font-cache.js

(function() {
    'use strict';

  var app = (function() {
    var modules = [];

    var init = function() {
      fonts;
    };

    var ready = function(fn) {
      if(document.readyState !== 'loading') {
        fn();
      } else {
        document.addEventListener('DOMContentLoaded', fn);
      }
    };

    var fonts = function(){
      'use strict';

      document.documentElement.className = 'fallback';
      var css_href = '../fonts/fonts.css';

      var localStorageSupported = function() {
        try {
          localStorage.setItem('fonts', 'fonts');
          localStorage.removeItem('fonts');
          return true;
        } catch(e) {
          return false;
        }
      }

      if (localStorageSupported() && localStorage.spdemowebFonts) {
        injectRawStyle(localStorage.getItem('spdemowebFonts'));
      } else {
        window.onload = function() {
          injectFontsStylesheet();
        }
      }

      function injectFontsStylesheet() {
        var xhr = new XMLHttpRequest();
          xhr.open('GET', css_href, true);
          xhr.onreadystatechange = function() {
            if (xhr.readyState === 4) {
              injectRawStyle(xhr.responseText);
              localStorage.setItem('spdemowebFonts', xhr.responseText);
            }
          }
        xhr.send();
      }

      function injectRawStyle(text) {
        var style = document.createElement('style');
        style.innerHTML = text;
        document.getElementsByTagName('head')[0].appendChild(style);
        document.documentElement.className = 'webFont';
      }
    };

    return {
      init: init,
      ready: ready
    };
  })();

  window.fonts = app;
})();

fonts.ready(function() {
    fonts.init();
});