Detect retina asset in DOM using javascript

retina_detect

function retina(selector) {
  var element = document.querySelector(selector);
  var images = Array.prototype.slice.apply(element.getElementsByTagName("img"));
  var extension = "_2x";
  if (window.devicePixelRatio === 2) {
    images.forEach(function(img, idx) {
      var src = img.getAttribute('src');
      img.setAttribute('src', src.replace(/(\.jpg|\.png|\.gif)$/, extension + '$&'));
      img.onerror = function(evt) {
        img.setAttribute('src', src);
      };
    });
  };
} 
retina('#element');

orly?