JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<head>
    <title></title>
    <script type="text/javascript" language="javascript">
        $(document).ready(function(){
            $('input.form-field').change(function() {
                if($('input.form-field').map(function(index, domElement) {
                   if ($(domElement).val() !== "")
                      return domElement;
                }).length < 2) {
                   $("input[type='submit']").attr('disabled','disabled');                
                } else {
                   $("input[type='submit']").removeAttr('disabled');
                }
                });
        });
    </script>
</head>
<body>
    <form name="input" action="html_form_action.aspx" method="post">
        <div>
            Username: <input class="form-field" type="text" name="user">
        </div>
        <div>
            Surname: <input class="form-field" type="text" name="user">        
        </div>
        <input type="submit" value="Submit" disabled='disables'></form>
</body>
</html>