There’s a new web platform feature flighting in Chromium called Declarative Partial Updates. This proposal adds a new <?marker> element which enables out-of-order streaming of content. Rather than the traditional way of building the HTML you need on the server, or sending JSON down to a JavaScript framework, you can staple HTML onto the initial response and use the <template for=""> syntax to inject that content into the <?marker name=""> placeholder.

When Gareth previewed CSS: the bomb inside your inbox I was blown away. He could steal a login token with CSS alone, without having to recursively load another stylesheet for every character. Then I watched the browser wrestle with roughly 250 MB of CSS to recover a 12-character hex token. It worked. But such a large payload for 12 characters made me think there must be a better way.