With access to this method, you can parse any text document and turn it into some form of CSS. Think typescript for CSS or even SASS, but that compiles automatically in the browser as fast as a regular CSS document would load. CSS Properties and Values API This allows developers to create custom CSS properties, for instance, creating a property called font-awesomeness with values like fabulous, ok, and meh that translate to real renderable objects.
It lets you literally draw anything on the screen anywhere, think Canvas or SVG, only it renders before either of those, and you can render in any element border or background.
The implications for having access to such APIs are great for web performance as a whole. You can draw anything to the screen before anything else loads as fast as CSS, creating animations outside the current window’s context asynchronously. Having the ability to perform all of this without having to worry about which browser the user is utilizing is huge. It will reduce the weight of web applications that have to polyfill for unsupported browsers and get rid of bulky frameworks that must wait for the first browser render and slow pre- and post-processors.
Here are some examples from Google Chrome Labs