JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<head>
<script type="text/javascript">
var t0 = new Date();
var done = function(){ 
	var t1 = new Date();
  var delta = t1 - t0;
  var isrc = document.getElementById('img').src;
  var port = isrc.substr(isrc.indexOf('net:') + 4, isrc.indexOf('/test') - isrc.indexOf('net:') - 4);
  var result = "Your port " + port + " is ";
  if(delta < 400)
  	result += "open. Thanks for sharing! ;-)";
  else
    result += "closed. You are lucky! Can I try again?";
  alert(result);
}
</script>
</head>
<body onload="done()">
<!-- local.jsfiddle.net is mapped to 127.0.0.1 -->
<img id='img' src='https://local.jsfiddle.net:1234/test.gif'>
</body>
</html>