JavaScript null vs undefined: Understanding the difference

🚀 JavaScript Interview Trap: Arrow Function vs Normal Function (arguments) Most developers think they know this… but get caught in interviews 👇 ❓Question function normal() { console.log(arguments); } const arrow = () => { console.log(arguments); }; normal(1, 2, 3); arrow(1, 2, 3); Output : normal(1,2,3) → [1, 2, 3] arrow(1,2,3) → ReferenceError ! 🤔Why? 👉 Normal functions have their own arguments object 👉 Arrow functions do NOT have arguments Instead, arrow functions inherit arguments from their outer (lexical) scope ⚠️ Interview Twist function outer() { const arrow = () => { console.log(arguments); }; arrow(); } outer(1, 2, 3); ✔️ Output → [1, 2, 3] 💡 Here, the arrow function borrows arguments from outer() Best Practice : Use rest parameters instead of arguments: const arrow = (...args) => { console.log(args); }; arrow(1, 2, 3);// [1, 2, 3] Final Takeaway : 👉 “Arrow functions don’t have their own arguments; they inherit it from the lexical scope.” Drop your comments below 👇 #JavaScript #WebDevelopment #Frontend #CodingInterview #JS #Developers #Programming

JavaScript interview questions I see being asked again and again Although these are basics, they are often overlooked while preparing for more complex topics. These are some of the most commonly asked JavaScript questions across interviews, especially when the focus is on fundamentals and real-world understanding. 1. What is the event loop in JavaScript? 2. What is the difference between "var", "let", and "const"? 3. What is closure and how is it used? 4. What is hoisting in JavaScript? 5. What is the difference between "==" and "==="? 6. What are promises and how do they work? 7. What is the difference between synchronous and asynchronous code? 8. What is "this" in JavaScript and how does it behave? 9. What is the difference between "map", "filter", and "reduce"? 10. What is prototypal inheritance? 11. What are higher-order functions? 12. What is debouncing and throttling? 13. What is the difference between "null" and "undefined"? 14. What is the difference between "call", "apply", and "bind"? 15. What is a polyfill? Can you write a polyfill for "bind"? 16. What is the difference between shallow copy and deep copy? 17. What is event delegation? 18. How does "setTimeout" work under the hood? 19. What is the difference between "setTimeout" and "setImmediate"? 20. What are microtasks and macrotasks? 21. What is currying in JavaScript? 22. What is memoization? 23. What is the difference between "Object.freeze" and "Object.seal"? 24. How does garbage collection work in JavaScript? Strong fundamentals in JavaScript often make a noticeable difference in how you approach real-world problems. Which of these do you find most interesting or tricky? #javaScript #webdevelopment #programming #softwareengineering #InterviewPrep #interview

JavaScript interview questions I see being asked again and again Although these are basics, they are often overlooked while preparing for more complex topics. These are some of the most commonly asked JavaScript questions across interviews, especially when the focus is on fundamentals and real-world understanding. 1. What is the event loop in JavaScript? 2. What is the difference between "var", "let", and "const"? 3. What is closure and how is it used? 4. What is hoisting in JavaScript? 5. What is the difference between "==" and "==="? 6. What are promises and how do they work? 7. What is the difference between synchronous and asynchronous code? 8. What is "this" in JavaScript and how does it behave? 9. What is the difference between "map", "filter", and "reduce"? 10. What is prototypal inheritance? 11. What are higher-order functions? 12. What is debouncing and throttling? 13. What is the difference between "null" and "undefined"? 14. What is the difference between "call", "apply", and "bind"? 15. What is a polyfill? Can you write a polyfill for "bind"? 16. What is the difference between shallow copy and deep copy? 17. What is event delegation? 18. How does "setTimeout" work under the hood? 19. What is the difference between "setTimeout" and "setImmediate"? 20. What are microtasks and macrotasks? 21. What is currying in JavaScript? 22. What is memoization? 23. What is the difference between "Object.freeze" and "Object.seal"? 24. How does garbage collection work in JavaScript? Strong fundamentals in JavaScript often make a noticeable difference in how you approach real-world problems. Which of these do you find most interesting or tricky? #javaScript #webdevelopment #programming #softwareengineering #InterviewPrep #interview

🚀 Out-of-the-Box JavaScript Interview Series – Think Beyond Basics! Tired of the same old JS interview questions like closures, promises, and hoisting? Let’s push the boundaries a bit and explore questions that actually test how you think 💡 Here are a few unconventional JavaScript interview challenges 👇 🔹 1. Why does this work? [] + [] === "" 👉 What’s happening behind the scenes with type coercion? 🔹 2. Can you break this comparison? true == '1' false == '0' 👉 Why does JS behave this way, and how would you avoid pitfalls in real apps? 🔹 3. Predict the output const obj = { a: 1, valueOf() { return 2; } }; console.log(obj + 1); 👉 Which method gets priority: valueOf or toString? 🔹 4. Infinite loop… or not? for (var i = 0; i < 3; i++) { setTimeout(() => console.log(i), 0); } 👉 Why does this print 3 3 3? How would you fix it? 🔹 5. Can you make this true? a == 1 && a == 2 && a == 3 👉 Yes, it’s possible 😏 — but should you ever do it? 💬 These questions are not about memorization. They test: ✔️ Deep understanding of JavaScript internals ✔️ Edge-case thinking ✔️ Real-world debugging mindset 🔥 If you're preparing for senior/frontend roles, this is the level that makes you stand out. Follow for more in this Out-of-the-Box Interview Series 💯 #javascript #frontenddeveloper #webdevelopment #interviewquestions #codinginterview #js #softwareengineering #programming #developers #techinterview

🚀 𝗖𝗹𝗼𝘀𝘂𝗿𝗲𝘀 𝗶𝗻 𝗝𝗮𝘃𝗮𝗦𝗰𝗿𝗶𝗽𝘁 — 𝗢𝗻𝗲 𝗼𝗳 𝘁𝗵𝗲 𝗠𝗼𝘀𝘁 𝗔𝘀𝗸𝗲𝗱 𝗜𝗻𝘁𝗲𝗿𝘃𝗶𝗲𝘄 𝗤𝘂𝗲𝘀𝘁𝗶𝗼𝗻𝘀! If you’ve ever prepared for a JavaScript interview, you’ve definitely come across closures. But do you truly understand them? In simple terms: A closure is when a function “remembers” the variables from its outer scope even after that outer function has finished executing. 𝗪𝗵𝘆 𝗶𝗻𝘁𝗲𝗿𝘃𝗶𝗲𝘄𝗲𝗿𝘀 𝗹𝗼𝘃𝗲 𝘁𝗵𝗶𝘀 𝗾𝘂𝗲𝘀𝘁𝗶𝗼𝗻? Because it tests your understanding of:  • Scope  • Lexical environment  • Memory behavior in JavaScript Quick Example: function outer() {  let count = 0;  return function inner() {   count++;   console.log(count);  }; } const counter = outer(); counter(); // 1 counter(); // 2 Here, inner() still has access to count even after outer() is executed — that’s a closure! Checkout the full video here: 👉https://lnkd.in/gBkyP54r Follow Alpna P. for more related content! 🤔 Having Doubts in technical journey? 🚀 Book 1:1 session with me : https://lnkd.in/gQfXYuQm 🚀IG: https://lnkd.in/gTQhjM_5 🚀 Get Complete React JS Interview Q&A Here: https://lnkd.in/d5Y2ku23 🚀 Get Complete JavaScript Interview Q&A Here: https://lnkd.in/d8umA-53 #JavaScript #Closures #WebDevelopment #Frontend #CodingInterview #LearnToCode #Developers #CodeWithAlpana Gaurav Patel

🚫 Still confused about Lexical Scope vs Other Scopes in JavaScript? This is one of the most asked concepts in frontend interviews — and many developers still get it wrong. Let’s simplify 👇 👉 Lexical Scope (Static Scope) Functions remember where they were defined, not where they are called. That’s why inner functions can access variables from their outer functions. 👉 Types of Scope you MUST know: ✔️ Global Scope – accessible everywhere ✔️ Function (Local) Scope – inside functions only ✔️ Block Scope – inside {} (let & const) 💡 Interview Tip: If you understand how scope works with closures, you’ll crack many tricky JavaScript questions easily. 📌 In the example above: The inner function accesses outerVar because of lexical scope, not because it’s called there. 🔥 Master this → Level up your JavaScript fundamentals. 💬 Comment “SCOPE” if you want more such interview-ready posts 🔁 Share with someone preparing for frontend interviews #javascript #frontenddeveloper #webdevelopment #codinginterview #jsconcepts #100daysofcode #reactjs #developers #programming #interviewprep #techlearning #learnjavascript #scope #closures

🔥 Top 10 JavaScript Interview Questions You Must Know 🔥 (These decide your JS fundamentals) 1️⃣ var vs let vs const var → function scoped let / const → block scoped 👉 const is preferred by default. 2️⃣ What is Hoisting? Variables and functions are moved to the top during execution. 👉 let and const are hoisted but not initialized. 3️⃣ What is Closure? A function remembers variables from its outer scope. 👉 Very common and very important. 4️⃣ == vs === == → compares value (type conversion) === → compares value + type 👉 Always prefer ===. 5️⃣ What is the Event Loop? It handles async operations like callbacks and promises. 👉 Explains how JS is non-blocking. 6️⃣ Promise vs Callback Promise → cleaner, chainable, better error handling Callback → can cause callback hell 👉 Promises improved async code. 7️⃣ What is this keyword? this depends on how a function is called. 👉 Context matters, not where it’s written. 8️⃣ What is Debouncing and Throttling? Debouncing → delays execution Throttling → limits execution rate 👉 Used for performance optimization. 9️⃣ What is Spread vs Rest operator? Spread → expands values Rest → collects values 👉 Same syntax, different use. 🔟 What is Prototype in JavaScript? Objects inherit properties via prototype chain. 👉 Core concept behind JS inheritance. 💡 JavaScript interviews test concepts, not syntax. 💪 One goal – SELECTION #javascript #Interview #questions #mostasking #important #save

If you're preparing for a JavaScript interview, one question always comes up: “Do I really need to practice small JS coding questions?” My answer: Yes — but smartly. I created this GitHub repo to practice and revise common JavaScript coding questions that are often asked in interviews: 🔗 GitHub Repo: https://lnkd.in/gxAXf_v3 This repo includes practice questions on: Arrays Strings Objects Closures Debounce / Throttle Promises Memoization Output-based questions Common logic building problems Examples: Two Sum Remove Duplicates Find Duplicates Palindrome Check Anagram Check Flatten Nested Array Implement Promise.all Deep Clone Object First Non-Repeating Character So… are these enough for interviews? Not fully. But they are very important because they help you build: problem-solving speed JavaScript fundamentals confidence in writing clean code pattern recognition during interviews What else should you practice apart from this? If you are targeting frontend / JavaScript developer roles, also practice: ✅ DOM manipulation ✅ Event bubbling / capturing ✅ Async JS (Promise, async/await, event loop) ✅ Closures, hoisting, scope, prototypes ✅ Polyfills ✅ Array / object methods ✅ Machine coding / small frontend tasks ✅ Output-based and debugging questions ✅ Basic DSA patterns in JavaScript My suggestion: Use these small coding questions for daily revision. Even solving 2–3 questions a day can improve your logic and interview confidence a lot. If you're also preparing for JavaScript / frontend interviews, feel free to check out the repo and use it for practice. ⭐ If you find it useful, do star the repo. #javascript #webdevelopment #frontenddeveloper #interviewpreparation #codinginterview #js #developers #github #100DaysOfCode #softwareengineer

🚀 JavaScript Interview Must-Know: Closures Explained Simply If you’re preparing for a JavaScript interview, one concept you cannot ignore is Closures. 👉 What is a Closure? A closure is created when a function remembers variables from its lexical scope even after the outer function has finished executing. Sounds confusing? Let’s simplify 👇 function outer() {  let count = 0;  return function inner() {   count++;   console.log(count);  }; } const counter = outer(); counter(); // 1 counter(); // 2 counter(); // 3 👉 What’s happening here? inner() function still has access to count Even though outer() has already finished execution This is called a closure 💡 Why Interviewers Love This Question? Because it tests: Scope understanding Memory behavior Real-world problem solving 🔥 Real Use Cases: Data hiding (private variables) Function factories Event handlers Callbacks & async code 👉 Pro Tip: Closures are heavily used in frameworks like React (hooks work on similar concepts) 💬 If you’re learning JavaScript for interviews, master this concept — it appears in almost every technical round. #JavaScript #WebDevelopment #MERNStack #Frontend #CodingInterview #100DaysOfCode #Developers #LearnToCode #IrfanMeraj

ADVANCED JAVASCRIPT CONCEPTS FOR INTERVIEWS #SaveForLater #MohitDecodes If you're preparing for JavaScript interviews, these are must-know concepts that can seriously level up your understanding 👇 -- Callback Function passed as an argument & executed later → leads to callback hell -- Promise Handles async operations → resolve / reject (cleaner than callbacks) -- Async/Await Syntactic sugar over promises → makes async code look synchronous -- Strict Mode ("use strict") Catches silent errors & enforces cleaner coding practices -- Higher Order Functions Functions that take/return other functions → map, filter, reduce -- Call, Apply, Bind Control the value of this → powerful for context handling -- Scope Block | Function | Global → defines variable accessibility -- Closures Access outer function variables even after execution -- Hoisting Variables & functions moved to top before execution -- IIFE Immediately Invoked Functions → avoid global pollution -- Currying Convert multi-arg function → chain of single-arg functions -- Debouncing Delay execution → improves performance (search inputs, etc.) -- Throttling Limit execution rate → useful in scroll/resize events -- Polyfills Add support for modern features in older browsers 💡 These are not just interview questions — they define how JavaScript actually works under the hood. Pro Tip: Don’t just read — implement each concept with code! 💬 Was this helpful? 🔖 Save for later 📢 Follow for more: Mohit Kumar #JavaScript #Frontend #WebDevelopment #ReactJS #InterviewPrep #Coding #100DaysOfCode