JSFiddle - React, Tailwind, and code Playground

HTML

<form>
    Name: <input type="text" id="test-0" class="test"/>
</form>

JavaScript

var i = 0;
$(document).ready(function(){
    $('.test').each(function(){
        $(this).data('index', i);
        i++;
    });
    $('#test-0').keyup(function(){
        addInput($(this).data('index'));
    });
});

function addInput(idx){
    var next = idx + 1;
    if($('#test-'+next).length <= 0){
        $('form').append('<br/>Name: <input type="text" id="test-'+next+'" class="test"/>');
        $('#test-'+next).data('index',next);
        $('#test-'+next).keyup(function(){
            addInput($(this).data('index'));
        });
    }
}