JSFiddle - React, Tailwind, and code Playground

HTML

<select id="change_item">
    <option value="1">A</option>
    <option value="2">B</option>
</select>
<div id="spinner" style="display:none;padding:15px;background-color:green;color:white;">I'm a spinner!</div>

JavaScript

$(document).ready(function() {
  $("#change_item").change(function() {
    $("#spinner").show();
    var item_id = $(this).val();
    var url = "/system/" + item_id + "/change_item/";
    alert(item_id);
    $("#spinner").hide();
    //$.post(url, item_id, function(html) {
    //  $("#spinner").hide();
    //  window.location.reload(true);
    //});
  });
});