Topic

APIs

HTML, CSS, and JavaScript are the languages. The APIs are what the browser actually hands you to build with — the component model, the network, storage, and the observers that tell you what the page is doing. This section works through them one at a time.

Web Components
The platform's own component model: custom elements, shadow DOM, templates and slots, and the lifecycle that ties them together. Nine steps, each with a live demo you can open and take apart.
Client-Side Communication
Nine steps from what a plain <form> already does, through Ajax, XHR, and fetch, to the shapes that are not a request and a response. The client half of the story: what falls back, what is worth sending, and whether the answer can be trusted.
Storage and state — planned
Web Storage, IndexedDB, and the cache: what persists, where, for how long, and who else can read it.
Observers — planned
IntersectionObserver, ResizeObserver, MutationObserver — asking the browser to tell you when something changed instead of polling for it.