generate a button that says "Click for random font.". when clicked, one of these should appear: Sans Serif, SFUI Display

<button id="btnChange" onclick="changefont()">Click for random font</button>
<script>
function changefont() {
    var x = document.getElementById("btnChange");
    x.innerHTML = Math.floor((Math.random() * 2) + 1);
}
</script>