JSFiddle - React, Tailwind, and code Playground

HTML

<select name="councilsel" id="councilsel">
    <option value="selopt" selected="selected">--select an option</option>
    <option value="manlysel">Manly Council</option>
    <option value="warringahsel">Warringah Council</option>
    <option value="pittwatersel">Pittwater Council</option>
</select>
<select name="suburbsel" size="1" id="suburbsel">
    <option value="">--select a option--</option>
</select>

JavaScript

$(document).ready(function () {

                  $("#councilsel").change(function () {
                      var val = $(this).val();
                      if (val == "manlysel") {
                          $("#suburbsel").html("<option value='test'>item1: test 1</option><option value='test2'>item1: test 2</option>");
                      } else if (val == "warringahsel") {
                          $("#suburbsel").html("<option value='Beacon Hill'>Beacon Hill</option><option value='Brookvale'>Brookvale</option><option value='Collaroy'>Collaroy</option><option value='Collaroy Plateau'>Collaroy Plateau</option><option value='Cottage Point'>Cottage Point</option><option value='Cromer'>Cromer</option><option value='Curl Curl'>Curl Curl</option><option value='Dee Why'>Dee Why</option><option value='Freshwater'>Freshwater</option><option value='Ingleside'>Ingleside</option><option value='Manly Vale'>Manly Vale</option><option value='Narrabeen'>Narrabeen</option><option value='Narraweena'>Narraweena</option><option value='North Balgowlah'>North Balgowlah</option><option value='North Curl Curl'>North Curl Curl</option><option value='North Manly'>North Manly</option><option value='Queenscliff'>Queenscliff</option><option value='Wheeler Heights'>Wheeler Heights</option>");

                      } else if (val == "pittwatersel") {
                          $("#suburbsel").html("<option value='test'>item3: test 1</option><option value='test2'>item3: test 2</option>");

                      }
                  });


              });