var index = 0;

const label = "XOY";

const display = document.getElementsByClassName("display")[0];

function iterate_characters() {
    display.style.transform = (display.style.transform == "scale(2)") ? "scale(1)" : "scale(2)";
    display.innerHTML = label.charAt(index);
    index = (index == label.length - 1) ? 0 : index + 1;
}

iterate_characters();

setInterval(iterate_characters, 1000);