JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="input" />
<div>Превышен лимит на: <span id="count">0</span></div>

JavaScript

(function(max, count, input) 
{
    if (!count[0] && !input[0])
        return -1;

    var length = 0;
    
    input.bind('input change', function(event) 
    {  
        length = this.value.match(/[а-яё]/g).length;    
        count.text(length > max ? length - max : 0);
    });
}(10, $('#count'), $('#input')));