Открыть Dev Tools, заглянуть в исходники, и там найти
all.js:
var e = Array.prototype.slice.call(document.getElementById("values_list").getElementsByTagName("li"));
e.forEach(function(t) {
t.addEventListener("mouseover", function() {
e.forEach(function(e) {
e.className = e.className.replace(/\bactive\b/, "")
});
var t = this;
t.className += " active",
document.getElementById("user_title").innerHTML = t.getAttribute("data-title"),
document.getElementById("user_value").innerHTML = t.getAttribute("data-value"),
t.getAttribute("data-caps") ? document.getElementById("user_value").style.textTransform = "lowercase" : document.getElementById("user_value").style.textTransform = "capitalize"
})
})