24388 2014-01-24 23:25:06 +0000 Expose CSS-support API to Web Workers 2014-10-02 17:52:11 +0000 1 1 1 Unclassified CSS Conditional Rules unspecified PC All NEW P2 normal --- 1 jonas dbaron brunoaiss zcorpan public-css-bugzilla oldest_to_newest 99040 0 jonas 2014-01-24 23:25:06 +0000 We should expose the CSS-support API to Web Workers. This is going to be especially important for ServiceWorkers who will want to decide which resources to download based on capabilities of the UA. So for example if a UA doesn't support some flexbox, the website might want to cache an additional JS library which provides a fallback. Does CSS-support enable detecting things like support for different font formats and image formats? That's also needed for service workers, but might be a separate API? 99089 1 zcorpan 2014-01-25 20:37:14 +0000 You mean CSS.supports(), right? (In reply to Jonas Sicking from comment #0) > Does CSS-support enable detecting things like support for different font > formats and image formats? No. It just checks if it parses successfully. See http://www.w3.org/TR/css3-conditional/#the-css-interface > That's also needed for service workers, but might > be a separate API? Could you file a new bug for that, please? 99175 2 jonas 2014-01-27 18:57:01 +0000 Yes, I mean CSS.supports(). A more detailed description of the use-case is available in bug 24387 comment 2. That bug tries to cover querying for hardware metrics. However the use case mentioned there could also require asking about software capabilities like CSS support from the worker. In particular, being able to pre-cache JS-libraries which provide fallback to missing CSS support would be useful.