(function () {
  var root = (typeof exports == 'undefined' ? window : exports);
  var config = {
    // Ensure Content-Type is an image before trying to load @2x image
    // https://github.com/imulus/retinajs/pull/45)
    check_mime_type: true
  };
  root.Retina = Retina;

  function Retina() {}
  Retina.configure = function (options) {
    if (options == null) options = {};
    for (var prop in options) config[prop] = options[prop];
  };
  Retina.init = function (context) {
    if (context == null) context = root;
    var existing_onload = context.onload || new Function;
    context.onload = function () {
      var images = document.getElementsByTagName("img"),
        retinaImages = [],
        i, image;
      for (i = 0; i < images.length; i++) {
        image = images[i];
        retinaImages.push(new RetinaImage(image));
      }
      existing_onload();
    }
  };
  Retina.isRetina = function () {
    var mediaQuery = "(-webkit-min-device-pixel-ratio: 1.5),\
      (min--moz-device-pixel-ratio: 1.5),\
      (-o-min-device-pixel-ratio: 3/2),\
      (min-resolution: 1.5dppx)";
    if (root.devicePixelRatio > 1)
      return true;
    if (root.matchMedia && root.matchMedia(mediaQuery).matches)
      return true;
    return false;
  };
  root.RetinaImagePath = RetinaImagePath;

  function RetinaImagePath(path, at_2x_path) {
    this.path = path;
    if (typeof at_2x_path !== "undefined" && at_2x_path !== null) {
      this.at_2x_path = at_2x_path;
      this.perform_check = false;
    } else {
      this.at_2x_path = path.replace(/\.\w+$/, function (match) {
        return "@2x" + match;
      });
      this.perform_check = true;
    }
  }
  RetinaImagePath.confirmed_paths = [];
  RetinaImagePath.prototype.check_2x_variant = function (callback) {
    var http, that = this;
    if (!this.perform_check && typeof this.at_2x_path !== "undefined" && this.at_2x_path !== null) {
      return callback(true);
    } else if (this.at_2x_path in RetinaImagePath.confirmed_paths) {
      return callback(true);
    } else {
      http = new XMLHttpRequest;
      http.open('HEAD', this.at_2x_path);
      http.onreadystatechange = function () {
        if (http.readyState != 4) {
          return callback(false);
        }
        if (http.status >= 200 && http.status <= 399) {
          if (config.check_mime_type) {
            var type = http.getResponseHeader('Content-Type');
            if (type == null || !type.match(/^image/i)) {
              return callback(false);
            }
          }
          RetinaImagePath.confirmed_paths.push(that.at_2x_path);
          return callback(true);
        } else {
          return callback(false);
        }
      }
      http.send();
    }
  }

  function RetinaImage(el) {
    this.el = el;
    this.path = new RetinaImagePath(this.el.getAttribute('src'), this.el.getAttribute('data-at2x'));
    var that = this;
    this.path.check_2x_variant(function (hasVariant) {
      if (hasVariant) that.swap();
    });
  }
  root.RetinaImage = RetinaImage;
  RetinaImage.prototype.swap = function (path) {
    if (typeof path == 'undefined') path = this.path.at_2x_path;
    var that = this;

    function load() {
      if (!that.el.complete) {
        setTimeout(load, 5);
      } else {
        that.el.setAttribute('width', that.el.offsetWidth);
        that.el.setAttribute('height', that.el.offsetHeight);
        that.el.setAttribute('src', path);
      }
    }
    load();
  }
  if (Retina.isRetina()) {
    Retina.init(root);
  }
})();
@@ -3417,24 +3417,75 @@
 rc', path);%0A
+        that.el.setAttribute('data-retina', true);%0A
       %7D%0A    

Add data-retina attribute for async interfaces