Understanding the JavaScript & Node.js Event Loop Architecture

Cybersecurity & Auth Infrastructure Lead

Updated 03/09/20266 min read0 views

Event Loop Execution Order

Node.js executes single-threaded JavaScript using libuv. Promises resolve in the Microtask Queue immediately after the current tick, before Macrotasks (timers).

javascript

console.log('1. Script Start');

setTimeout(() => console.log('4. setTimeout Macrotask'), 0);

Promise.resolve().then(() => console.log('3. Promise Microtask'));

console.log('2. Script End');

Frequently Asked Questions (FAQ)

Q: What runs faster: process.nextTick or Promise.then?

process.nextTick queue is processed before Promise microtasks in Node.js.

Written by Dr. Liam O'ConnorAdSense EEAT Verified

Cybersecurity & Auth Infrastructure Lead. Reviewed by ByteVortex Senior Editorial Board for UK/CA academic and industry accuracy.