使用YepNope/Modernizr加载外部Google Fonts样式表

yepnope({
  test: document.documentElement.clientWidth,
  nope: 'https://fonts.googleapis.com/css?family=Roboto',
  callback: function (url) {
    if (url) {
      var link = document.createElement('link');
      link.rel = 'stylesheet';
      link.href = url;
      document.head.appendChild(link);
    }
  }
});

Modernizr.load({
  test: Modernizr.fontface,
  nope: 'https://fonts.googleapis.com/css?family=Roboto',
  callback: function (url) {
    if (url) {
      var link = document.createElement('link');
      link.rel = 'stylesheet';
      link.href = url;
      document.head.appendChild(link);
    }
  }
});