Qustion-list

Senior Software Engineer Interview Preparation Questions

1. JavaScript (30 Questions)

1. Explain event delegation in JavaScript.
2. What is the difference between == and === in JavaScript?
3. Explain closures and provide a use case.
4. How does the JavaScript event loop work?
5. What is hoisting in JavaScript?
6. Explain the difference between var, let, and const.
7. What is a promise, and how does it work?
8. How does async/await work internally?
9. Explain the difference between call, apply, and bind.
10. What is the prototype chain in JavaScript?
11. What are weak maps and weak sets?
12. How does garbage collection work in JavaScript?
13. What is memoization, and how can you implement it?
14. Explain the difference between function declaration and function expression.
15. What are ES6 modules, and how do they work?
16. How do you implement currying in JavaScript?
17. What is the difference between shallow and deep copy?
18. How does debouncing and throttling work?
19. What are generator functions in JavaScript?
20. Explain the difference between spread and rest operators.
21. How does JavaScript handle asynchronous operations?
22. What is tail call optimization?
23. Explain the concept of a pure function.
24. How do you prevent race conditions in JavaScript?
25. What are JavaScript proxies?
26. Explain the concept of Object.freeze.
27. What is the difference between async.series and async.parallel?
28. How does optional chaining work?
29. Explain BigInt in JavaScript.
30. How does the temporal dead zone (TDZ) work in JavaScript?

2. TypeScript (30 Questions)

1. What are the key differences between TypeScript and JavaScript?
2. Explain the concept of type inference in TypeScript.
3. How does TypeScript handle optional properties?
4. What are utility types in TypeScript?
5. Explain the difference between type alias and interface.
6. What is type assertion in TypeScript?
7. How do you enforce strict null checks in TypeScript?
8. What are mapped types in TypeScript?
9. How does TypeScript support generics?
10. Explain discriminated unions in TypeScript.
11. What is the keyof operator?
12. How do you create a readonly property in TypeScript?
13. What are index signatures in TypeScript?
14. Explain the difference between unknown and any.
15. How does TypeScript support mixins?
16. What is an ambient module in TypeScript?
17. How do you use TypeScript with React?
18. What is a tuple in TypeScript?
19. Explain how TypeScript compiles to JavaScript.
20. What is declaration merging in TypeScript?
21. How do you use enums in TypeScript?
22. Explain how namespaces work in TypeScript.
23. How do you define a custom type guard?
24. What is the difference between extends and implements?
25. How do you use the never type in TypeScript?
26. How does TypeScript handle function overloading?
27. What are module augmentation and declaration files?
28. What is the purpose of TypeScript’s Partial utility?
29. How do you configure tsconfig.json for best practices?
30. What is the difference between public, private, and protected access modifiers?

7. Microservices (30 Questions)

1. What are microservices, and how do they differ from monolithic architectures?
2. What are the key benefits of using microservices?
3. How do microservices communicate with each other?
4. What is API Gateway in microservices architecture?
5. How do you handle authentication and authorization in microservices?
6. What are the challenges of implementing microservices?
7. How do you design a scalable microservices architecture?
8. What is service discovery in microservices?
9. What are distributed transactions, and how are they handled in microservices?
10. What is the role of containerization in microservices?
11. How do you handle data consistency across microservices?
12. What is circuit breaking in microservices?
13. What are the best practices for deploying microservices?
14. How do you monitor microservices?
15. What is the saga pattern in microservices?
16. How do you handle logging in microservices?
17. How does event-driven architecture work in microservices?
18. What is the difference between synchronous and asynchronous communication in microservices?
19. How do you implement API versioning in microservices?
20. How does Kubernetes help manage microservices?
21. How do you ensure security in microservices?
22. What is CQRS (Command Query Responsibility Segregation) in microservices?
23. How do you implement microservices with serverless computing?
24. What are some common pitfalls when implementing microservices?
25. What is the role of a service mesh in microservices?
26. How do you optimize performance in a microservices architecture?
27. What is the 12-factor app methodology in microservices?
28. How do you handle failures in a microservices system?
29. What are idempotent requests, and why are they important in microservices?
30. How do you ensure backward compatibility in microservices?

8. System Design (30 Questions)

1. How would you design a URL shortening service like Bit.ly?
2. How do you scale a system to handle millions of users?
3. What is load balancing, and how does it work?
4. How do you design a high-availability system?
5. How do you implement rate limiting in a web service?
6. What is the CAP theorem, and how does it affect system design?
7. How would you design a distributed cache system?
8. What is the difference between vertical and horizontal scaling?
9. How do you ensure data consistency in distributed systems?
10. How would you design a messaging queue system?
11. How do you handle database sharding?
12. What are the best practices for designing a RESTful API?
13. How do you optimize a system for high write throughput?
14. What are the key considerations when designing a file storage system?
15. How do you ensure security in a large-scale system?
16. How do you handle traffic spikes in a system?
17. What are eventual consistency and strong consistency?
18. How do you design a real-time chat application?
19. What is the difference between RPC and REST in system design?
20. How would you design a recommendation system?
21. What is a distributed system, and how does it work?
22. How do you design a content delivery network (CDN)?
23. What is the difference between SQL and NoSQL in system design?
24. How do you handle failover in system design?
25. What are leader election algorithms in distributed systems?
26. How do you design a logging and monitoring system?
27. How do you handle data replication across multiple regions?
28. What are micro-frontends, and how do they relate to system design?
29. How do you design a scalable search engine?
30. How do you balance trade-offs in system design decisions?

3. Node.js (30 Questions)

1. How does the Node.js event loop work?
2. What are the differences between process.nextTick() and setImmediate()?
3. How does clustering work in Node.js?
4. Explain the difference between synchronous and asynchronous file operations in Node.js.
5. How do you handle errors in async/await in Node.js?
6. What is middleware in Express.js?
7. How do you handle authentication in a Node.js application?
8. What is the purpose of the buffer class in Node.js?
9. How does streaming work in Node.js?
10. Explain the concept of worker threads in Node.js.
11. What is the difference between spawn, exec, and fork in Node.js?
12. How do you optimize the performance of a Node.js application?
13. What are the different types of timers in Node.js?
14. How do you prevent memory leaks in a Node.js application?
15. How do you implement rate limiting in Express.js?
16. What is CORS, and how do you enable it in Express.js?
17. Explain how JWT authentication works in a Node.js API.
18. How does the require() function work in Node.js?
19. What is the purpose of the package.json file in a Node.js project?
20. How do you manage dependencies in a Node.js application?
21. What is PM2, and how does it help in running Node.js applications?
22. How do you implement WebSockets in Node.js?
23. What are microservices, and how can they be implemented in Node.js?
24. How does logging work in Node.js?
25. How do you secure a Node.js application?
26. What are some common debugging techniques in Node.js?
27. How do you handle database connections efficiently in Node.js?
28. Explain how Node.js interacts with databases like MongoDB and PostgreSQL.
29. What are some common performance bottlenecks in Node.js applications?
30. How do you use async_hooks in Node.js?

4. SQL (30 Questions)

1. Write a query to find the second highest salary from an employee table.
2. How do you optimize a SQL query for performance?
3. What are different types of joins in SQL?
4. What is the difference between UNION and UNION ALL?
5. What is an index in SQL, and how does it work?
6. How do you detect and resolve deadlocks in SQL databases?
7. Explain the ACID properties in SQL.
8. How do you implement pagination in SQL?
9. What is a stored procedure, and how is it used?
10. Explain the difference between clustered and non-clustered indexes.
11. How do you prevent SQL injection attacks?
12. What is the difference between DELETE and TRUNCATE?
13. Explain window functions in SQL.
14. How do you find duplicate records in a table?
15. What is a foreign key constraint in SQL?
16. How do you optimize complex SQL queries?
17. How do transactions work in SQL?
18. What is a Common Table Expression (CTE)?
19. How do you perform a full outer join?
20. What is normalization in SQL?
21. How do you perform recursive queries in SQL?
22. Explain the difference between a primary key and a unique key.
23. How do you retrieve the nth highest salary using SQL?
24. What is indexing, and when should you use it?
25. How do you handle NULL values in SQL?
26. What is database partitioning, and why is it used?
27. How do you measure database query performance?
28. What is a materialized view?
29. How do you perform an EXPLAIN plan in SQL?
30. What is the difference between INNER JOIN and OUTER JOIN?

3. React.js (30 Questions)

1. What are React hooks, and how do they work?
2. Explain the difference between functional and class components.
3. What is the virtual DOM, and how does React use it?
4. How does React handle reconciliation?
5. What is the difference between useState and useReducer?
6. How do you optimize React performance?
7. What are React portals, and when would you use them?
8. Explain the useEffect hook and its dependencies.
9. What is React context, and how does it work?
10. How does React handle state management without Redux?
11. What are React fragments, and why are they useful?
12. What is the difference between controlled and uncontrolled components?
13. How does React handle events compared to vanilla JavaScript?
14. What is server-side rendering (SSR) in React?
15. How does React lazy loading work?
16. Explain how error boundaries work in React.
17. What is the purpose of React.memo?
18. How does React handle hydration in Next.js?
19. How can you implement code splitting in React?
20. What are React refs, and how do you use them?
21. How do you implement authentication in a React app?
22. How does React Router work?
23. What is the purpose of the useRef hook?
24. Explain the difference between shallow rendering and deep rendering.
25. How do you test React components using Jest and React Testing Library?
26. What are higher-order components (HOCs), and how do they work?
27. What are the lifecycle methods in class components?
28. How does React handle concurrent rendering?
29. How do you optimize rendering in React applications?
30. What are custom hooks, and when should you use them?