JSFiddle - React, Tailwind, and code Playground

HTML

<select name="jabatan"  class="selectpicker form-control jabatan_select" data-live-search="true"">
<option value="">Pilih Jabatan</option>
<option value="1">Kuasa Pengguna Anggaran</option>
<option value="2">Pejabat Pembuat Komitmen</option>
<option value="3">Pejabat Pemeriksa Penandatangan SPM</option>
<option value="4">Bendahara Pengeluaran</option>
<option value="5">Bendahara Penerimaan</option>
<option value="6">Bendahara Materiil</option>
</select>

<a id="jabatanID" href="#" data-id="" class="btn btn-warning btn-block assigndata">Click</a>

JavaScript

$(document).ready(function(){
        $("select").change(function(){
            jabatan_id = $(this).val();
            $("#jabatanID").attr("data-id", jabatan_id);
        });
    });
    
 $(document).ready(function () {
        $(".assigndata").click(function () {
            var jabatan_id = $(this).data('id');
            if(jabatan_id == ''){
                alert("choose id");
            }
            else {
                alert(jabatan_id);

            }
        });
    });