https://infostart.ru/bitrix/js/add_cookie.js?v=1.0

1// Ñîäåðæèò ëè URL òåêóùèé äîìåí è get ïàðàìåòð action=buy
2// Äîáàâëåíèå â êîðçèíó
3function checkLinkActionBuy(url) {
4	var currentURL = new URL(url);
5	var currentDomain = window.location.hostname;
6	var actionParam = 'action=buy';
7	
8	// Ïðîâåðÿåì, ñîäåðæèò ëè URL òåêóùèé äîìåí
9	// Ïðè òåñòàõ îòêëþ÷àéòå
10	if (currentURL.hostname === currentDomain) {
11		
12		// Ïðîâåðÿåì, ñîäåðæèò ëè URL ïàðàìåòð action=buy
13		if (url.indexOf(actionParam) !== -1) {
14			//console.log(url);
15			return true;
16		}
17	}
18
19	return false;
20}
21
22
23function addRefererAndCurrentUrl(event) {
24	var expires = "";
25	var days = 365;
26	var date = new Date();
27	date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000)); // â ìèëëèñåêóíäàõ
28	expires = "; expires=" + date.toUTCString();
29	// Äîáàâèì 2 êóêè: òåêóùàÿ è ïðåäûäóùàÿ ñòðàíèöà
30	document.cookie = 'referer=' + document.referrer + expires + '; path=/';
31	document.cookie = 'current_url=' + window.location.href + expires + '; path=/';
32}
33
34function observeDOMChangesAddBasket() {
35	var observer = new MutationObserver(function(mutationsList) {
36		for (var mutation of mutationsList) {
37			for (var addedNode of mutation.addedNodes) {
38				if (
39					addedNode.nodeType === Node.ELEMENT_NODE &&
40					((addedNode.tagName === 'A' && addedNode.href && checkLinkActionBuy(addedNode.href)) || 
41					 addedNode.dataset.action === 'ADD_ALL_TO_CART' ||
42					 addedNode.classList.contains('btn-feedback') ||
43					 addedNode.classList.contains('add-to-marketplace-request-demo') ||
44					 addedNode.classList.contains('btn-callback'))
45				) {
46					// îáðàáîò÷èê ñîáûòèÿ íàæàòèÿ íà ññûëêó èëè ýëåìåíò ôîðìû
47					addedNode.addEventListener('click', addRefererAndCurrentUrl);
48				}
49			}
50		}
51	});
52
53	// Íàñòðàèâàåì íàáëþäàòåëü çà èçìåíåíèÿìè â DOM-äåðåâå
54	observer.observe(document.documentElement, { childList: true, subtree: true });
55}
56
57observeDOMChangesAddBasket();