feature: img[srcset] status: use tags: fallback noie kind: html polyfillurls: PictureFill moreurl: https://css-tricks.com/responsive-images-youre-just-changing-resolutions-use-srcset/
srcset attribute for images allows you to specify different resolutions or pixel-density versions of images. Instead of specifying which image to use at each condition (as you might with a media query or with a
<picture> element) the browser decides which is the most appropriate version to use and only makes one request for the image.
If you know what size the image will display at, the optional
sizes attribute helps the browser to decide the most appropriate image before waiting to reflow the entire DOM first. For example,
sizes="100vw" means a full-width image. (Percentage values will not work here, since the browser will have to answer the question "percent of what?", which requires a full DOM reflow.)
All major evergreen browsers now support
srcset. Older browsers will fallback to the image specified in the
src attribute. Alhtough it is not required, a polyfill is available if you want to bring this functionality to older browsers and Internet Explorer.