Q1. How does Node.js work internally?
Node.js works on a single-threaded event loop architecture. It uses non-blocking I/O operations through libuv library. When an I/O request is made, it doesn't wait for the response; instead, it registers a callback and continues processing other requests. When the I/O operation completes, the callback is executed by the event loop.
Q2. What is the event loop in Node.js?
The event loop is a mechanism that allows Node.js to perform non-blocking I/O operations despite being single-threaded. It continuously checks the callback queue and executes pending callbacks. It has multiple phases: timers, I/O callbacks, idle/prepare, poll, check, and close callbacks. This enables handling thousands of concurrent connections.
Q3. What is non-blocking I/O in Node.js?
Non-blocking I/O means that operations like file reading, database queries, or network requests don't block the execution of other code. Instead of waiting for the operation to complete, Node.js continues executing the next lines of code. When the operation finishes, a callback function is called to handle the result.
Q4. Is Node.js truly single-threaded?
The main event loop in Node.js runs on a single thread, but some operations like file system I/O, compression, and cryptography use worker threads from libuv's thread pool. So while JavaScript execution is single-threaded, some background tasks can be parallelized, making Node.js efficient for I/O operations.
Q5. Explain the role of libuv in Node.js.
libuv is a C library that provides the event loop and handles asynchronous I/O operations. It abstracts away platform-specific details and provides a consistent interface for file system, networking, and threading. libuv manages the thread pool, handles signals, and implements the event loop that powers Node.js's asynchronous capabilities.