In my interview for a position requiring expertise in Node.js and Express.js, I was first asked to explain the core concepts of Node.js, including its event-driven architecture and non-blocking I/O. The interview then delved into Express.js, where I was required to describe middleware, routing, and error handling. Some specific questions included: "How do you set up a basic Express server?", "What are the different types of middleware in Express?", "How do you handle errors in Express?", and "Can you explain the process of connecting a Node.js application to a database?". Additionally, I was given a practical coding task to create a simple RESTful API using Node.js and Express.js, demonstrating my understanding of CRUD operations, routing, and middleware integration. The interview concluded with a discussion on security best practices for Node.js applications, including the use of environment variables, handling user authentication, and protecting against common vulnerabilities like SQL injection and cross-site scripting (XSS).