Hello again everyone.

I have a little problem with a piece of code. After having essentially declared my latest project as finished I started working on something different. After a month, my supervisor wanted to take my project out of the sandbox into "production". Then she notified me that the dropdown filter menu isn't working. It shows "no entries" when a filter is selected.

I had borrowed the code for the dropdown menu from somewhere on this forum and modified it slightly for my needs. After that I added the ability to preselect an entry from the dropdown menu if a GET paramter is passed. (I was supposed to create another website that links to the one in question with a GET paramter, according to which the table must be filtered. And it has to be a selection from the dropdown menu due to the nature of the data. Otherwise I would have just put the GET parameter in the search field)

This is the code in question:

$(document).ready(function () {
    var currentURL = window.location.href;
    var servername = null;
    if (currentURL.includes("?")) {
        servername = currentURL.split("?")[1].split("=")[1];
    }
    $("#table").DataTable({
        initComplete: function () {
            this.api()
                .columns([0, 1])
                .every(function () {
                    var column = this;
                    var select = null;
                    if (column[0][0] == 0) {
                        select = $(
                            '<select id="servermenu"><option value="">Alle Server</option></select>'
                        );
                    } else if (column[0][0] == 1) {
                        select = $(
                            '<select><option value="">Alle Software</option></select>'
                        );
                    }
                    select
                        .appendTo($(column.header()).empty())
                        .on("change", function () {
                            var val = $.fn.dataTable.util.escapeRegex(
                                $(this).val()
                            );
                            column
                                .search(val ? "^" + val + "$" : "", true, false)
                                .draw();
                        });

                    column
                        .data()
                        .unique()
                        .sort()
                        .each(function (d, j) {
                            select.append(
                                '<option value="' + d + '">' + d + "</option>"
                            );
                        });
                });
            if (servername != null) {
                var select = document.getElementById("servermenu");
                select.value = servername;
                column = this.api()
                    .column(0)
                    .search(
                        servername ? "^" + servername + "$" : "",
                        true,
                        false
                    )
                    .draw();
            }
        },

What's driving me really crazy is that this exact code used to work 100% correctly, and after having written and tested it I didn't change a single character of code in the entire project, let alone this file. I have been trying to debug for 1,5 days now. Any help, tips, or pointers are appreciated.

Thanks a lot.