Loading CDN-hosted jQuery with triple fallbacks in Jade template Engine

loadjquery.jade

mixin loadJQuery(version)
  script(src='https://ajax.googleapis.com/ajax/libs/jquery/#{version}/jquery.min.js')

  - var jQueryFallbacks = [];
  - jQueryFallbacks[0] = 'http://code.jquery.com/jquery-' + version + '.min.js';
  - jQueryFallbacks[1] = 'http://ajax.aspnetcdn.com/ajax/jQuery/jquery-' + version + '.min.js';
  - jQueryFallbacks[2] = 'js/jquery' + (version.charAt(0) === '1'? '1': '') +'.js';
  
  each url in jQueryFallbacks
    script.
      window.jQuery || document.write('<script src=#{url}><\/script>');

//if lt IE 9
  mixin loadJQuery('1.10.1')
//if gte IE 9
  <!-->
  mixin loadJQuery('2.0.2')
  <!--