JSFiddle - React, Tailwind, and code Playground

HTML

<div id="keyboard">
    <ul class="row">
        <li class="letter" id="q">Q</li>
        <li class="letter" id="w">W</li>. . .</ul>
</div>

CSS

.red { color:#f00; }

JavaScript

$(document).keypress(function(e){
    
    var which_letter = String.fromCharCode(e.which);
    $('#'+which_letter+'').addClass('red');

});

$(document).keyup(function(){
    $(".letter").removeClass('red');
});