webfont.js

<script>
  (function(){
    'use strict';

    /**
     * Function to inject Muli
     */
    function addFont(){
      var style = document.creatElement('style');
      style.rel = 'stylesheet';
      style.textContent = localStorage.sourceMuli;
    }

    /**
     * Check localStorage or get the font
     */
    if(localStorage.sourceMuli){
      addFont();
    }else{
      var request = new XMLHttpRequest();
      request.open('GET', 'fonts/muli/stylesheet.css');

      request.onload = function(){
        if(request.status >= 200 || request.status < 400){
          localStorage.sourceMuli = request.responseText;

          addFont();
        }

      request.send();
      };
    }

  }());
</script>