const allowedKeys = new Map([
[37, 'left'],
[38, 'up'],
[39, 'right'],
[40, 'down']
]);
document.addEventListener('keydown', function(e) {
let arrow = allowedKeys.get(e.keyCode);
if (arrow) document.querySelector("#Key").innerHTML +=`<br/>${arrow}`;
e.preventDefault();
return false;
});
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