A user sends invalid input data to your API. What status code should you return?
You need real-time validation while a user types. Which approach is ideal?
Why should integration tests use a test database?
Why are Docker containers lighter than VMs?
Before deploying a full-stack app, what is MOST critical?
Your Node.js app becomes slow under heavy traffic. Which Node.js module can help you scale?
Why is Vercel ideal for React and Next.js apps?
CSS Performance
A webpage feels slow due to heavy style recalculations. Which CSS practice helps improve performance?
A deeply nested component needs access to global authentication data. What is the BEST solution?
Your query performance is slow on large datasets. What improves it?
What problem does Socket.IO solve on top of WebSockets?
You are building a form for a public-facing application. To improve accessibility for screen readers, which HTML practice is MOST appropriate?
You want to automatically test both the request and the database response in an Express API. What tools are best?
What is the main role of GitHub Actions in a project?
You are building a real-time chat app. Why choose WebSockets over HTTP polling?
Why should secrets be stored in environment variables?
A bug occurs because a variable declared inside a loop is accessible outside it. Which keyword likely caused this?
Your pipeline fails if tests don’t pass. What principle does this enforce?
You are fetching data from an API and need to handle errors gracefully. Which approach is best?
Why should JWTs NOT be stored in localStorage for sensitive apps?
A function runs repeatedly during scroll events, causing lag. What should you implement?
You need to create a responsive layout where items wrap automatically based on screen size. Which CSS solution is best?
You want to release breaking API changes without affecting existing clients. What’s the best approach?
You need strict relationships and transactions for financial data. Which database should you choose?
A client wants to update only one field of a resource. Which HTTP method is most appropriate?
React Rendering
Your React component re-renders unnecessarily when props don’t change. What should you use?
Why use Docker in development?
In an MVC application, where should business logic reside?
You want to log every incoming request globally. Where should this logic go?
You are storing chat messages with varying schemas. Which database fits best?
