function getCookie(name){
var matches = document.cookie.match(new RegExp(
"(?:^|; )" + name.replace(/([\.$?*|{}\(\)\[\]\\\/\+^])/g, '\\$1') + "=([^;]*)"
));
return matches ? decodeURIComponent(matches[1]) : undefined;
}
var cidLong = getCookie('_ga');
var tmp = cidLong.split('.');
var cid = tmp[2] + '.' + tmp[3];
console.log(cid);<!-- Global site tag (gtag.js) - Google Analytics -->
<script async src="https://www.googletagmanager.com/gtag/js?id=ХХХХ"></script>
<script>
window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments);}
gtag('js', new Date());
gtag('config', 'ХХХ');
</script>
<!-- Google Tag Manager -->
<script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
})(window,document,'script','dataLayer','ХХХХ');</script>
<!-- End Google Tag Manager -->
<!-- Google Tag Manager (noscript) -->
<noscript><iframe src="https://www.googletagmanager.com/ns.html?id=ХХХХ"
height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript>
<!-- End Google Tag Manager (noscript) -->
<script>
ga.getAll().forEach( (tracker) => {
var id = tracker.get('clientId'); console.log(id)
})
</script>document.cookie.match(/_ga=(.+?);/)[1].split('.').slice(-2).join(".");1/ надёжнее закрывать пути проникновения, а не лечить последствия
можете продолжить развивать проект https://github.com/antimalware/manul