Programming
How JavaScript Works Behind the Scenes
A deep dive into the JavaScript engine, call stack, event loop and how things actually work.
May 25, 20256 min read
The Call Stack
JavaScript is single-threaded — it has one call stack and executes one thing at a time.
The Event Loop
The event loop is what allows JavaScript to perform non-blocking operations despite being single-threaded.
Example
console.log("1");
setTimeout(() => console.log("2"), 0);
console.log("3");
// Output: 1, 3, 2
Why This Matters
Understanding this helps you reason about async code, promises, and why certain bugs happen.
EngineJavaScript