JSFiddle - React, Tailwind, and code Playground

HTML

<input type='text' />

JavaScript

$('input').keydown(function(e){
    $(this).data('prevVal', $(this).val());   
}).keyup(function(e){
    if(e.keyCode === 8) {//delete
        var ele = $(this); 
        var val = ele.data('prevVal'); 
        var newVal = ele.val(); 
        var removedChar = val.substring(val.length-1);
        alert(removedChar); 
    }
});