$(document).ready(function () {
  'use strict';

  if ($('#new_state_link').length) {
    $('#country').on('change', function () {
      var new_state_link_href = $('#new_state_link').prop('href');
      var selected_country_id = $('#country option:selected').prop('value');
      var new_link = new_state_link_href.replace(/countries\/(\d+)/,
        'countries/' + selected_country_id);
      $('#new_state_link').attr('href', new_link);
    });
  };
});