Retina-images.js

(function($) {
  if (isRetina) { //check if current device is retina 
      $('img[data-hidpi]').each(function() { // loop through images with data-hidpi attribute
        $(this).attr('src', $(this).attr('data-hidpi')); //replace src attribute value with big image 
      });
  }
})(jQuery);

function isRetina(){
    return ((window.matchMedia && (window.matchMedia('only screen and (min-resolution: 192dpi), only screen and (min-resolution: 2dppx), only screen and (min-resolution: 75.6dpcm)').matches || window.matchMedia('only screen and (-webkit-min-device-pixel-ratio: 2), only screen and (-o-min-device-pixel-ratio: 2/1), only screen and (min--moz-device-pixel-ratio: 2), only screen and (min-device-pixel-ratio: 2)').matches)) || (window.devicePixelRatio && window.devicePixelRatio >= 2)) && /(iPad|iPhone|iPod)/g.test(navigator.userAgent);
}