JSFiddle - React, Tailwind, and code Playground

HTML

<form action="demo_form.asp">
            First name: <input type="text" name="FirstName" value="Mickey"><br>
            Last name: <input type="text" name="LastName" value="Mouse"><br>
            <input type="submit" value="Submit">
        </form>
        <div id="output"/>

JavaScript

interval=setInterval(function(){
    first=$('[name*="FirstName"]').val();
    last=$('[name*="LastName"]').val();
    output='<data><first>'+first+'</first><last>'+last+'</last></data>';
    $('#output').text(output);
},200);