On Oct 23, at 6:11 PM, Dustin Hoffmann wrote:

On Thu Oct 23 2014 at 5:02:52 PM Yoav Weiss <yoav@yoav.ws> wrote:
OK, since you guys ask so nicely: https://codereview.chromium.org/674923004/

On Thu, Oct 23, 2014 at 11:06 PM, Dustin Hoffmann <dustintheweb@gmail.com> wrote:
I've been curious about this for a long time. John, thanks for asking - and Yoav, thank you for your response.

On Thu Oct 23 2014 at 3:56:23 PM Yoav Weiss <yoav@yoav.ws> wrote:
Yeah, that behavior is (intentionally) not specced, and left to the browser to do as it pleases.
Current Blink behavior where smaller resources are downloaded when larger ones are already in the cache is a bug and should be fixed. Unfortunately, I doubt I can get to that before Chrome 40 branches, so I don't think it'd be released before Chrome 41.

On Thu, Oct 23, 2014 at 10:18 PM, John Holt Ripley <john.holtripley@googlemail.com> wrote:
Hi all,

I'm working with non-art directed images in a responsive layout, and noticing that when shrinking the viewport, both Chrome and Opera are then additionally requesting the smaller image instead of shrinking the already downloaded asset.

Is this the intended behaviour? I couldn't see anything in the spec that determines this behaviour, so is it up to browser vendors to determine how to handle this? (Or the browser itself to look at network speed and make a decision from there?)

I can see the need to request the new asset in art-directed cases (within the Picture element for example), but in a simple srcset and sizes situation is this additional download beneficial? Is the performance implication of rescaling a large image offset by the network request?