file.html

<HTML>
  <Body>
    <script language="javascript">
      var GET = {};
      var query = window.location.search.substring(1).split("&");
      for (var i = 0, max = query.length; i < max; i++) {
        if (query[i] === "") // check for trailing & with no param
          continue;
        var param = query[i].split("=");
        GET[decodeURIComponent(param[0])] = decodeURIComponent(param[1] || "");
      } //use GET.file
      function populatePre(url) {
        var xhr = new XMLHttpRequest();
        xhr.onload = function () {
            document.getElementById('content').textContent = this.responseText;
        };
        xhr.open('GET', url);
        xhr.send();
      }
      populatePre(GET.file);
    </script>
    <bootmark id="content"></bootmark>
    <script src="https://unpkg.com/bootmark@latest/dist/bootmark.bundle.min.js"></script>
    <script>
      $.fn.bootmark.options.html = {
        theme: 'cyborg',
        toc: false
      };
    </script>
  </Body>
</HTML>