Angular Lazy load images with cache detection

ng-lazy-load

app.directive('imgPreload', ['$timeout', function($timeout) {
  return {
    restrict: 'A',
    scope: {
      ngSrc: '@'
    },
    link: function(scope, element, attrs) {
      var loaded = false;
      element.on('load', function() {
        loaded = true;
        element.addClass('in');
      }).on('error', function() {
        //
      });
      $timeout(function() {
        if (!loaded) {
          element.addClass('fade')
        }
      }, 10); // is 10ms to detect the image was in the cache?
    }
  };
}])

works with bootstrap class