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