A while ago I took over editing of a small part of the HTML spec,
involving the <img> element.
That part is now maintained here:
I have in the past few weeks worked on making the spec more closely match
browsers in how <img> loading works (involving "current request" and
This week I have ported over the http://picture.responsiveimages.org/ spec
to HTML, which added the <picture> element, redefined the srcset attribute
on img and added the sizes attribute on img, and also the .currentSrc IDL
attribute on img.
Open issues are currently in two places for historical reasons:
There is ongoing work to implement this in Blink, Gecko, and
WebKit. For IE it is "under consideration".
This work has been baking in the picture specification for some time and
we have worked very closely with implementors for the past few months. I
consider it to be stable. I don't expect any further
backwards-incompatible changes at this point.
Feedback is very much welcome.