hudkit doesn't seem to recognize when buttons are pressed on the keyboard. Here's a simple test page that should be displaying the keycodes.
<html>
<head></head>
<style>
body {
background-color: #000;
font-size: 30px;
font-weight: bold;
color: #fff;
}
</style>
<body>
<p id='keyCode'></p>
<script>
document.addEventListener('keydown', function(e) {
document.getElementById("keyCode").innerHTML = e.keyCode;
});
</script>
</body>
</html>