contrib/index.html

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

<head>
	<meta charset="utf-8">
	<title>💾🎉 redirect</title>
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<style>

html, body {
	font-family: sans-serif;
}
body {
	padding: 1em 2em;
	font-size: 1.5em;
}
a {
	font-size: 1.2em;
	padding: .1em;
}

</style>
</head>
<body>
	<span id="desc">you probably want</span> <a id="redir" href="//10.13.1.1:3923/">copyparty</a>
	<script>

var a = document.getElementById('redir'),
	proto = location.protocol.indexOf('https') === 0 ? 'https' : 'http',
	loc = location.hostname || '127.0.0.1',
	port = a.getAttribute('href').split(':').pop().split('/')[0],
	url = proto + '://' + loc + ':' + port + '/';

a.setAttribute('href', url);
document.getElementById('desc').innerHTML = 'redirecting to';

setTimeout(function() {
	location.href = url;
}, 500);

</script>
</body>
</html>