non-blocking fonts by caching it.

cache-fonts.js

// to encode a font into Base64 use this tool https://www.npmjs.com/package/font-store
 (function (window, document) {
   'use strict';

   var isModernBrowser = (
       'querySelector' in document &&
       'localStorage' in window &&
       'addEventListener' in window
     ),
     key = 'font',
     fonts = [{
         'name': 'titillium_web',
         'md5': '64a81399f2d31c3a555baea86bceb4d7'
       },
       {
         'name': 'source_sans_pro',
         'md5': '9f7c6e5f1ee953a86d0f1ed92f20c599'
       },
     ],
     cache;

   if (!isModernBrowser) {
     // Sorry, browser is too old!
     return;
   }

   function insertFont(value) {
     var style = document.createElement('style');
     style.innerHTML = value;
     document.head.appendChild(style);
   }

   function storeFonts(font) {
     window.addEventListener('load', function () {
       var request = new XMLHttpRequest(),
         response;

       request.open('GET', '/assets/fonts/fonts.' + font.md5 + '.json', true);
       request.onload = function () {
         if (this.status == 200) {
           try {
             response = JSON.parse(this.response);
             insertFont(response.value);
             window.localStorage.setItem(key + '_' + font.name, this.response);
           } catch (e) {
             // LocalStorage is probably full
           }
         }
       };
       request.send();
     });
   }

   try {

     for (var i = 0; i < fonts.length; i++) {
       cache = JSON.parse(window.localStorage.getItem(key + '_' + fonts[i].name));
       if (cache !== null && cache.md5 === fonts[i].md5) {
         insertFont(cache.value);
       } else {
         // Busting cache when md5 doesn't match
         window.localStorage.removeItem(key + '_' + fonts[i].name);
         storeFonts(fonts[i]);
       }
     }

   } catch (e) {
     // Most likely LocalStorage disabled, so hopeless...
     console.warn(e);
     return;
   }
 })(window, document);

credits to http://crocodillon.com/blog/non-blocking-web-fonts-using-localstorage. i just modified his code to allow multiple fonts.