Frontend internals
Web Platform
The browser is your stage. The event loop, the DOM, hydration, layout, paint.
Every web app you have ever used runs on the same platform — the browser. Underneath the framework of the week sits the same handful of mechanisms: an event loop that decides what runs when, a DOM that the browser parses and paints, a hydration handshake between server-rendered HTML and client JavaScript. These activities make those mechanisms visible. They are the things you reach for when a button feels slow and the framework can't tell you why.
Schedule setTimeout, Promise.then, requestAnimationFrame, and a synchronous CPU block. Step the loop and watch microtasks drain to exhaustion between every macrotask, rAF fire right before paint, and a 50ms sync block freeze the renderer cold.
Teaches: Phase 2 · Web Development