javascripts and css fallbacks examples

1-header.html

<!-- Bootstrap CSS CDN -->
    <link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.0.2/css/bootstrap.min.css">

    <!-- HTML5 shim and Respond.js IE8 support of HTML5 elements and media queries -->

      <script src="https://oss.maxcdn.com/libs/html5shiv/3.7.0/html5shiv.js"></script>
      <script>
        // html5shiv local fallback 
        window.html5 || document.write('<script src="vendor/afarkas/html5shiv/dist/html5shiv.js"><\/script>')
      </script>
      <script src="https://oss.maxcdn.com/libs/respond.js/1.3.0/respond.min.js"></script>
      <script>
        // respond.js local fallback 
        window.respond || document.write('<script src="vendor/scottjehl/respond/respond.min.js"><\/script>')
      </script>

2-footer.html

<!-- Bootstrap core JavaScript
    ================================================== -->
    <script src="https://code.jquery.com/jquery-1.10.2.min.js"></script>
    <!-- jQuery local fallback -->
    <script>window.jQuery || document.write('<script src="components/jquery/jquery.min.js"><\/script>')</script>

    <!-- Bootstrap JS CDN -->
    <script src="//netdna.bootstrapcdn.com/bootstrap/3.0.2/js/bootstrap.min.js"></script>
    <!-- Bootstrap JS local fallback -->
    <script>if(typeof($.fn.modal) === 'undefined') {document.write('<script src="components/bootstrap/js/bootstrap.min.js"><\/script>')}</script>

    <!-- Bootstrap CSS local fallback -->
    <script>
      $(document).ready(function() {
      var bodyColor = $('body').css('color');
      if(bodyColor != 'rgb(51, 51, 51)') {
      $("head").prepend('<link rel="stylesheet" href="components/bootstrap/css/bootstrap.min.css">');}});
    </script>