General Node.js Knowledge: What is Node.js, and how does it differ from traditional server-side environments? Explain the event-driven architecture of Node.js. How does Node.js handle asynchronous operations? JavaScript and ES6: What are closures in JavaScript, and how do they relate to Node.js? Explain the difference between let, const, and var in JavaScript. What are arrow functions, and how are they used in Node.js development? Node.js Core Modules: Name some core modules in Node.js and explain their purpose. How do you use the fs module for file operations in Node.js? What is the http module, and how do you create an HTTP server in Node.js? Express.js: What is Express.js, and why is it commonly used with Node.js? Explain middleware in Express.js. Provide examples of middleware functions. How do you handle routing in Express.js? RESTful APIs: What are RESTful APIs, and how do you design them? How do you implement CRUD operations (Create, Read, Update, Delete) in a RESTful API using Express.js? Database Interactions: How do you connect to a database in Node.js? Explain the differences between SQL and NoSQL databases. Which one would you choose for a Node.js project and why? How do you perform database queries asynchronously in Node.js? Error Handling: What are common error handling techniques in Node.js? How do you handle errors in asynchronous code in Node.js? What is the difference between synchronous and asynchronous error handling? Testing: What are unit tests, integration tests, and end-to-end tests? How do you write them in Node.js? Explain the use of testing frameworks like Mocha, Jest, or Jasmine in Node.js development. Security: What are some common security vulnerabilities in Node.js applications, and how do you mitigate them? How do you handle user authentication and authorization in Node.js applications? Explain the concept of Cross-Site Scripting (XSS) and how to prevent it in Node.js applications. Performance Optimization: What are some techniques for optimizing the performance of Node.js applications? How do you monitor and debug performance issues in Node.js applications? Explain the concept of clustering in Node.js and when you would use it. These questions cover a range of topics relevant to Node.js development and can help assess a candidate's knowledge and expertise in the field. Depending on the specific job requirements and level of experience, interviewers may delve deeper into certain areas or ask additional questions.