W3C home > Mailing lists > Public > public-respimg@w3.org > October 2013

Re: srcN - Alternative to picture and srcset

From: Marcos Caceres <marcos@marcosc.com>
Date: Tue, 1 Oct 2013 19:30:14 +0100
To: "matmarquis.com" <mat@matmarquis.com>
Cc: Scott Jehl <scottjehl@gmail.com>, "Tab Atkins Jr." <jackalmage@gmail.com>, "public-respimg@w3.org" <public-respimg@w3.org>, Robin Berjon <robin@w3.org>
Message-ID: <0CB08D3EFC7847269910C3196257E144@marcosc.com>



On Friday, September 27, 2013 at 6:15 PM, matmarquis.com wrote:

> [ snip ]
>  
> >  
> > >  
> > > > 3. In non-supporting browsers, the src image always will be http
> > > > prefetched,meaning a polyfill for this syntax may not be able to avoid
> > > > wasteful overhead. Element based approaches like picture can avoid overhead
> > > > through use of noscript wrappers on fallback content. Could srcN be
> > > > polyfilled without waste?
> > >  
> > >  
> > > To an extent. If you avoid use of src entirely and polyfill with
> > > script in downlevel browsers, you'll get good behavior in new
> > > browsers, okay (script-gated) behavior in older browsers running
> > > script, and failure in older browsers without JS.
> > >  
> > > Alternately, a similar strategy to what you described can be used:
> > >  
> > > <img src1="..." src2="...">
> > > <noscript><img src="..."></noscript>
> > >  
> > > This is then similar to the behavior of your proposal - it's good in
> > > up-level browsers running script and down-level browsers not running
> > > script, okay in down-level browsers running script, and bad in
> > > up-level browsers not running script (as both images will be shown).
> > > This last problem could probably be worked around by adding a
> > > src1="0x0_image.png" to the fallback, so the image still shows up in
> > > the page, but doesn't display.
> > >  
> > > ~TJ
> >  
> >  
> > I can dig it up to confirm, but I thought there were existing (popular) browsers that will make a wasteful HTTP request on <img> even if a src attr is omitted? Perhaps someone else can chime in.
>  
> It looks as it if isn’t entirely uncommon, based on http://www.nczonline.net/blog/2010/07/13/empty-string-urls-browser-update/
>  
> I wrote up some of my initial thoughts on potential polyfill patterns at https://etherpad.mozilla.org/polyfilling-srcN — I’d love to get more eyes on it.
Some more discussions going on here:
https://gist.github.com/bjankord/6781503  
Received on Tuesday, 1 October 2013 18:30:46 UTC

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