What is Node.js and where you can use it? Why use Node.js? How does Node.js work? Why is Node.js a single thread? Explain Node.js web application architecture. Difference between Javascript and Node.js How does Node.js handle concurrency? Explain callback, promises, and async-await in Node.js Explain callback hell in Node.js and how to avoid it? What are modules in Node.js? Explain the event loop and event-driven programming. Why Node is preferred over Java and PHP? What are the frameworks for Node.js? Explain EventEmitter in Node.js Explain Async and Sync functions/methods/API. List down the tasks which should be done asynchronously using the event loop? What are package.json and its significance? What are streams in Node.js? What is REPL on Node.js? Difference between fork and spawn methods? What is Buffer, Piping & Stream Chaining in Node.js What are test pyramids in Node.js Explain middlewares in Node.js Different types of HTTP requests, codes and it’s the significance List various Node.js timing functions. What is WASI in Node.js Explain control flow in Node.js How to import external libraries? Explain LIBUV in Node.js Explain URL module, require module and ES6 in Node.js Why does google use the V8 engine in Node.js What are global objects in Node.js Explain streams and types of streams available in Node.js What are passport and OAuth in Node.js How to read/create/delete and edit files in Node.js Explain the DNS lookup function in Node.js Difference between Node.js and Ajax? How Node.js overcomes the problem of blocking I/O operations Explain child threads and how Node.js handle child threads What is blocking code in Node.js Difference between cluster and worker_threads in Node.js How to resolve unhandled exceptions in Node.js Testing libraries for Node.js and why we need to assert library in Node.js How to convert existing callbacks to promises? How would you handle errors for async code in Node.js? Explain the difference between the nextTick() and the setImmediate() method. Explain the concept of stub in Node.js What are OAuth and its concept in Node.js? Explain JWT and its application in Node.js Explain the difference between readFile & createReadStream.