Event Loop

Summary

The mechanism that lets single-threaded Node.js handle thousands of concurrent connections by delegating I/O work and processing callbacks as they complete, instead of blocking.

How to Learn This

1Log the order of `setTimeout`, `Promise.then` and synchronous code to see the event loop phases.
2Learn the difference between the microtask queue (Promises) and macrotask queue (setTimeout).
3Understand why a long synchronous computation blocks the entire event loop.

V8 Engine

Non-Blocking I/O

More topics in Node.js Fundamentals

Node.js Runtime V8 Engine Non-Blocking I/O Modules (CommonJS vs ESM)NPM & Package Management package.json Async Programming Callbacks Promises Async/Await Streams Buffers File System (fs)Process & Environment Variables Event Emitter Child Processes Clustering

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