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@MattWilcox

MattWilcox/gist:89e04beb7843b21c204a

Created July 18, 2014 15:18
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How easy it would be to do Responsive Images in HTML and CSS if https://developer.mozilla.org/en-US/docs/Web/CSS/attr worked.
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gistfile1.html
<!doctype html>
<html>
<head>
<style>
img:after { content: attr(data-small url); }
@media screen and (min-width:400px) {
img:after { content: attr(data-medium url); }
}
@media screen and (min-width:600px) {
img:after { content: attr(data-large url); }
}
</style>
</head>
<body>
<img data-small="small.jpg" data-medium="medium.jpg" data-large="large.jpg" />
</body>
</html>
@MattWilcox
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Alas, the url type is not supported and browsers still haven't decided how :after should work on an img.

@brucelawson
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"Note. This specification does not fully define the interaction of :before and :after with replaced elements (such as IMG in HTML)." http://www.w3.org/TR/2009/CR-CSS2-20090908/generate.html

Also, waiting until the CSS defeats the purpose of pre-loading - which Steve Souders calls "the single biggest performance improvement browsers have ever made" - which happens as soon as the browser sees an img, even before DOM is constructed.

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