JavaScript Interview Questions: Frontend Developer Prep

🚀 Recent Interview Experience – JavaScript Questions If you’re preparing for a Frontend / JavaScript interview, these questions were asked frequently 👇 🟨 Advanced JavaScript Concepts 1️⃣ What is Execution Context? 2️⃣ Difference between Scope & Lexical Scope 3️⃣ What is Temporal Dead Zone (TDZ)? 4️⃣ Explain this keyword in different scenarios 5️⃣ What is Prototype & Prototypal Inheritance? 6️⃣ Difference between null vs undefined 7️⃣ Arrow function vs Normal function 8️⃣ What are Higher Order Functions? 9️⃣ What is Currying in JavaScript? 🔟 What is Memory Leak and how to prevent it? 👉 Follow NURSID ANSARI for upcomming post on: hashtag #JavaScript hashtag #FrontendDeveloper hashtag #WebDevelopment hashtag #InterviewPrep hashtag #ReactJS

🚀 JavaScript Interview Essentials – call(), apply() & bind() Understanding call(), apply(), and bind() is crucial for mastering this keyword in JavaScript and is a frequently asked interview topic for frontend and full-stack roles. 🔹 call() – Invokes the function immediately with arguments passed individually 🔹 apply() – Invokes the function immediately with arguments as an array 🔹 bind() – Returns a new function with a bound this (does not execute immediately) 📌 Knowing when to use each helps write cleaner, reusable, and more predictable code. Saved this as a quick visual reference for interviews and daily development. Hope it helps fellow developers! 🙌 #JavaScript #WebDevelopment #Frontend #FullStack #NodeJS #InterviewPreparation #Learning #SidTech

Day 2/365 – JavaScript Interview Question 🔥 const obj = { name: "JS", getName() { console.log(this.name); } }; const fn = obj.getName; fn(); Output: undefined Why is the output undefined? Because this depends on how a function is called, not where it is written. When a method is assigned to a variable and called independently, it loses its object context, so this no longer refers to the original object. Interview Tip: 👉 Always check the function invocation when working with this. #javascript #frontend #thiskeyword #365daysofcode #jsinterview #interviewprep #webdevelopment

🧠 JavaScript Skills Every Frontend Developer Should Know I regularly revise these JavaScript concepts because they show up in real projects and interviews: • Closures • Promises & async/await • map, filter, reduce • Scope & hoisting • Event handling Strong fundamentals make React easier and cleaner to write. #JavaScript #FrontendDeveloper #ReactJS #InterviewPrep #LearningInPublic

🚀 DAY 40 – JavaScript Interview Prep Asynchronous JavaScript ⭐ --- Microtasks vs Macrotasks 👨💻 Interviewer may ask: 👉 What is the difference between Microtasks and Macrotasks in JavaScript? ✅ Simple Explanation JavaScript handles async operations using the Event Loop, which decides when and in what order tasks are executed. 🔹 Microtasks (Higher Priority) : Executed right after the current call stack Always run before Macrotasks Examples: Promise.then / catch / finally queueMicrotask() MutationObserver 🔹 Macrotasks (Lower Priority) Executed after all Microtasks are completed Examples: setTimeout setInterval DOM events 🧠 One-Line Version (Quick Round) : In JavaScript, asynchronous operations are handled by the Event Loop. After the call stack is empty, the Event Loop first executes all Microtasks, and only then picks the next Macrotask. 💡 That’s why Promise.then() runs before setTimeout() #AsynchronousJavaScript #JavaScript #InterviewPrep #EventLoop #Microtasks #Macrotasks #FrontendInterview #ReactJS

Your JavaScript code might be leaking memory… and you don’t even know it ⚠️ Closures are powerful, but they come with a hidden cost. When a closure captures its scope, the garbage collector can’t free anything in that scope, even variables the closure never touches. One tiny function can accidentally keep huge objects alive forever. That’s how silent memory leaks are born. If you want to write efficient JavaScript and sound confident in front end interviews, this is non-negotiable knowledge. 👉 Level up your memory management, and learn the patterns interviewers love. Check out GFE to master advanced JavaScript concepts that actually matter. https://lnkd.in/gY-cAPfx #JavaScript #FrontendDevelopment #WebDevelopment #ReactJS #greatfrontend

🚀 JavaScript Array Methods – Don’t Get Confused Again! Most JS developers know these methods, but many still misuse them in real projects & interviews 👀 This visual breaks down 3 commonly confusing JavaScript array method pairs 👇 ✅ forEach vs map ✅ find vs findIndex ✅ some vs every 💡 Quick tip 👉 If you expect a new array, use map 👉 If you need a value, use find 👉 If you need a boolean check, use some or every These concepts are must-know for: Frontend Developers React / Node Developers JavaScript Interviews 👇 Engage with this post 🔹 Like if this helped you 🔹 Comment which one confused you earlier 🔹 Share with your JS friends 🔹 Follow me for more JS + React interview tips #JavaScript #WebDevelopment #FrontendDeveloper #ReactJS #NodeJS #Programming #CodingTips #JavaScriptTips #InterviewPreparation #Developers #LearnJavaScript

🧠 JavaScript Interview Question – Test Your Fundamentals What will be the output of the following JavaScript code, and why? function A() {} A.prototype = { foo: function() { return 1; } }; const a = new A(); A.prototype.foo = function( ) { return 2; }; console.log(a.foo( )); 💬 Drop your answers in the comments with explanations.  Bonus points if you explain it like you would in a real interview 😉 #JavaScript #Frontend #WebDevelopment #InterviewQuestions #Learning #Developers

Day 5/365 - JavaScript Interview Question🔥 const obj1 = { value: 10 }; const obj2 = { value: 10 }; console.log(obj1 == obj2); // false console.log(obj1 === obj2); // false Why is the output false for both? In javascript objects are compared by reference, not by value. obj1 and obj2 are stored in different memory locations, so even though they look identical, they are not the same object. So: == → checks reference for objects === → also checks reference (and type) Since both references are different → result is false. 🔥This is one of the most common JavaScript interview traps for frontend developers. #javascript #frontend #coding #jsinterview #interview #365daysofjs #js