10 API Call Questions for React Developers

I am 𝗵𝗶𝗿𝗶𝗻𝗴 you as a 𝗦𝗼𝗳𝘁𝘄𝗮𝗿𝗲 𝗘𝗻𝗴𝗶𝗻𝗲𝗲𝗿 if you can answer these 35 questions: 𝗝𝗮𝘃𝗮𝗦𝗰𝗿𝗶𝗽𝘁 𝗮𝗻𝗱 𝗥𝗲𝗮𝗰𝘁𝗝𝗦 (𝗙𝗿𝗼𝗻𝘁-𝗘𝗻𝗱)  - What is the difference between var, let, and const in JavaScript?  - How does the JavaScript event loop work?  - Explain closures in JavaScript with an example.  - What are promises, and how do they differ from async/await?  - What is the difference between shallow and deep copying in JavaScript?  - Explain the difference between == and === in JavaScript.  - What is the virtual DOM, and how does React use it?  - Explain the purpose of React hooks. How does useEffect work?  - What is the difference between controlled and uncontrolled components in React?  - What is the significance of key props in React lists? 𝗡𝗼𝗱𝗲𝗝𝗦 𝗮𝗻𝗱 𝗕𝗮𝗰𝗸𝗲𝗻𝗱 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗺𝗲𝗻𝘁  - What is event-driven architecture in NodeJS?  - How does NodeJS handle asynchronous operations?  - What are middleware functions in ExpressJS?  - How does authentication work in NodeJS? Explain JWT vs. OAuth.  - What are WebSockets, and when would you use them?  - What is the difference between monolithic and microservices architectures?  - How does NodeJS handle memory management? 𝗗𝗮𝘁𝗮𝗯𝗮𝘀𝗲𝘀 𝗮𝗻𝗱 𝗦𝘆𝘀𝘁𝗲𝗺 𝗗𝗲𝘀𝗶𝗴𝗻  - What is the difference between SQL and NoSQL databases?  - How does indexing work in databases?  - What are ACID properties in a database?  - How would you scale an API to handle millions of requests per second?  - Design elevator system  - Design a parking lot  - What is caching, and how does it improve performance?  - Design a rate limiter  - Design a logging system  - Design a pastebin/ code sharing app 𝗗𝗦𝗔  - Given an array, find the maximum sum of any contiguous subarray.  - Find the first non-repeating character in a string.  - Detect if a linked list contains a cycle.  - Merge k sorted linked lists into one sorted list.  - Given an arr and a number k, return the max in every sliding window of size k.  - Return the longest palindromic substring in a given string.  - Place k cows in n stalls to maximize the minimum distance between any two cows.  - Given course prerequisites, determine if all courses can be finished. 𝗡𝗼𝘁𝗲: These are important theoretical questions, but just knowing theory won’t get you hired.  - Write code, build real projects  - Work on problem-solving & DSA 𝗞𝗲𝗲𝗽𝗶𝗻𝗴 𝘁𝗵𝗶𝘀 𝗶𝗻 𝗺𝗶𝗻𝗱, 𝗜’𝘃𝗲 𝗽𝗿𝗲𝗽𝗮𝗿𝗲𝗱 𝗶𝗻 𝗗𝗲𝗽���𝗵 𝗦𝘆𝘀𝘁𝗲𝗺 𝗗𝗲𝘀𝗶𝗴𝗻 𝗚𝘂𝗶𝗱𝗲, 𝟰𝟬𝟬𝟬+ 𝗽𝗲𝗼𝗽𝗹𝗲 𝗮𝗿𝗲 𝗮𝗹𝗿𝗲𝗮𝗱𝘆 𝘂𝘀𝗶𝗻𝗴 𝗶𝘁. 𝗢𝗳𝗳𝗲𝗿𝗶𝗻𝗴 𝟰𝟬% 𝗼𝗳𝗳 𝗳𝗼𝗿 𝗮 𝗹𝗶𝗺𝗶𝘁𝗲𝗱 𝘁𝗶𝗺𝗲! 𝗚𝗲𝘁 𝘁𝗵𝗲 𝗚𝘂𝗶𝗱𝗲 𝗵𝗲𝗿𝗲: https://lnkd.in/dte69Z5N Use code 𝗦𝗗𝗘𝟰𝟬. Stay Hungry, Stay FoolisH!

Today, l'd like to share a recent interview experience for an Angular Developer position. The interviewer asked a practical scenario-based question: "Suppose inside a function you are asynchronously calling 10 different APIs, one after another. If one of the APIs is slow or throws an error, how would you handle the remaining API calls?" This question mainly tests your understanding of asynchronous programming, error handling, and performance optimization in JavaScript. In such cases, instead of calling APIs sequentially, we can use "Promise.all" or "Promise.allSettled" to manage multiple asynchronous calls efficiently. Example using "Promise.all": async function fetchAllData() { try { const results = await Promise.all([ fetch('api1'), fetch('api2'), fetch('api3'), // ... up to 10 APIs ]); const data = await Promise.all(results.map(res => res.json())); console.log('All API data:', data); } catch (error) { console.error('Error in one of the API calls:', error); } } ⚠️ Note: "Promise.all" will reject immediately if any single API fails. To handle all responses, even if some fail, use "Promise.allSettled": async function fetchAllDataSafely() { const results = await Promise.allSettled([ fetch('api1'), fetch('api2'), fetch('api3'), // ... up to 10 APIs ]); results.forEach((result, index) => { if (result.status === 'fulfilled') { console.log(`API ${index + 1} Success:`, result.value); } else { console.error(`API ${index + 1} Failed:`, result.reason); } }); } Using "Promise.allSettled" ensures that all API calls complete — successful or failed — without breaking the overall execution flow. It was a great question that tested both technical depth and the ability to think about real-world asynchronous programming #AngularDeveloper #JavaScript #AsyncProgramming #PromiseAll #PromiseAllSettled #FrontendDevelopment #WebDevelopment #InterviewExperience #TechLearning #Angular #ES6 #CodingInterview #DeveloperCommunity

🚀 Day 26 — Why Single Page Apps (SPAs) + Reactive Java = Super Smooth UX SPAs are everywhere: a single HTML loads, JS handles all real-time updates—no more waiting for page reloads. Tie in a Java backend (Spring Boot APIs) and the results are instant, interactive, and scalable. Here’s my SPA flow: React/Angular/Vue frontend handles routes, updates UI, fetches JSON from Java backend via REST Backend is non-blocking with Spring WebFlux or RxJava—ready for thousands of concurrent users Responsive, accessible, and tested for ultra-stable deployments Pro tips: Use lazy loading and smart routing for fast navigation Optimize API responses for pagination/filtering Profile and stress test reactive backend flows for spikes Have you built an SPA with a Java backend? Share your wins or best challenges! Next: Seamless authentication and secure sessions across SPAs. #Java #SPA #Reactive #API #SpringBoot #FullStackDeveloper #LearningJourney #BackendDeveloper #CloudNative #Kubernetes #Docker #AWS #Agile #JobsInGermany #GermanyJobs #GermanJobMarket #Stellenangebote #BerlinJobs #MunichJobs #HamburgJobs #FrankfurtJobs #CologneJobs #StuttgartJobs #JobSearch #JobSuche (German for Job Search) #NowHiring #Recruiting #OpentoWork #Career #NewJob #Opportunity #Employment #EnglishJobsGermany #RelocationGermany.

Is Angular enough to get a job in today’s market? 🤔 Let’s be honest — the frontend job market in 2025 is tough. Recruiters aren’t just looking for someone who “knows Angular.” They’re looking for someone who can build complete, scalable, and optimized applications. Yes, Angular is powerful — it gives you structure, TypeScript support, and enterprise-level reliability. But what really makes you job-ready today is how well you combine it with the ecosystem around it 👇 💡 Here’s what companies expect beyond Angular: • Strong understanding of TypeScript, RxJS, and Observables • Knowledge of API integration and error handling • Hands-on with State Management (NgRx, Akita, etc.) • Experience in Performance Optimization and Lazy Loading • Basic exposure to backend (Node.js / Python) • Ability to deploy projects on cloud / CI-CD pipelines • Writing clean, testable, and maintainable code So is Angular enough? ✅ If you know how to build and ship real-world apps with it — absolutely yes. ❌ If you’re just memorizing syntax and skipping the ecosystem — then not quite. Learn smart, build projects, stay updated — that’s what makes you “hireable.” Because the truth is, companies don’t hire frameworks — they hire problem solvers. 💪 #Angular #FrontendDevelopment #WebDevelopment #CareerAdvice #TechJobs #JavaScript Book 1: 1 session with me on Topmate: https://lnkd.in/gkhyGGf7

I’ve received a few kind messages recently offering frontend or JavaScript-heavy roles - and I truly appreciate the outreach! 😊 But I’d like to gently clear up a common mix-up: - I’m not looking for JavaScript roles. I’m actively seeking positions as a Java/Spring Backend Engineer. Yes, I can write JavaScript — vanilla, jQuery, Vue, Angular, React. In fact, I’ve even written over 100 educational articles about it (like these https://lnkd.in/epdTruPf ) back when I worked at a hosting company, and published some more in my personal blog. But here’s the thing: just because someone knows JavaScript doesn’t mean they want to work with it full-time. It’s like knowing how to bake bread — doesn’t mean you want to run a bakery! 🥖 Why do many engineers (myself included) choose Java over JavaScript for backend work? Here is a quick clarification about JavaScript vs Java 😊 — explained simply for non-techs: Purpose & Domain - Java = enterprise backend (payment processing, event-driven microservices, Kafka pipelines, Spark jobs). - JavaScript = frontend + light backend (dashboards, chat apps, user interactions). Long-Term Maintainability - Java’s strict types, mature tooling, and clear structure make large codebases easier to scale, test, and maintain over years. - JavaScript’s flexibility is great for startups — but in complex systems, “anything goes” can become “nothing works reliably.” Performance & Predictability - Java — built for high-load, mission-critical systems (banking, trading, Big Data). - JavaScript (in Node.js) is great for lightweight APIs or real-time UIs — but it’s single-threaded and dynamic, which can lead to hidden bugs and scaling limits under heavy load. They solve different problems — like comparing a scalpel (JS) to a hydraulic press (Java). Both useful — just not interchangeable. So if you’re hiring for: Java / Spring Boot, High-load backend, Big Data, Kafka, Cloud, Microservices  — then I’m your person. 💡 But if the role is heavy on React, Vue, or frontend logic — as much as I respect those stacks, it’s not where I want to focus my energy. Thanks for understanding — and for helping match the right talent to the right role! P.S. Open to 100% remote positions worldwide. No visa needed. P.P.S. Yes, I know — Java and JavaScript are as related as “car” and “carpet.” 😅 #Java #SpringBoot #BackendDeveloper #Hiring #TechRecruiting #JavaScript #RemoteWork #BigData #DevsOfLinkedIn 

🔥 Want to Level Up as a React Developer in 2025? Writing components is easy. Building fast, scalable, and maintainable React apps? That’s where great developers stand out. 💪 Here’s a skill roadmap that can take your React expertise from “I can build it” to “I can scale it.” 👇 1. Master State Management Don’t just rely on useState. Understand when and why to use tools like: -- Redux Toolkit for complex data flow -- Context API for lightweight shared state -- Zustand or Recoil for modern alternatives 2. Focus on Performance Make your components do more with less work: -- Use React.memo, useMemo, and useCallback smartly -- Split bundles using lazy loading -- Detect bottlenecks via React Profiler 3. Learn Design Patterns That Scale Stop repeating code — start reusing logic: -- Write Custom Hooks -- Explore HOCs and Render Props for flexible components 4. Go Beyond the Browser: SSR & Next.js -- Understand how server-side rendering and hydration boost SEO and first-load speed. -- Next.js makes this simpler than ever. 5. Bring TypeScript into the Mix -- Type safety = fewer runtime bugs. -- Work with interfaces, generics, and advanced types for a more reliable codebase. 6. Test Before You Ship A good React app is a tested React app. -- Use React Testing Library for unit tests -- Cypress or Playwright for end-to-end flows 7. Nail Your Tooling Setup Your tools are your workflow: -- Use Vite, Webpack, or Babel effectively -- Keep your code clean with ESLint and Prettier 8. Build Better Data Layers Fetching data efficiently matters: -- Try React Query or SWR for caching & revalidation -- Learn GraphQL with Apollo Client -- Handle real-time updates with WebSockets 9. Secure Your Application -- Authentication isn’t optional. -- Understand JWT, OAuth, and implement RBAC for user permissions. 10. Design for Scale Think architecture, not just components: -- Explore Monorepos (Nx, Turborepo) -- Micro-frontends for modular codebases -- Atomic Design for consistent UI systems 👉 Follow Sharad kumar for daily doses of tech wisdom, corporate realities, and relatable IT life. 🚀 #MERNStack #ReactJS #NodeJS #InterviewPreparation #JavaScript #FullStack #WebDevelopment #SoftwareEngineer #Learning #Hiring #Jobs #FresherJobs #TechTalks #Software

🚀 Full Stack Developers: The Bridge Between Ideas and Implementation In today’s tech world, full stack developers do more than just write code — they connect the entire system. From designing seamless front-end experiences using React or Angular, to building scalable backends with Node.js and Spring Boot, we live at the intersection of creativity and logic. But the real challenge (and thrill!) lies in balancing performance, scalability, and user experience — all at once. A true full stack mindset means: 🧠 Thinking like a designer when building interfaces ⚙️ Thinking like an engineer when designing APIs 🧩 Thinking like a strategist when integrating databases and cloud services It’s not just about knowing both ends — it’s about understanding how every layer impacts the user. 💬 What’s the most challenging part of full stack development for you — front-end optimization, backend scalability, or debugging across both ends? #FullStackDevelopment #WebDevelopment #ReactJS #NodeJS #JavaScript #TechCommunity #CodingJourney #SoftwareEngineering #SystemDesign #Microservices #TechInnovation #Microservices  #BackendDeveloper #Hiring #OpenToWork #TechJobs #ContractOpportunity #C2C #JavaJobs #JobSearch #TechHiring

Should you reject a Vue developer for a React role? It's tempting to filter for exact stack matches. "Must know React." Reject everyone else. (You're doing keyword screening again). Here's what happens when you optimize for framework expertise over assessing someone's fundamentals. We had a customer hire two developers. First one: React expert. Resume perfect. Knew hooks, context, suspense inside out. Second one: Vue developer hired through our platform after proving fundamentals through real-world assessments. Project started. Legacy client needed work on vanilla JavaScript and SASS. No frameworks. Just core web development. The React expert was stuck. Couldn't work without the framework. Struggled with basic DOM manipulation. Didn't understand CSS cascade without styled-components abstractions. The customer had to part ways with the candidate within like 2 months of hiring him. The Vue developer had overall skillset more broad and based on core development. He was able to pick up a new framework and work on the core of the sites in a week, opening PRs on day 1. Picked up the codebase in a week. Why? Strong fundamentals. Understood JavaScript deeply, not just Vue syntax. Knew CSS principles, not just utility classes. Could read any code and understand the underlying patterns. Framework-specific hiring creates fragility. Your stack will change. React today, something else in two years. Microservices mean different teams using different stacks. You can't limit yourself to "only React developers" when part of your system runs Angular and another uses Svelte. Strong developers learn frameworks quickly because they understand the fundamentals. Weak developers hide behind framework knowledge because they never learned the foundation. The difference: One memorized React patterns. The other understood component architecture, state management, and rendering principles that work in any framework. When tech stacks shift—and they will—the framework expert becomes obsolete. The fundamentals-first developer adapts. So, never filter for "5+ years React". Start testing this -- - Can they debug async JavaScript? - Do they understand closure and scope? - Can they write clean, maintainable code regardless of framework? Hire good developers, not tech specific ones. The best developers aren't React or Vue or Angular specialists. They're problem-solvers who happen to know frameworks. ------------------ If you’re a CEO/Founder of a Custom Software Development company, or have an Engineering team that resonates with these concepts, we’ve published a free guide on how to get strong tech hires. (also includes a free GPT-tool, a distinguished engineer that crafts technical questions for you). link in the comments 👇

Everyone’s talking about switching to React jobs. But no one’s talking about the fakers — and how to spot them. Faking 2–3 years of React experience with no real work behind them. Let’s be honest — fake experience is flooding the job market. Here’s what I’ve personally learned 👇 🚩 1. They know the *syntax*, not the *reason* You ask: “Why did you use useEffect here?” They say: “To fetch data.” But they can’t answer: - Why not inside the component body? - What happens if dependencies are wrong? - Did you use cleanup? Why or why not? 📌 **Real devs** explain behavior.   **Fakers** repeat definitions. 🚩 2. No debugging scars = no real dev work Every real React dev has gone through: - useEffect causing infinite loops   - Re-renders that tank performance   - A state update not reflecting due to stale closures   - “Can’t perform a React state update on an unmounted component” error Ask:   > “What was a tough bug you faced in production?”   > “How did you debug it?” If they say “I usually didn’t face issues” — they’re faking, bro. 🚩 3. Projects are shallow tutorial clones Github is full of: - Netflix clone   - Weather app   - Blog CMS   - No README, no routing, no deployment Ask: > “What are the folders in your app?”   > “How does state flow work across screens?”   > “What would you improve if you rebuilt this?” If they can’t walk you through it like it’s their baby — 🚨🚨 --- 🚩 4. Performance is not even on their radar React devs with real experience will mention: - `React.memo`, `useMemo`, `useCallback`   - Avoiding prop drilling   - List virtualization   - Lazy loading / Suspense   - Bundle splitting Fakers don’t even know what to measure. Ask: > “How do you avoid unnecessary re-renders?”   > “What tools do you use to profile performance?” If the answer is blank, so is their experience. 🚩 5. Vague work in real-world projects Everyone says: > “I worked on the dashboard”   > “I helped with the UI”   > “It was a team project” But real contributors can walk you through: - How data was fetched   - How state was handled   - How they debugged or optimized a feature   - Trade-offs they made in implementation Fakers go silent or switch to theory. 🚩 6. They avoid hands-on coding during interviews Real devs don’t love live coding either —   But they’re okay talking and coding through small problems. Fakers panic.   They fumble with basic array methods (`map`, `filter`, `reduce`).   They avoid the keyboard like it’s cursed. 💡 Pro tip: Ask them to build a mini search bar with debouncing live on CodeSandbox. ☑️ What to do if you're hiring or mentoring: ✔️ Ask “why” more than “what”   ✔️ Let them walk through their project architecture   ✔️ Push them gently to code or explain live   ✔️ Focus on thought process, not syntax perfection 🚫 This isn’t hate on career switchers.   I help people switch into React all the time.   But *faking experience* doesn’t help anyone. Don't skip the grind #frontend #react

���� Top Interview Questions: JavaScript Full Stack Edition 💻✨ Are you preparing for your next Full Stack Developer or JavaScript Engineering interview? Dive into the Top 50 JavaScript Full Stack Interview Questions & Answers — your complete guide to mastering both frontend and backend concepts like React, Node.js, Express, MongoDB, and more! ⚡ 🧠 What You’ll Learn: ✅ Core JavaScript, ES6+, and asynchronous programming concepts ✅ React, Node.js, Express, and MongoDB interview questions ✅ Hands-on coding examples with real-world scenarios ✅ Best practices for scalable web applications ✅ Perfect for MERN, MEAN, or any modern full stack interview 📖 Read the full guide here: 👉 https://lnkd.in/gKX9Xi65 💡 Why this matters: Full Stack Developers are among the most in-demand professionals in today’s tech world. Strengthen your technical foundation, sharpen your coding logic, and confidently crack your next big interview. 🚀 #TopInterviewQuestions #JavaScript #FullStackDeveloper #MERNStack #MEANStack #ReactJS #NodeJS #ExpressJS #MongoDB #FrontendDevelopment #BackendDevelopment #WebDevelopment #SoftwareEngineering #CodingInterviews #Programming #TechJobs #TechInterviews #AI #DataScience #DataEngineering #MachineLearning #ArtificialIntelligence #CloudComputing #SQL #Python #TechTalent #JobSearch #CareerGrowth #Hiring #InterviewPreparation #JobOpportunities #CareerDevelopment #TechIndustry #TechCareers #Innovation #CareerOpportunities #DigitalTransformation #TechTrends #FutureOfWork #Coding #LearnToCode #WomenInTech #RemoteJobs #InDemandSkills #JobAlert #TechCommunity #Engineering #JobHunt #CareerSuccess #UpSkilling #TechEcosystem #TechLife #CodingLife #AIandML #SoftwareDeveloper #CareerPath #Recruitment #TechWorld #JobReady #ComputerScience #AI #BigData #CyberSecurity #TechHiring #BackendDeveloper #Algorithms #DataStructures #OperatingSystems #DBMS #OOPS #Java #CPlusPlus #SystemDesign #TrendingNow #ITJobs #TechCareerPath