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

Mathew Marquis mat at matmarquis.com
Tue May 15 07:41:47 PDT 2012

On May 14, 2012, at 8:29 PM, Kang-Hao (Kenny) Lu 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).

Scott Jehl has just posted a great write-up of some of the challenges associated with working around the `img` tag. https://gist.github.com/2701939

> Cheers,
> Kenny

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