https://www.cdsb.qld.gov.au/__data/assets/js_file/0014/522203/qgds-inpage-search.js

1document.addEventListener('DOMContentLoaded', () => {
2    var selects = document.getElementsByClassName("select2-search__field");
3    const arr = Array.from(selects);
4    arr.forEach(function(item) {
5        item.addEventListener("keyup", focus);
6        item.addEventListener("keydown", focus);
7        item.addEventListener("focus", focus);
8        item.setAttribute("role", "combobox");
9        item.setAttribute("tabindex", "0");
10    });
11    function focus(event) {
12        var keyCode = event.keyCode;
13        if (keyCode === 38 || keyCode === 40) {
14            document.getElementsByClassName("select2-results__option--highlighted")[0].focus();
15        }
16        if (document.getElementsByClassName("select2-results__options").length > 0) {
17            var items = document.getElementsByClassName("select2-results__option");
18            const itemsArray = Array.from(items);
19            itemsArray.forEach(function(item) {
20                item.setAttribute("tabindex", "-1");
21            });
22        }
23        var choices = document.getElementsByClassName("select2-selection__choice");
24        const choicesArray = Array.from(choices);
25        choicesArray.forEach(function(item) {
26            item.setAttribute("tabindex", "-1");
27        });
28    }
29});