Intent to Deprecate and Remove: "on-demand" value for hover/any-hover media queries.
Mustaq Ahmed
Primary eng (and PM) emails
Summary
Remove the support for “hover: on-demand” and “any-hover: on-demand” media queries. The “on-demand” value is satisfied for the pointing devices that, for example, “can't normally hover, but will activate hover on a long press”.
After the proposed change, a pointing device that used to satisfy the “on-demand” value would satisfy the “none” value instead.
Motivation
The “on-demand” value for hover/any-hover media queries has been removed from the spec about a year ago because it doesn’t seem to have a convincing use case.
Spec change: github.com/w3c/csswg-drafts/commit/2078b46218f7462735bb0b5107c9a3e84fb4c4b1
Spec discussion: lists.w3.org/Archives/Public/www-style/2016Feb/0041.html
Compatibility And Interoperability Risk
The risk of breakage is low because of low usage. We manually tested selected existing sites (among the few we found) that contain “hover: on-demand”, and found them working fine with the proposed change. See Usage Information below for details.
The interop risk is also low since mobile Safari doesn’t support “on-demand”, and Firefox doesn’t even support hover/any-hover media queries (bugzilla.mozilla.org/show_bug.cgi?id=1035774). Edge has a bug to remove “on-demand” support (developer.microsoft.com/en-us/microsoft-edge/platform/issues/9308676).
Alternative implementation suggestion for web developers
After the change, web developers should use “hover: none” and “any-hover: none” instead of “hover: on-demand” and “any-hover: on-demand” respectively.
Usage information
UseCounter data: So far we have data available from M57 beta (and dev as well) which shows that ~0.02% page visits parse the “on-demand” CSS value.
HttpArchive data: In the 2015-01-15 dataset, there are ~35 sites matching r"hover:\s*on-demand" (out of 16.7M entries). We manually checked the top ones among those ~35 sites (more precisely, the ones with alexa.com ranking <50k) using a Chromium build that doesn’t support “on-demand”, and found all of them working fine:
docs.google.com/a/chromium.org/spreadsheets/d/1NXWEukLpt2zm8Ocu7-jTLTAONUubzj2AZzbtusi5slY/edit?usp=sharing
OWP launch tracking bug
Entry on the feature dashboard
www.chromestatus.com/feature/4719452646014976
Requesting approval to remove too?
Yes.
Chris Harrelson
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