JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id=test maxlength=10></textarea>length = <span id=length>0</span>

JavaScript

$(function () {
    $('#test').keyup(function () {
        var x = $('#test').val();

        var newLines = x.match(/(\r\n|\n|\r)/g);
        var addition = 0;
        if (newLines != null) {
            addition = newLines.length;
        }

        $('#length').html(x.length + addition);
    })
})