<input onkeydown="return /[a-z]/i.test(event.key)" > //allow WHITE space as well <input onkeydown="return /[a-z\s]/i.test(event.key)" >
<input onkeydown="return /[a-z]/i.test(event.key)" > //allow WHITE space as well <input onkeydown="return /[a-z\s]/i.test(event.key)" >