Mastering JavaScript Fundamentals for Interviews

📌 𝗝𝗮𝘃𝗮𝗦𝗰𝗿𝗶𝗽𝘁 & 𝗥𝗲𝗮𝗰𝘁 𝗜𝗻𝘁𝗲𝗿𝘃𝗶𝗲𝘄 𝗖𝗵𝗲𝗰𝗸𝗹𝗶𝘀𝘁 — 𝗦𝗮𝘃𝗲 𝗧𝗵𝗶𝘀 𝗙𝗼𝗿 𝗟𝗮𝘁𝗲𝗿 🚀 #Day33 If you're preparing for interviews, focus on: 🧠 Core JS Fundamentals ⚡ Async & Event Loop 🧩 Array/Object Logic 🏗 Advanced Concepts (Prototype, Bind, Debounce) 💻 Coding Without Built-ins ⚛️ React Hooks & Architecture 🚀 React Native New Architecture (Fabric, TurboModules, Hermes) Master fundamentals. Practice logic daily. Understand architecture deeply. 📌 Save this for your next interview round. Follow Arun Dubey for more related content! #JavaScript #FrontendDevelopment #ReactJS #WebDevelopment #Interviewquestions #CodingInterview

𝗥𝗲𝗮𝗰𝘁 𝗝𝗦 𝗜𝗻𝘁𝗲𝗿𝘃𝗶𝗲𝘄 𝗤𝘂𝗲𝘀𝘁𝗶𝗼𝗻𝘀 — 𝗖𝗼𝗺𝗽𝗹𝗲𝘁𝗲 𝗚𝘂𝗶𝗱𝗲 𝗳𝗼𝗿 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗲𝗿𝘀 Prepare for your next frontend interview with the most important React JS interview questions. This guide covers core concepts, hooks, state management, lifecycle methods, performance optimization, component architecture, and real-world scenarios asked by top companies. #ReactJS #FrontendDeveloper #WebDevelopment #JavaScript #ReactInterview #CodingInterview #TechInterview #SoftwareDeveloper #ReactHooks #LearnReact

Most developers think they understand async JavaScript… until interviews expose the gaps. Here’s the truth 👇 JavaScript is single-threaded, but it handles async work using: - Call Stack - Web APIs - Callback Queue - Event Loop The biggest mistake I made earlier: I used async/await without truly understanding what happens behind the scenes. Example: setTimeout(() => console.log("A"), 0); Promise.resolve().then(() => console.log("B")); console.log("C"); Output? 👉 C → B → A Why? Because: - Synchronous code runs first - Microtasks (Promises) run next - Macrotasks (setTimeout) run last This understanding alone can: ✔ Help you debug complex issues ✔ Improve performance decisions ✔ Crack frontend interviews Currently diving deeper into: - Promises & chaining - Currying & composition - Advanced JS patterns If you're preparing for frontend interviews, this is a must-master area. #javascript #frontend #webdevelopment #softwareengineering #remotework

Most developers think they understand async JavaScript… until interviews expose the gaps. Here’s the truth 👇 JavaScript is single-threaded, but it handles async work using: - Call Stack - Web APIs - Callback Queue - Event Loop The biggest mistake I made earlier: I used async/await without truly understanding what happens behind the scenes. Example: setTimeout(() => console.log("A"), 0); Promise.resolve().then(() => console.log("B")); console.log("C"); Output? 👉 C → B → A Why? Because: - Synchronous code runs first - Microtasks (Promises) run next - Macrotasks (setTimeout) run last This understanding alone can: ✔ Help you debug complex issues ✔ Improve performance decisions ✔ Crack frontend interviews Currently diving deeper into: - Promises & chaining - Currying & composition - Advanced JS patterns If you're preparing for frontend interviews, this is a must-master area. #javascript #frontend #webdevelopment #softwareengineering #remotework

🟢 Node.js trick Interview Question process.nextTick() vs setImmediate() — who wins the race? Both promise immediate execution. But Node schedules them very differently. 🧠 process.nextTick() • Runs right after the current operation finishes • Executes before the event loop continues • Higher priority • Can block the event loop if overused It jumps the queue. ⚡ setImmediate() • Runs in the check phase of the event loop • Executes in the next iteration • Lower priority than nextTick It waits for its turn. Example: setImmediate(() => { console.log("setImmediate") }); process.nextTick(() => { console.log("nextTick"); }): Output: nextTick setImmediate Even though setImmediate sounds faster 😄 This question isn’t about syntax. It tests understanding of: • Event loop phases • Task prioritization • Node’s internal scheduling Same language. Different execution model. #NodeJS #BackendDevelopment #EventLoop #JavaScript #TechInterview

🚀 𝐅𝐫𝐨𝐧𝐭𝐞𝐧𝐝 𝐈𝐧𝐭𝐞𝐫𝐯𝐢𝐞𝐰 𝐒𝐞𝐫𝐢𝐞𝐬 – 𝐃𝐚𝐲 𝟕 𝐀𝐟𝐭𝐞𝐫 𝐠𝐢𝐯𝐢𝐧𝐠 𝟓𝟎+ 𝐟𝐫𝐨𝐧𝐭𝐞𝐧𝐝 𝐢𝐧𝐭𝐞𝐫𝐯𝐢𝐞𝐰𝐬 𝐢𝐧 𝐭𝐡𝐞 𝐥𝐚𝐬𝐭 𝟑 𝐦𝐨𝐧𝐭𝐡𝐬, 𝐈 𝐫𝐞𝐚𝐥𝐢𝐳𝐞𝐝 𝐬𝐨𝐦𝐞𝐭𝐡𝐢𝐧𝐠: 𝐓𝐡𝐞 𝐭𝐡𝐢𝐬 𝐤𝐞𝐲𝐰𝐨𝐫𝐝 𝐢𝐬 𝐰𝐡𝐞𝐫𝐞 𝐦𝐚𝐧𝐲 𝐝𝐞𝐯𝐞𝐥𝐨𝐩𝐞𝐫𝐬 𝐠𝐞𝐭 𝐞𝐱𝐩𝐨𝐬𝐞𝐝. 𝐓𝐨𝐝𝐚𝐲’𝐬 𝐪𝐮𝐞𝐬𝐭𝐢𝐨𝐧 👇 🔹 What will this print? const obj = { name: "Swapnil", greet: function () { console.log(this.name); } }; obj.greet(); setTimeout(obj.greet, 0); Take 10 seconds. Think carefully. ✅ Correct Output: Swapnil undefined 🔥 Why? 1️⃣ First call: obj.greet(); Here, greet is called as a method of obj. So: 👉 this refers to obj Output: Swapnil 2️⃣ Second call: setTimeout(obj.greet, 0); Now we are passing the function reference. It is no longer called as a method of obj. So: 👉 "this" becomes the global object (or undefined in strict mode) And since the global object doesn’t have name, we get: undefined 🧠 What Interviewers Are Testing They want to see if you understand: -How "this" is determined -Call-site based binding -Difference between method call vs function call -How context can be lost Not memorized definitions. 🎯 Interview-Level Insight "this" depends on HOW a function is called, not where it is written. 🚀 Bonus Fix If you want it to work: setTimeout(obj.greet.bind(obj), 0); Now this will stay bound to obj. Tomorrow: We’ll break down 👉 Arrow Function vs Normal Function (this trap continues) Follow for Day 8 🔥 #javascript #frontend #interviewprep #webdevelopment #reactjs #coding #thiskeyword

Day-22 ✅ I used RxJS for 8 months and understood nothing. One real project changed that. Here are 20 questions that will do the same for you. If you're preparing for Angular interviews, RxJS WILL come up. Here are 20 questions you must be ready for: 1. What is RxJS and why does Angular use it? 2. What is the difference between an Observable and a Promise? 3. What is a Subject? How is it different from an Observable? 4. Difference between BehaviorSubject, ReplaySubject, and AsyncSubject? 5. What does switchMap do? When would you use it? 6. Difference between switchMap, mergeMap, concatMap, and exhaustMap? 7. What is debounceTime and what problem does it solve? 8. What is takeUntil and why is it important for memory management? 9. How do you unsubscribe from an Observable? What happens if you don't? 10. What is the async pipe and why is it better than manual subscription? 11. What is combineLatest? Give a real use case. 12. Difference between combineLatest, forkJoin, and zip? 13. What is catchError and how do you handle errors in an Observable stream? 14. What is a cold Observable vs a hot Observable? 15. What does shareReplay do and when should you use it? 16. How does HttpClient in Angular use RxJS internally? 17. What is tap operator used for? 18. Difference between filter, map, and pluck operators? 19. How would you implement a type-ahead search using RxJS? 20. What is scan operator? How is it different from reduce? Senior Angular interviews test you on Q6, Q12, and Q19 the hardest. Most people memorize definitions. Very few can explain with real examples. Which question from this list would you struggle with the most? Drop the number in the comments 👇 Save this post — you'll need it before your next interview. Repost to help someone who is currently preparing. Follow me for more Angular + SDET interview content every week. #Angular #RxJS #AngularDeveloper #AngularInterview #InterviewPrep #TypeScript #WebDevelopment #FrontendDeveloper #TechInterview #JavaScript #SoftwareEngineering #AngularTips

Javascript Event Loop - One of the Most Asked Interview Questions If you’ve ever prepared for a frontend interview, you’ve definitely come across this question: 👉 “How does the JavaScript Event Loop work?” Understanding the Event Loop is crucial because it explains how JavaScript handles asynchronous operations despite being single-threaded. 💡 In simple terms: JavaScript executes code using a call stack. Async tasks (like setTimeout, Promises, API calls) are handled by Web APIs Once completed, they move to callback queues. The Event Loop continuously checks and pushes tasks back to the call stack when it's empty. ⚡ Key concepts every developer should know: Call Stack Callback Queue Microtask Queue (Promises > setTimeout priority) Execution Order 🎯 Mastering this concept not only helps in interviews but also improves your ability to write efficient, non-blocking code. I’ve created a simple explanation (with examples) to make this concept easy to understand 👇 #JavaScript #Frontend #WebDevelopment #EventLoop #InterviewPrep #AsyncProgramming

𝗙𝗿𝗼𝗻𝘁𝗲𝗻𝗱 𝗜𝗻𝘁𝗲𝗿𝘃𝗶𝗲𝘄 𝗤𝘂𝗲𝘀𝘁𝗶𝗼𝗻𝘀 𝗧𝗵𝗮𝘁 𝗧𝗲𝘀𝘁 𝗥𝗲𝗮𝗹 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗲𝗿 𝗦𝗸𝗶𝗹𝗹𝘀 I recently gave a frontend technical interview and realized something important. Companies are no longer focusing on DSA puzzles for frontend roles. Instead, they test practical knowledge that real developers use every day. Here are some of the questions asked in my interview: 1️⃣ useOptimistic (React) How can you update the UI instantly before the API response arrives? 2️⃣ AbortController (JavaScript) How do you cancel API requests to avoid race conditions and memory leaks? 3️⃣ Synthetic Events (React) How does React handle events internally and how is it different from native DOM events? 4️⃣ Debouncing vs Throttling When should each be used in performance optimization? 5️⃣ Virtual DOM & Reconciliation How does React efficiently update the UI? These questions focus on real-world frontend development, not just theoretical coding problems. If you're preparing for frontend interviews, make sure you deeply understand these concepts. #FrontendDeveloper #ReactJS #JavaScript #WebDevelopment #FrontendInterview #ReactDeveloper #SoftwareEngineer #TechInterview #CodingInterview #FrontendEngineering #ReactHooks #WebPerformance #Programming #CodeWithGandhi 

🚨 JavaScript Interview Question What will be the output? const obj1 = { name: "Suman" }; const obj2 = { name: "Suman" }; console.log(obj1 == obj2); console.log(obj1 === obj2); At first glance, many developers expect the result to be true because both objects have the same values. But JavaScript compares objects by reference, not by value. Even if two objects contain identical properties, they are stored in different memory locations. So what do you think the output will be? #JavaScript #FrontendInterview #ReactJS #FrontendDeveloper #FrontendArchitecture #ProductBasedCompany