test/www/index.html

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="utf-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <!-- The above 3 meta tags *must* come first in the head; any other head content must come *after* these tags -->

  <script>
  // https://davidwalsh.name/get-absolute-url
  var getAbsoluteUrl = (function() {
    var a;

    return function(url) {
      if (!a) a = document.createElement('a');
      a.href = url;
      return a.href;
    };
  })();

  function getCrossDomainUrl(url) {
    var port = Number(/\:(\d+)\//.exec(url)[1]) || 80;
    return url.replace(port, port + 1);
  }

  function addScript(url, parent) {
    var script = document.createElement("script");
    script.type = "text/javascript";
    script.src = url;
    (parent || document.getElementsByTagName("head")[0]).appendChild(script);
  }

  function addCss(url, parent) {
    var link = document.createElement("link");
    link.rel = "stylesheet";
    link.href = url;
    (parent || document.getElementsByTagName("head")[0]).appendChild(link);
  }

  function addCrossDomainScript(selector, timingAllowOrigin) {
    var script = document.querySelector(selector);
    var url = getAbsoluteUrl(script.src);
    if (timingAllowOrigin) {
      url += "?timingAllowOrigin=true";
    }
    addScript(getCrossDomainUrl(url));
  }

  function addCrossDomainCss(selector, timingAllowOrigin) {
    var link = document.querySelector(selector);
    var url = getAbsoluteUrl(link.href);
    if (timingAllowOrigin) {
      url += "?timingAllowOrigin=true";
    }
    addCss(getCrossDomainUrl(url));
  }
  </script>

  <title>Test</title>
  <meta name="description" content="">
  <meta name="author" content="">
  <link rel="icon" href="./favicon.ico">
  <link id="css" href="./assets/css.css" rel="stylesheet">
</head>

<body>

  <span class="glyphicon glyphicon-asterisk"></span>

  <script id="js" src="./assets/js.js"></script>

  <script>
  addCrossDomainScript("#js");
  addCrossDomainScript("#js", true);
  addCrossDomainCss("#css");
  addCrossDomainCss("#css", true);
  </script>

</body>

</html>