https://harald.ist.org/paste/validator.html
1<!DOCTYPE html><html lang="en" tabindex="0"><head><meta charset="UTF-8"></head><body><a id="validator_link" href="https://validator.w3.org/check/referer" accesskey="m">Validate</a>
2<script>
3addEventListener( 'load', ()=>{
4 const uri_encoded = encodeURI( window.location );
5 const validator_uri = 'https://validator.w3.org/check?uri=' + uri_encoded;
6 const link = document.querySelector( '#validator_link' );
7
8 link.href += uri_encoded;
9
10link.href = 'https://validator.w3.org/check' + '/referer';
11
12
13 //const new_link = document.createElement( 'a' );
14 ////new_link.setAttribute( 'style', 'display:none !important;' );
15 //new_link.setAttribute( 'style', 'color:red' );
16 //new_link.setAttribute( 'href', validator_uri );
17 //new_link.setAttribute( 'accesskey'
18 //new_link.textContent = validator_uri;
19 //document.body.appendChild( new_link );
20});
21</script>
22</body></html>

Every program ends, but not all of them halt.