JSFiddle - React, Tailwind, and code Playground

HTML

<select id="dropdownId">
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
  <option value="mercedes">Mercedes</option>
  <option value="audi">Audi</option>
</select>

JavaScript

var prev_val;
$('#dropdownId').focus(function () {
  prev_val = $(this).val();
}).change(function () {
  $(this).blur();
  var success = confirm('Are you sure you want to change the dropdown?');
  if (success) {
    // Proceed as normal.
  } else {
    // Reset the value & stop normal event
    $(this).val(prev_val);
    return false;
  }
});