JSFiddle - React, Tailwind, and code Playground

HTML

<textarea name="additional_comments" cols="40" rows="4" id="additional_comments"></textarea> 
<input id="finalcount" value="0" disabled />

JavaScript

$(function() {
    var maxWords = 10;
    var wordCounts = {};
    $("#additional_comments").keyup(function() {
        var matches = this.value.match(/\b/g);
        wordCounts[this.id] = matches ? matches.length / 2 : 0;
        var finalCount = 0;
        $.each(wordCounts, function(k, v) {
            finalCount += v;
        });
        $('#finalcount').val('Words: ' + finalCount);
        if(finalCount > maxWords){
            $("#additional_comments").val(a.value.slice(0,-2));
        }
    }).keyup();
});