JavaScript to detect the key code number of a key that was pressed on the keyboard

you can use JavaScript to detect the key code number of a key that was pressed on the keyboard. Here is a basic example:

<script>
document.addEventListener('keydown', logKey);

function logKey(e) {
  var keyCodeElement = document.getElementById("keyCode");
  keyCodeElement.textContent = e.keyCode;
}
</script>

<p>Press a key to see its key code:</p>
<p>Key code: <span id="keyCode"></span></p>

In this example, we've added a span element with an id of keyCode to the HTML markup. When a key is pressed, the logKey() function updates the text content of the span element with the key code value using the textContent property.

Note that the keyCode property is deprecated in newer versions of JavaScript, and it is recommended to use the key property instead. However, the keyCode property is still widely supported in current browsers, so it should work for your needs.