Senior Node Js Developer Interview Questions and Answers

Query to fetch employee names with their total project allocations from three related tables.

• Use SQL JOIN to combine Employee, Project, and Allocation tables.

• Group results by employee ID to count projects per employee.

• Example SQL query: SELECT e.name, COUNT(a.project_id) AS total_projects FROM Employee e LEFT JOIN Allocation a ON e.id = a.employee_id GROUP BY e.id;

• LEFT JOIN ensures employees with no project allocations are still included in the results.

Implement a queue class in JavaScript.

• Create a class with methods like enqueue, dequeue, isEmpty, and peek.

• Use an array to store the queue elements.

• Ensure proper error handling for dequeue on an empty queue.

A chat application system design involves real-time messaging, user authentication, message storage, and scalability.

• Use WebSockets for real-time communication

• Implement user authentication and authorization

• Store messages in a database like MongoDB or Redis

• Consider using a message queue like RabbitMQ for handling message delivery

• Design for scalability by using load balancers and microservices

Designing a shopping portal system involves creating a platform for users to browse, search, and purchase products online.

• Implement user authentication and authorization for secure transactions

• Design a database schema to store product information, user data, and order history

• Develop a responsive front-end interface for users to navigate and interact with the portal

• Integrate payment gateways for seamless transactions

• Implement search and filter functionalities for users to easi...read more