pixture_reloaded-8.x-3.x-dev/scripts/fontfaceobserver-check.js

// Eliminate FOIT (Flash of Invisible Text) caused by web fonts loading slowly
// using font events with Font Face Observer.
(function ($) {

  "use strict";

  Drupal.behaviors.atFFOI = {
    attach: function () {

      $('html').addClass('fa-loading');

      var fontObserver = new FontFaceObserver('FontAwesome');

      // Because we are loading an icon font we need a unicode code point.
      fontObserver.load('\uf287\uf142\uf0fc').then(function () {
        $('html').removeClass('fa-loading').addClass('fa-loaded');
      }, function() {
        $('html').removeClass('fa-loading').addClass('fa-unavailable');
      });

    }
  };
}(jQuery));