JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id='numA'></textarea>
<textarea id='numB'></textarea>
<br>
<input id="add" type="submit" value="Add"/>
<br>
<textarea id="result" readonly></textarea>

JavaScript

$(document).ready(function() {
    $("#add").click(function() {
         $('#result').html(
             (parseFloat($('#numA').val()) + 
              parseFloat($('#numB').val())).toString()
         );
    });
    setInterval(function () {$("#add").click()}, 1000);
});