Picturefill – a responsive image polyfill

“The picture element, srcset and sizes attributes, and associated features allow web developers to deliver an appropriate image to every user depending on a variety of conditions like screen size, viewport size, screen resolution, and more. Picturefill enables support for the picture element and associated features in browsers that do not yet support them, so you can start using them today!”

<img srcset="examples/images/large.jpg 1x, examples/images/extralarge.jpg 2x" alt="…">

<img
  sizes="(min-width: 40em) 80vw, 100vw"

  srcset="examples/images/medium.jpg 375w,

          examples/images/large.jpg 480w,
          examples/images/extralarge.jpg 768w"
  alt="…">

Picturefill @ Github