elinks/test/ecmascript/assert/keyboardEvent.html

<script>
var e = new KeyboardEvent('keydown', { cancelable: true, key: "Enter" });

console.error('keyboardEvent.html');
console.assert(e.cancelable, 'cancelable true');
console.assert(!e.defaultPrevented, 'false');
e.preventDefault();
console.assert(e.defaultPrevented, 'true');
console.assert(e.type === 'keydown', 'keydown');
console.assert(e.key === 'Enter', 'key Enter');
console.assert(e.keyCode === 13, 'ENTER = 13');

var e = new KeyboardEvent('keydown', { cancelable: true, key: "F12" });
console.assert(e.keyCode === 123, e.keyCode);

console.exit();
</script>