What Really Happens When You Run JavaScript?

In this talk, we’ll go beyond syntax and frameworks to demystify what the JavaScript engine actually does, from parsing and interpretation to JIT compilation, garbage collection, and the event loop. We’ll break down how modern engines like V8 execute your code, optimize performance, and handle asynchronous operations behind the scenes.

We’ll then connect the dots to frontend frameworks like React, explaining how features like the virtual DOM or component re-rendering play nicely (or not) with the engine’s internals. Finally, we’ll explore what it takes to build UI without JavaScript using WebAssembly and C++, and whether that’s a future worth chasing.