[whatwg] <picture>, `img set`, and polyfills

Charles Pritchard chuck at jumis.com
Mon May 14 21:43:48 PDT 2012

On May 14, 2012, at 8:29 PM, "Kang-Hao (Kenny) Lu" <kennyluck at csail.mit.edu> wrote:

> (12/05/15 7:17), Mathew Marquis wrote:
>> It’s worth noting that a practical polyfill may not be possible when using `img set`, for reasons detailed at length elsewhere:
>> http://www.alistapart.com/articles/responsive-images-how-they-almost-worked-and-what-we-need/
>> http://www.netmagazine.com/features/state-responsive-images
>> Long story short: attempting to write a polyfill for `img set` leaves us in the exact situation we were in while trying to solve the issue of responsive images strictly on the front-end. We would be saddling users with a redundant download—first for the original src, then for the appropriately-sized source if needed. 
>> Where the new element would be all but ignored by existing browsers, efficient polyfills become possible. In fact, two `picture` polyfills exist today: http://wiki.whatwg.org/wiki/Adaptive_images#Functional_Polyfills
> Sorry but I don't understand why <noscript> as used around <img> by
> these polyfills listed can't be used along <img srcset>.
> If your point is that some Web developers will not cater for NoScript
> users and chose to include <img> in <picture>, I think those authors can
> use <img srcset> without @src too (if I understand correctly).
> Cheers,
> Kenny

I think I saw noscript in picasa galleries. It does seem like the always load aspect of img is leading to these techniques. They're great though for fallback.

I guess we are trying to introduce images without loading them upon setting src.

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