[csswg-drafts] [scroll-animations] Mention design constraint of not blocking scrolling?

RByers has just created a new issue for 
https://github.com/w3c/csswg-drafts:

== [scroll-animations] Mention design constraint of not blocking 
scrolling? ==
Depending on exactly how your interpret it, the [avoiding 
cycles](https://wicg.github.io/scroll-animations/#avoiding-cycles) 
section implies that scrolling may need to block on JavaScript / 
layout.

For blink (and probably also at least Edge) that is a non-starter.  
Ensuring scrolling never blocks on the main thread has been our #1 
scroll performance effort for several years, we're unwilling to allow 
that without an explicit scary-sounding opt-in API and a mitigation 
strategy (eg. "intervention" that applies on  sites whose performance 
isn't good enough to permit a reasonable user experience on low end 
phones).

Is there agreement on this non-blocking design constraint for scroll 
animations?  If so, perhaps it's worth mentioning in the introduction 
somewhere?

/cc @majido @flackr @shans

Please view or discuss this issue at 
https://github.com/w3c/csswg-drafts/issues/819 using your GitHub 
account

Received on Monday, 19 December 2016 18:45:28 UTC