JSFiddle - React, Tailwind, and code Playground

HTML

<input class='txt' type='text' value=''>

JavaScript

$('.txt').bind({             
     
             keyup:function(){
              
                   var objectEvent=$(this);
                   var ck_input = /^[a-z]+$/;
                   var input = $.trim(objectEvent.val());
                   var validationTest =ck_input.test(input);

              		 if(input!==""){
                       if(!validationTest){
                       			objectEvent.val("");
                            alert("nao aceita");
                       } 
                   }  
             }//Fim keyUp
    });//Fim of $('.txt').bind({