https://www.iii.ie/Portals/_default/Skins/III/dist/js/programme-tabs.js

1function changeActivePTab(event, tabID) {
2    let element = event.target;
3    // find all links on page
4    while (element.nodeName !== "A") {
5        element = element.parentNode;
6    }
7    //get tab links
8    ulElement = element.parentNode.parentNode;
9    aElements = ulElement.querySelectorAll("li > a");
10    //get tab panes
11    tabContents = document.getElementById("programmestabs").querySelectorAll(".tab-content > div");
12    //set classes, styles and show/hide based on tabID of tab selected 
13    for (let i = 0; i < aElements.length; i++) {
14        aElements[i].classList.remove("border-white");
15        aElements[i].classList.add("border-navy-300");
16        tabContents[i].classList.add("hidden");
17        tabContents[i].classList.remove("block");
18    }
19    element.classList.remove("border-navy-300");
20    element.classList.add("border-white");
21    document.getElementById(tabID).classList.remove("hidden");
22    document.getElementById(tabID).classList.add("block");
23}