Using sweet alert confirmation when using condition in behindcode ASP.net

I have made the confirmation but have not used sweet alerts and it is working correctly

this is my code before

<asp:Button ID="btnSaveDetail" CssClass="btn btn-primary col-sm-2" runat="server" Text="Setujui" OnClick="btnSaveDetail_Click" OnClientClick = "Confirm()" />
              
<script type = "text/javascript">
function Confirm() {

    var confirm_value = document.createElement("INPUT");
    confirm_value.type = "hidden";
    confirm_value.name = "confirm_value";
    if (confirm("Apakah Kamu Yakin Menyimpan Data Ini?")) {
        confirm_value.value = "Ya";
    } else {
        confirm_value.value = "Tidak";
    }
    document.forms[0].appendChild(confirm_value);
}

and there is condition when i klik OK in aspx.cs like this

string confirmValue = Request.Form["confirm_value"];
            if (confirmValue == "Ya")
            {
                if (check == 1)
                {
                    DateTime date = DateTime.Now;
                    string date_str = date.ToString("yyyy-MM-dd");
                    lib.CallProcedure("[iu_update_Konfirmpeminjaman]", new string[] { lblID.Text, "5", Session["creaby"].ToString(), date_str, Session["creaby"].ToString(), date_str });
                    loadData();
                }
                else {
                    DateTime date = DateTime.Now;
                    string date_str = date.ToString("yyyy-MM-dd");
                    lib.CallProcedure("[iu_update_Konfirmpeminjaman]", new string[] { lblID.Text, "3", Session["creaby"].ToString(), date_str, Session["creaby"].ToString(), date_str });
                    loadData();
                }
               
            }

But i want to make it with sweet alerts, i tried but still not works, i changed my code like this, can u guys help me how to make it works?

<asp:Button ID="btnSaveDetail" CssClass="btn btn-primary col-sm-2" runat="server" Text="Setujui" OnClick="btnSaveDetail_Click" OnClientClick="return setujuialert(this, event);" />

         <script type="text/javascript">
function setujuialert(ctl, event) {
        var defaultAction = $(ctl).prop("href");
        event.preventDefault();
        swal({
            title: "Penyetujuan",
            text: "Apakah Anda Yakin Ingin Menyetujui Peminjaman ini?",
            type: "warning",
            showCancelButton: true,
            confirmButtonColor: "#DD6B55",
            confirmButtonText: "Ya",
            cancelButtonText: "Tidak",
            closeOnConfirm: false,
            closeOnCancel: false
        },
        function (isConfirm) {
            var confirm_value = document.createElement("INPUT");
            confirm_value.type = "hidden";
            confirm_value.name = "confirm_value";
            if (isConfirm) {
                swal({ title: "Berhasil!", text: "Peminjaman Berhasil Disetujui.", type: "success", confirmButtonText: "OK!", closeOnConfirm: false },
                function () {
                    confirm_value.value = "Ya";
                    return true;
                });
            } else {
                swal("Batal", "Peminjaman Batal Disetujui", "error");
                return false;
            }
        });
    }