Show Hong Kong districts when the Country field changes to "Hong Kong".

show_hong_kong_districts.html

  <script type="text/javascript">
  // SalsaStaff 126206: Change the State options to be the Hong Kong districts as needed.
  // @see https://salsasupport.zendesk.com/entries/99164537
  // @see https://en.wikipedia.org/wiki/Districts_of_Hong_Kong
  $(document).ready(function() {
    var country = $('*[name=Country]');
    if (country.length != 0) {
      country.change(function() {
        if (country.val() == 'HK') {
          $('*[name=State]')
            .empty()
            .append($('#hong-kong-districts').children());
        }
      });
    }
  })
  </script>
  <select style="display: none;" id="hong-kong-districts">
    <option value="">Please choose a district</option>
    <option value="Central and Western">Central and Western</option>
    <option value="Eastern">Eastern</option>
    <option value="Islands">Islands</option>
    <option value="Kowloon City">Kowloon City</option>
    <option value="Kwai Tsing">Kwai Tsing</option>
    <option value="Kwun Tong">Kwun Tong</option>
    <option value="North">North</option>
    <option value="Sai Kung">Sai Kung</option>
    <option value="Sha Tin ">Sha Tin </option>
    <option value="Sham Shui Po">Sham Shui Po</option>
    <option value="Southern">Southern</option>
    <option value="Tai Po">Tai Po</option>
    <option value="Tsuen Wan">Tsuen Wan</option>
    <option value="Tuen Mun">Tuen Mun</option>
    <option value="Wan Chai">Wan Chai</option>
    <option value="Wong Tai Sin">Wong Tai Sin</option>
    <option value="Yau Tsim Mong">Yau Tsim Mong</option>
    <option value="Yuen Long">Yuen Long</option>
  </select>