JSFiddle - React, Tailwind, and code Playground

HTML

<script>
function keyDown(event)
{
  var key = event.keyCode;
  if(!((key >= 65 && key <= 90) || key < 48)) event.preventDefault();
//alert("KeydownEvent Fired");
}
function keypress(event)
{
  var key = event.keyCode;
//  if(!((key >= 65 && key <= 90) || key == 8)) event.preventDefault();
//alert("keypress Event Fired");
}
function keyup(event)
{
alert("key up event fired");
}
</script>
<input type="textbox" pattern="[A-Za-z]" placeholder="Keydown" onkeydown="keyDown(event)"/>
<br/>
<input type="textbox" pattern="[A-Za-z]" placeholder="Keypress" onkeypress="keypress(event)"/>
<br/>
<input type="textbox" pattern="[A-Za-z]" placeholder="Keyup" onkeyup="keyup(event)"/>
<br/>