jellyfin-web/dashboard-ui/scripts/extensions.js

function getWindowLocationSearch(win) {

    var search = (win || window).location.search;

    if (!search) {

        var index = window.location.href.indexOf('?');
        if (index != -1) {
            search = window.location.href.substring(index);
        }
    }

    return search || '';
}

function getParameterByName(name, url) {
    name = name.replace(/[\[]/, "\\\[").replace(/[\]]/, "\\\]");
    var regexS = "[\\?&]" + name + "=([^&#]*)";
    var regex = new RegExp(regexS, "i");

    var results = regex.exec(url || getWindowLocationSearch());
    if (results == null)
        return "";
    else
        return decodeURIComponent(results[1].replace(/\+/g, " "));
}

function replaceQueryString(url, param, value) {
    var re = new RegExp("([?|&])" + param + "=.*?(&|$)", "i");
    if (url.match(re))
        return url.replace(re, '$1' + param + "=" + value + '$2');
    else if (value) {

        if (url.indexOf('?') == -1) {
            return url + '?' + param + "=" + value;
        }

        return url + '&' + param + "=" + value;
    }

    return url;
}