Muhammad Afzaal Hassan’s Post

Today I practiced generating my checkout page dynamically using JavaScript. Instead of writing all the HTML manually, I used JavaScript to create the elements and display products on the page. It made me realize how powerful the DOM is when building real applications. I also fixed a small but confusing bug with radio buttons. When I selected an option for one product, it affected other products too. I learned that radio buttons are grouped by their "name" attribute — so each product needs its own unique name. What I learned today: JavaScript can build your entire UI dynamically. Small bugs usually teach big lessons. Understanding how things work is more important than just making them work. Slowly but surely improving every day. #Day4OfTakingJavaScriptSeriously The radio selector input is the circle with black dot inside

Parser-blocking JavaScript is often an overlooked issue in frontend performance. When the browser encounters a synchronous <script> tag: • HTML parsing pauses • DOM construction stops • Script executes • Rendering is delayed This issue can easily be missed, but it is measurable in DevTools. I conducted an experiment, recorded the Performance trace, and documented how using defer alters the entire timeline. The difference is immediate and visible. #WebPerformance #JavaScript #FrontendDevelopment #HTML

🚀 Built a small JavaScript project: Guess The Number Game Features: • Random number generation using JavaScript • User input validation • Dynamic feedback (Too high / Too low) • Attempt tracking Tech Stack: HTML • CSS • JavaScript This project helped me practice DOM manipulation and basic game logic. Try it here: https://lnkd.in/gMDTeM8N #webdevelopment #javascript #frontend #learning

Type Coersion in JavaScript. 1. "2" + "2", JavaScript thinks these are two strings that's why result will be 22. Here + is considered as concatenation operator. 2. So now 22 - "2" = 20, When we use -,/,÷ in between two variables JavaScript consider both variables as number that's why result of 22-"2"=20 #javascript #webdevelopment

Understanding event.preventDefault() is fundamental in JavaScript. By default: • Forms submit • Links navigate • Browser triggers built-in actions Using preventDefault(): • Stops the automatic behavior • Lets JavaScript handle the logic • Essential for modern SPAs • Prevents unnecessary page reloads If you're building React or any SPA, this concept is non-negotiable. Master browser behavior before mastering frameworks.

-- Did you know this in JavaScript? typeof null === "object" // true Looks wrong, right? It is. null is not an object. It’s a primitive value that represents the intentional absence of a value. So why does JavaScript say it's an object? Because of a historical bug from the early days of JavaScript. The mistake shipped, the web grew, and now it can’t be fixed without breaking existing websites. That’s why: typeof null // "object" still returns "object" today. Lesson: Don’t use typeof to check for null. Instead, do this: value === null Sometimes, understanding JavaScript means understanding its history — not just its syntax.

Ever wondered how JavaScript remembers variables even after a function has finished execution? It's The magic of Closure.  A closure gives a function access to its outer scope. In JavaScript, closures are created every time a function is created, at function creation time. Example: function outer() {  let count = 0;  return function inner() {   count++;   console.log(count);  }; } const counter = outer(); counter(); Result => 1 counter(); Result => 2 counter(); Result => 3 Explanation: Inner function remembers count from outer. Every time you call counter(), it retains the previous value. Usefulness of Closure: => Data encapsulation (private variables) => Memoization / caching => Event handlers & async callbacks Do you use closures in your projects? Share your use case below! #JavaScript #WebDevelopment #Closures #ReactJS #NexjJS #MERNStack #CodingTips

== VS === It looks equal. But JavaScript decides otherwise. == compares values, but first, it silently converts types. That automatic conversion is called type coercion. A string becomes a number. A boolean becomes 0 or 1. Different types can suddenly become “equal.” Now === is strict. No conversion. No assumptions. It compares value and type exactly as they are. "5" === 5 // false Different types. Different result. This is one of the most common JavaScript quirks — and one of the most dangerous in real-world frontend development. Understanding type coercion is essential for writing clean code, avoiding subtle programming bugs, and mastering JavaScript interview concepts. Follow CodeBreakDev for code that looks right… but isn’t. #JavaScript #WebDevelopment #FrontendDev #JSTips #TypeCoercion #CleanCode #CodingMistakes #JavaScriptTips #SoftwareEngineering

JavaScript be like: NaN = Not a Number typeof NaN = “number” Make it make sense 😄 Fun part? NaN is technically a numeric value in JavaScript — it represents an invalid number result (like 0/0). 🙃 And it gets better: NaN === NaN → false Only JavaScript can be this confident and confusing at the same time. #JavaScript #JS #DeveloperHumor #WebDevelopment

Yesterday poll answer and explanation console.log([2] == [2]); // false 👀 In JavaScript arrays are objects (reference types). So, when both sides are objects (reference types), JavaScript does not compare their values. Instead, it compares their memory references. console.log([2] == 2); // true 🤯 So here, left operand is an object (reference type) and right operand is a (primitive type) is number. In this case, type coercion happens. The reference type is first converted into a primitive. [2].toString() // "2" and it becomes "2" == 2 With ==, JavaScript converts string to number: Number("2") == 2, It becomes 2 == 2 So the final output is, false, true Hope this explanation is helpful to someone 😊 #JavaScript #FrontendDeveloper #WebDevelopment #LearningJavaScript #InterviewPrep