https://app.protrainings.uk/javascripts/gclid_capture.js

1(function () {
2  try {
3    var params = new URLSearchParams(window.location.search);
4    var gclid = params.get('gclid');
5    if (!gclid) return;
6
7    var host = window.location.hostname;
8    var rootDomain = host.split('.').slice(-2).join('.');
9    var maxAgeSeconds = 60 * 60 * 24 * 90;
10
11    document.cookie =
12      'gclid=' + encodeURIComponent(gclid) +
13      '; max-age=' + maxAgeSeconds +
14      '; path=/' +
15      '; domain=.' + rootDomain +
16      '; SameSite=Lax' +
17      (window.location.protocol === 'https:' ? '; Secure' : '');
18  } catch (e) {
19    // swallow; gclid is best-effort
20  }
21})();