async/await vs Promises in JavaScript

JavaScript Interview Question: What is Promise.race()? Answer: Promise.race() returns the result of the first promise that settles (resolved or rejected). Example: 𝘗𝘳𝘰𝘮𝘪𝘴𝘦.𝘳𝘢𝘤𝘦([𝘢𝘱𝘪𝘊𝘢𝘭𝘭(), 𝘵𝘪𝘮𝘦𝘰𝘶𝘵()]) Explanation: It is useful when implementing timeouts for API requests. Follow-up Interview Question: What happens if the first Promise rejects? Answer: The entire Promise.race() rejects immediately. #javascript #promises #AsyncProgramming #SoftwareEngineering

JavaScript Interview Question: What is the difference between Promises and Callbacks? Answer: Callbacks pass a function to execute after async operations. Promises represent the result of an async operation. Explanation: Promises provide: 1. better readability 2. error handling 3. chaining support Follow-up Interview Question: Why did callback hell occur? Answer: Because nested callbacks made code difficult to maintain. #javascript #AsyncProgramming #WebDevelopment #SoftwareEngineering

📝 JavaScript Interview Essentials: Closures & Debouncing Explained! 🚀 Ever feel like you understand a concept until an interviewer asks you to explain it? You’re not alone. Closures and Debouncing are two of the most "asked yet misunderstood" topics in JS. Here’s the "TL;DR" (Too Long; Didn't Read) version: 1️⃣ Closures: The "Function with a Memory" 🧠 A closure happens when a function "remembers" the variables from its outer scope, even after that outer function has finished running. Real-world use: Creating private variables or stateful functions (like a counter). Interview Tip: If they ask why we use them, mention Data Encapsulation. 2️⃣ Debouncing: The "Patience Filter" ⏳ Debouncing is a technique to limit how often a function gets called. It waits for a specific amount of "silence" before executing. Real-world use: Search bars! You don't want to hit the API on every single keystroke; you wait until the user stops typing for 300ms. Interview Tip: Mention it’s crucial for Performance Optimization and reducing server load. Which one did you find harder to learn when you started? Let’s discuss in the comments! 👇 #JavaScript #WebDevelopment #Frontend #CodingTips #SoftwareEngineering #Programming #ReactJS #CareerGrowth #TechInterview #WebDev #CleanCode

I built a free practice section for frontend interview prep and it's live now. Over the past few weeks, I've been curating and organizing frontend interview questions into a structured, topic-wise Q&A format. The questions cover areas like:  • Currying & Closures  • Promises & Async patterns  • DOM manipulation  • Observable & Reactive programming  • …and more Most of the questions are sourced from BFE.dev and GreatFrontEnd two excellent platforms for frontend practice. I've organized them by topic with detailed solutions so you can use this as a quick-reference guide or a structured study plan. Whether you're preparing for your next frontend interview or just want to sharpen your JavaScript fundamentals, I hope this helps. Check it out here: https://lnkd.in/d27Dg6e8 If you find it useful, feel free to share it with someone who's preparing. And if you have feedback or want me to cover a specific topic, drop a comment! #FrontendDevelopment #JavaScript #InterviewPrep #WebDevelopment #CodingInterview #React #OpenSource

Today’s Question: What is the difference between null and undefined? 🔍 This is one of the most common JavaScript interview questions. They might seem similar because they both represent "nothingness," but they have very different meanings in the engine. Take a look at the code in the screenshot below! 👇 ✅ The Simple Answer undefined: Means a variable has been declared but has not yet been assigned a value. It’s JavaScript’s default. null: Is an assignment value. It is used by developers to explicitly say a variable should be empty. 🔥 The Key Differences (Interview Breakdown): 1️⃣ Type Distinction 🧠 typeof undefined is "undefined". typeof null is "object". (Note: This is actually a long-standing bug in JavaScript, but it’s a favorite interview "gotcha"!) 2️⃣ Equality Comparison ⚖️ null == undefined is true (They are loosely equal in value). null === undefined is false (They are different types). 3️⃣ Mathematical Operations ➗ 1 + undefined results in NaN (Not a Number). 1 + null results in 1 (Because null is converted to 0 in math operations). ⚠️ Key Takeaway for Interviews: Think of undefined as a system-level missing value (uninitialized), and null as a program-level missing value (intentionally empty). 🎯 The One-Liner for Interviews: "undefined is the default value of an uninitialized variable, while null is an intentional assignment representing the absence of any object value." Stay tuned! I’ll be posting a new question every day at 6:00 PM. 🕕 Which one do you use more often to "clear" a variable? Let’s discuss in the comments! 👇 #JavaScript #WebDevelopment #InterviewPrep #Frontend #SoftwareEngineering #CleanCode #CodingChallenge #ProgrammingTips

💡 JavaScript Technical Interview Prep: What is Currying, and how do you implement it? The Answer: Currying is a functional programming technique that transforms a function expecting multiple arguments into a sequence of nested functions, each taking exactly one argument at a time. Instead of calling a function like sum(1, 2, 3), a curried version allows you to call it as sum(1)(2)(3). - Why is this useful? 1) Enhanced Reusability: It allows you to break down complex functions into smaller, more modular pieces. 2) Partial Application: You can pre-fill certain arguments of a function and generate a new, specialized function to reuse later. 3) Immutability: Currying does not mutate the original function; it safely returns a new one. #JavaScript #TechInterview

JavaScript Interview Question: How do you handle errors in Promises? Answer: Using .catch(). Example: 𝘧𝘦𝘵𝘤𝘩("/𝘢𝘱𝘪")  .𝘵𝘩𝘦𝘯(𝘳𝘦𝘴 => 𝘳𝘦𝘴.𝘫𝘴𝘰𝘯())  .𝘤𝘢𝘵𝘤𝘩(𝘦𝘳𝘳 => 𝘤𝘰𝘯𝘴𝘰𝘭𝘦.𝘦𝘳𝘳𝘰𝘳(𝘦𝘳𝘳)) Explanation: .catch() handles errors from any previous promise in the chain. Follow-up Interview Question: Can errors inside .then() be caught by .catch()? Answer: Yes. Explanation: Errors thrown inside .then() propagate to .catch(). #javascript #promises #ErrorHandling #WebDevelopment

JavaScript Interview Question: How do you cancel API requests in JavaScript? Answer: Using AbortController. Example: 𝘤𝘰𝘯𝘴𝘵 𝘤𝘰𝘯𝘵𝘳𝘰𝘭𝘭𝘦𝘳 = 𝘯𝘦𝘸 𝘈𝘣𝘰𝘳𝘵𝘊𝘰𝘯𝘵𝘳𝘰𝘭𝘭𝘦𝘳() 𝘧𝘦𝘵𝘤𝘩("/𝘢𝘱𝘪/𝘥𝘢𝘵𝘢", {  𝘴𝘪𝘨𝘯𝘢𝘭: 𝘤𝘰𝘯𝘵𝘳𝘰𝘭𝘭𝘦𝘳.𝘴𝘪𝘨𝘯𝘢𝘭 }) // 𝘤𝘢𝘯𝘤𝘦𝘭 𝘳𝘦𝘲𝘶𝘦𝘴𝘵 𝘤𝘰𝘯𝘵𝘳𝘰𝘭𝘭𝘦𝘳.𝘢𝘣𝘰𝘳𝘵() Explanation: AbortController allows you to cancel ongoing requests. Useful for: 1. search inputs (cancel previous queries) 2. component unmount 3. preventing race conditions Without it, outdated responses may overwrite newer data. Follow-up: Have you ever faced race condition bugs in API calls? #javascript #WebDevelopment #AsyncProgramming #FrontendDevelopment

📘 𝐉𝐚𝐯𝐚𝐒𝐜𝐫𝐢𝐩𝐭 𝐈𝐧𝐭𝐞𝐫𝐯𝐢𝐞𝐰 𝐌𝐨𝐝𝐮𝐥𝐞 (𝐁𝐚𝐬𝐢𝐜) -> Save this checklist, I hope it will be of great use in your next interview revision! 👇 𝐒𝐞𝐜𝐭𝐢𝐨𝐧 2: 𝐕𝐚𝐫𝐢𝐚𝐛𝐥𝐞𝐬 11. 𝐖𝐡𝐚𝐭 𝐢𝐬 𝐮𝐧𝐝𝐞𝐟𝐢𝐧𝐞𝐝? -> JavaScript's default value is when nothing is assigned. This is a default behavior of JavaScript. If you have declared a variable (var age;) but have not given a value, JavaScript will automatically call it undefined. 12. 𝐖𝐡𝐚𝐭 𝐢𝐬 𝐍𝐚𝐍? -> Not a Number — invalid number result. This comes when you do something wrong while doing math. Example: If you multiply your name by 10 ("Sohan" * 10), JavaScript will say—brother, this is not a number, so the output will be NaN. 13. 𝐖𝐡𝐚𝐭 𝐢𝐬 𝐧𝐮𝐥𝐥? -> Intentionally assigning an empty value. You do this intentionally. When you want a variable to be empty now, and later the data will come, then you set age = null; yourself. 14. 𝐖𝐡𝐚𝐭 𝐢𝐬 𝐜𝐨𝐧𝐜𝐚𝐭𝐞𝐧𝐚𝐭𝐢𝐨𝐧? -> Adding two strings or concatenating two texts. For example: "Hello " + "World". 15. 𝐖𝐡𝐚𝐭 𝐢𝐬 𝐈𝐧𝐟𝐢𝐧𝐢𝐭𝐲? -> When a number is divided by 0. 50/0 result infinity. 16.𝐇𝐨𝐰 𝐭𝐨 𝐚𝐬𝐬𝐢𝐠𝐧 𝐝𝐚𝐭𝐚 𝐭𝐨 𝐚 𝐯𝐚𝐫𝐢𝐚𝐛𝐥𝐞? / 𝐇𝐨𝐰 𝐭𝐨 𝐚𝐬𝐬𝐢𝐠𝐧 𝐚 𝐯𝐚𝐫𝐢𝐚𝐛𝐥𝐞 𝐝𝐚𝐭𝐚? -> let x; x = 10; 17. 𝐕𝐚𝐫𝐢𝐚𝐛𝐥𝐞 𝐢𝐬 𝐩𝐫𝐢𝐦𝐢𝐭𝐢𝐯𝐞 𝐨𝐫 𝐧𝐨𝐧-𝐩𝐫𝐢𝐦𝐢𝐭𝐢𝐯𝐞? -> Primitive (stores single data of single value) #DotNet #AspNetCore #MVC #FullStack #SoftwareEngineering #ProgrammingTips #DeveloperLife #LearnToCode #JavaScript #JS #JavaScriptTips #JSLearning #FrontendDevelopment #WebDevelopment #CodingTips #CodeManagement #DevTools

Solving String Patterns on Day 219 Today Today I spent my time working on string manipulation problems using JavaScript. I focused on two very common interview patterns which are Palindromes and Anagrams. For the Valid Palindrome problem I used the two-pointer technique. This involves cleaning the string to remove non-alphanumeric characters and then comparing letters from the start and the end. This approach is very efficient because it only goes through the string once. For the Valid Anagram problem I practiced three different solutions. The first way was using a standard JavaScript object to count the frequency of each character. The second way was using the Map constructor for better performance with different key types. The most optimized way I learned was using a fixed-size array of 26 elements. Since we only deal with lowercase English letters an array is much faster than a hash map and uses constant extra space. Learning these different ways to solve the same problem helps me understand how to balance time and memory. It is not just about getting the right answer but finding the best way to get there. I solved these LeetCode questions today: 125. Valid Palindrome 242. Valid Anagram #DSAinJavaScript #365daysOfCoding #JavaScriptLogic #LeetCode #StringAlgorithms #CodingInterview #ProgrammingDaily #SoftwareEngineering #LogicBuilding #WebDevelopment #AlgorithmPatterns #JavaScriptDeveloper #ProblemSolving #CodeChallenge #TechLearning #DataStructures #FrontendDeveloper #SoftwareDevelopment #CodingSkills #DailyCoding