keydown, keyup, keypress

HTML

Press any key and get the message here: <span id="state-msg"></span>

JavaScript

var msg = document.getElementById('state-msg');
document.body.addEventListener('keydown', function(event) {
    const regex = /^[A-Za-z]$/

        // validate key press is alphabetic
        if( regex.test(event.key) ) {
        
            //console.log(event.key);
            msg.textContent = "a-z or A-z  " + event.Key;

         } else {

            //console.log(event.key);
            msg.textContent = "other than a-z or A-z";

        };
});