use regular functions with bind() if you want explicit control. the rule: regular functions = this from caller. arrow functions = this from definition scope. know which you need. #javascript #typescript #webdevelopment #buildinpublic #reactjs

🚀 Why Does null Show as an Object in JavaScript? 🤯 While practicing JavaScript, I came across something interesting: let myVar = null; console.log(typeof myVar); // Output: object At first, it feels confusing… why is null an object? 🤔 💡 Here’s the simple explanation: null is actually a primitive value that represents "no value" or "empty". But when JavaScript was first created, there was a bug in the typeof operator. Due to this bug, typeof null returns "object" instead of "null". ⚠️ This behavior has been kept for backward compatibility, so changing it now would break existing code. 🔍 Key Takeaways: null → means "nothing" (intentional empty value) typeof null → returns "object" (this is a historical bug) Objects (like {}) also return "object" 💻 Example: let myObj = { name: "John" }; console.log(typeof null); // object ❌ (bug) console.log(typeof myObj); // object ✅ (correct) 📌 Conclusion: Even though both return "object", they are completely different in meaning. 👉 JavaScript is powerful, but it has some quirky behaviors—this is one of them! #JavaScript #WebDevelopment #CodingJourney #100DaysOfCode #FrontendDevelopment

📚 Blog Series Update! Between projects and busy work hours, I spent some time this week working on Part 3 of my Rediscovering JavaScript series, and now I’m happy to share a new weekend read: Variables, Scope, and Memory 🚀 In this blog post, I explore some of the most important JavaScript fundamentals: 🔹 Primitive vs reference values 🔹 Scope and scope chain 🔹 Execution context 🔹 Memory management & garbage collection These topics may sound basic, but they explain many of the “why did this happen?” moments developers face while coding. 🔗 Part 3 Rediscovering JavaScript (Part 3): Variables, Scope, and Memory: https://lnkd.in/ek8CySJc 🔗Friend link: https://lnkd.in/e4ddDhSc ✨ For this journey, I’m using Professional JavaScript for Web Developers by Nicholas C. Zakas as my main guide. ☕ Wishing you a wonderful weekend and an enjoyable read with your coffee! #JavaScript #WebDevelopment #Frontend #Programming #SoftwareEngineering #DevTips #Medium

Can you explain the JavaScript event loop? Not because the concept is hard, but because explaining it clearly is what actually matters. Here’s the simplest way to break it down: JavaScript runs in a single thread, using a call stack to execute code. 1. Synchronous code runs first → Functions are pushed to the call stack and executed immediately 2. Async tasks are handled by the browser/environment → e.g. setTimeout, fetch, DOM events 3. Once the call stack is empty → the event loop starts working It processes queues in this order: 👉 Microtasks first (Promises, queueMicrotask) 👉 Then macrotasks (setTimeout, setInterval, I/O) Why? - A and D are synchronous → executed first - Promise (C) → microtask queue → runs next - setTimeout (B) → macrotask → runs last Explaining it step by step is simple — but doing it clearly makes all the difference. #Frontend #JavaScript #WebDevelopment #TechInterviews #SoftwareEngineering

#Day16 Understanding Callback Hell in JavaScript. Today I took on one of the most talked-about challenges in asynchronous JavaScript Callback Hell (also known as the Pyramid of Doom). In my Mentorship for Acceleration backend track, I built a simulated ice cream production process using multiple nested setTimeout callbacks to represent real asynchronous steps in a production line. What is Callback Hell? It occurs when we have multiple asynchronous operations that depend on each other, leading to deeply nested callbacks. While the code works, it becomes extremely difficult to read, debug, and maintain as the number of steps increases. It’s called the Pyramid of Doom because of the visual shape the code creates when you have many nested callbacks. Problems it creates: => Very difficult to read and understand the flow. => Hard to debug (which line belongs to which callback?). => Painful to maintain or add new steps. => Error handling becomes messy. => Code looks ugly and unprofessional. #M4ACELearningChallenge #LearningInPublic #JavaScript #CallbackHell #AsynchronousJavaScript

🚀 Day 955 of #1000DaysOfCode ✨ How JavaScript Event Loop Works Behind the Curtains JavaScript looks simple on the surface — but under the hood, a lot is happening to make async code work smoothly. In today’s post, I’ve explained how the JavaScript Event Loop actually works behind the scenes, so you can understand how tasks are executed, queued, and prioritized. From the call stack to the callback queue and microtask queue, this concept explains why some functions run before others — even when the code looks sequential. Understanding the event loop helps you debug tricky async issues, avoid unexpected behavior, and write more predictable code. If you’re working with promises, async/await, or APIs, this is one of those concepts you must truly understand. 👇 What part of the event loop confuses you the most — call stack, microtasks, or callbacks? #Day955 #learningoftheday #1000daysofcodingchallenge #FrontendDevelopment #WebDevelopment #JavaScript #React #CodingCommunity #AsyncJavaScript

I thought JavaScript runs code line by line. It doesn't. Before executing a single line, the JS engine creates something called an Execution Context. Think of it like a stack of plates. Each function call adds a new plate on top. Last plate added is the first one removed. That's your Call Stack. Inside each execution context, two phases happen: Memory Phase — Variables are stored before code runs. var gets stored as undefined. let and const? They exist but are untouchable. That zone is called the Temporal Dead Zone. Execution Phase — Now the code actually runs. Values get assigned. Functions get called. I spent 4 years writing JavaScript. Never knew this was happening under the hood. Day 2. Still here. #JavaScript #BuildingInPublic #100DaysOfCode

🚀 Day 14/30 of My JavaScript Challenge Solved LeetCode 2715 - Timeout Cancellation ✅ 💡 What I Learned Today: ⏳ How setTimeout() delays function execution ❌ How clearTimeout() cancels a scheduled task 🔁 Returning functions from functions (Higher-Order Functions) 🧠 Managing async behavior in JavaScript 📌 Approach: Created a cancellable function that schedules execution using setTimeout(). Then returned a cancelFn which uses clearTimeout() to stop execution before the delay ends. ✨ Key Insight: JavaScript timers can be controlled dynamically, which is useful in search debouncing, API calls, and UI interactions. #JavaScript #LeetCode #30DaysChallenge #WebDevelopment #AsyncJavaScript #CodingJourney #ProblemSolving