JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://www.skymachine.com/ext/js/globalize-master/lib/globalize.js"></script>
<script src="http://www.skymachine.com/ext/js/globalize-master/lib/cultures/globalize.culture.es-ES.js"></script>
<body>
    <form>Escriba el primer número:
        <input type="text" id="txtNumber1">
    </form>
    <form>Escriba el segundo número:
        <input type="text" id="txtNumber2">
    </form>
    <button id="btnSumar" onclick="Sumar()">¡Sumar!</button>
    <p id="p"></p>
    <script>
        function Sumar() {
            var num1 = Globalize.parseFloat(document.getElementById("txtNumber1").value);
            var num2 = Globalize.parseFloat(document.getElementById("txtNumber2").value);
            resultado = num1 + num2;
            document.getElementById("p").innerHTML = "The result is " + resultado.toLocaleString("de-de");

        }
    </script>
<body>

CSS

body{
   line-height:2;
}

JavaScript

$(document).ready(function () {
    Globalize.culture("de-de");
    console.log(Globalize);
    // note in jsfiddle I had to manually add the es_ES js from the cultures directory.
});