script.js

var links = document.querySelectorAll(".itemLinks");
var wrapper = document.querySelector("#wrapper");


var activeLink = 0;


for (var i = 0; i < links.length; i++) {
    var link = links[i];
    link.addEventListener('click', setClickedItem, false);

    
    link.itemID = i;
}


links[activeLink].classList.add("active");

function setClickedItem(e) {
    removeActiveLinks();

    var clickedLink = e.target;
    activeLink = clickedLink.itemID;

    changePosition(clickedLink);
}

function removeActiveLinks() {
    for (var i = 0; i < links.length; i++) {
        links[i].classList.remove("active");
    }
}


function changePosition(link) {
    link.classList.add("active");

    var position = link.getAttribute("data-pos");
    wrapper.style.left = position;
}