JSFiddle - React, Tailwind, and code Playground

HTML

<form action="/my-url/{{design.id}}" data-baseurl="/my-url/{{design.id}}/" method="get">
    <select name="producttype">
        <option value="lite">Select one of option</option>
        <option value="a">Option a</option>
        <option value="b">Option b</option>
        <option value="c">Option c</option>
    </select>
</form>
<a id="test">check action</a>

JavaScript

$("select[name='producttype']").change(function(){
    var form = $("form");
    var action = form.data("baseurl") + $(this).val();
    form.attr("action", action);
});
$("#test").click(function(e){
   e.preventDefault();
   alert($("form").attr("action"));
});