JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="txtboxToFilter"/>

JavaScript

$(document).ready(function() {
    $("#txtboxToFilter").keydown(function(event) {
        // Allow only backspace and delete
     
        if ( event.keyCode == 65 || event.keyCode == 66 || event.keyCode == 67 || event.keyCode == 46 || event.keyCode == 8 ) {
                // let it happen, don't do anything
        }
        else {
                // Ensure that it is a number and stop the keypress
               
                        event.preventDefault();
                    alert("Type only A,B,C");
                   
                 
        }
    });
});