If you primarily care more about responsive images than about lazy loading, the Picturefill polyfill (https://github.com/scottjehl/picturefill https://github.co

If you primarily care more about responsive images than about lazy loading, the Picturefill polyfill (https://github.com/scottjehl/picturefill https://github.com/scottjehl/picturefill) is a great option. It's a strict polyfill of the picture / srcset standards, which already have broad, native browser support: http://caniuse.com/#search=picture|srcset http://caniuse.com/#search=picture|srcset