JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-3.1.0.js"></script>
<div id="mycount">0</div>
<textarea name="aa" class="myclass"  cols="10" rows="10"></textarea>
<textarea name="ff" class="myclass"  cols="10" rows="10"></textarea>
<textarea name="gg" class="myclass"  cols="10" rows="10"></textarea>

JavaScript

$(document).ready(function()
    {
        $(".myclass").keyup(function()
        {
            var count=0;
            $(".myclass").each(function () {
                count+=this.value.length;
            });
            $('#mycount').html(count);
        });
    });