<!DOCTYPE html>
<html>
<body>
<p>Press the "A" key on the keyboard in the input field to alert some text.</p>
<input type="text" size="40" onkeydown="myFunction(event)">
<p><strong>Note:</strong> The key property is currently only supported in Firefox and IE9+.</p>
<script>
function myFunction(event) {
var x = event.key;
// If the pressed keyboard button is "a" or "A" (using caps lock or shift), alert some text.
if (x == "a" || x == "A") {
alert ("You pressed the 'A' key!");
}
}
</script>
</body>
</html>