https://www.sunwave.de/bundles/sunwavetravelenginebooking/js/ag-url-modifier.js

1(function () {
2
3    function getCookie(name) {
4        const value = `; ${document.cookie}`;
5        const parts = value.split(`; ${name}=`);
6        if (parts.length === 2) return parts.pop().split(';').shift();
7    }
8
9    function getLocalStorage(key) {
10        try {
11            return localStorage.getItem(key);
12        } catch (e) {
13            return null;
14        }
15    }
16
17    function setLocalStorage(key, val) {
18        try {
19            localStorage.setItem(key, val);
20        } catch (e) {
21        }
22    }
23
24    const cookieName = 'ag';
25    const currentUrl = new URL(window.location.href);
26
27    let agValue = currentUrl.searchParams.get(cookieName);
28    if (!agValue) {
29        agValue = getCookie(cookieName);
30    }
31    if (!agValue) {
32        agValue = getLocalStorage(cookieName);
33    }
34
35    if (agValue) {
36        if (getLocalStorage(cookieName) !== agValue) {
37            setLocalStorage(cookieName, agValue);
38        }
39
40        if (currentUrl.searchParams.get(cookieName) !== agValue) {
41            currentUrl.searchParams.set(cookieName, agValue);
42            window.history.replaceState(null, '', currentUrl.toString());
43        }
44    }
45})();