#iframe

<iframe id="raceResultFrame" src="https://my.raceresult.com/324770/registration/" width="100%" height="800" frameborder="0"></iframe>
<script type="text/javascript">
  window.addEventListener('load', function() {
    var iframe = document.getElementById('raceResultFrame');
    setInterval(function() {
      try {
        var newHeight = iframe.contentWindow.document.body.scrollHeight;
        if (newHeight > 300) {
          iframe.style.height = (newHeight + 50) + 'px';
        }
      } catch(e) {
        console.log("error");
      }
    }, 2000);
  });
</script>