Comment by eyelidlessness

3 years ago

There are already JS solutions for scroll-based behaviors and styling (the actual scroll event, IntersectionObserver which performs better because it’s non-blocking and batched).

Scroll Timeline is a CSS-only solution. And it’s kind of a misnomer, it’s really a position-based styling mechanism that can be used without any scrolling at all[1].

At minimum, this API will allow existing functionality that relies on scroll position to perform better (first by integrating with the rest of the CSS-paint pipeline, next IIUC by offloading to GPU where possible), which itself is welcome. But it also unlocks a bunch of other styling possibilities that are either impossible without JS or rather brittle.