How to call other value from select option form

i have html like this

<div class="form-group">
                        <label for="">Kode Objek Pajak</label>
                        @csrf
                        <select class="form-control" name="kd_obj" id="kd_obj" required>
                            <option>Pilih</option>
                            @foreach ($kd_obj_pjk as $obj_pjk)
                            <option datauni="{{$obj_pjk->uni}}" value="{{$obj_pjk->kd_obj_pjk}}" required>
                                {{$obj_pjk->kd_obj_pjk}}|
                                {{$obj_pjk->nm_obj_pjk}}</option>
                            @endforeach
                        </select>
                    </div>

i try to take the datauni value with this script in jqeury, and it didnt work, any solution guys? sorry im newbie in laravel

function checkValue() {
        var inputValue = document.getElementById('nbkp3').value;
        var idbill = document.getElementById('idBillPPn');

        var unifikasi = document.getElementById('kd_obj').attr('datauni');
        

        if (parseInt(inputValue) >= 2220000 && !isNotificationShown && unifikasi == '1') {
            Swal.fire({
            title: "Peringatan",
            text: "Masukan ID Billing PPN",
            icon: "warning"
            });
            idbill.style.display = 'block';
            isNotificationShown = true;
        } else if (parseInt(inputValue) < 2220000 && isNotificationShown){
            idbill.style.display = 'none'; 
            isNotificationShown = false;
        }
        
    }