将php变量作为php中的数组发送到js文件，然后回显每个变量

我有一个表，每行都有按钮显示基于数据行用户点击（使用数据表）的更多详细数据，过程是我使用ajax将数据从js文件传递到php文件然后在那个php文件之后的一些进程生成一个数组再将它返回到js然后按1回显数组1 ..

我成功使用datatablescript.js中的ajax将变量传递给childdatatatable.php .

但我仍然无法想象如何将我从childdatatatable.php生成的数组传回datatablescript.js并显示它（通过alert或echo或任何东西）

sry for bad english ..

这是代码：

transactions.php

<table id="transactiontable" class="table table-striped table-bordered display" cellspacing="0" width="99%">
   <thead>
      <tr>
         <th width="4%"></th>
         <th width="4%">Order Date</th>
         <th width="10%">ID Transaksi</th>
         <th width="7%">User ID</th>
         <th width="9%">Total</th>
         <th width="5%">Status</th>
      </tr>
   </thead>
   <tbody>
      <?php
         $query = mysqli_query($koneksi, "select * from penjualan order by tanggal desc");
         while($data = mysqli_fetch_array($query)){
         ?>
      <tr data-child-value="<?php echo $data['no_pen'];?>" id="<?=($data['no_pen'])?>">
         <td class="details-control"></td>
         <td>
            <center><?php echo $data['tanggal']; ?></center>
         </td>
         <td>
            <center><?php echo $data['no_pen']; ?></center>
         </td>
         <td>
            <center><?php echo $data['id_usr']; ?></center>
         </td>
         <td>
            <center>Rp. <?php echo number_format($data['jumlah_total'],0,'','.'); ?>,-</center>
         </td>
         <td>
            <center><?php echo $data['status']; ?></center>
         </td>
      </tr>
      <?php } ?>
   </tbody>
</table>

datatablescript.js

function format(value) {
    var id = value;
    return '<div>Detail Item : ' + value + '</div>';


}

$(document).ready(function() {
    var table = $('#transactiontable').DataTable({});

    // Add event listener for opening and closing details
    $('#transactiontable').on('click', 'td.details-control', function() {

        var elem = $(this),
            selecteditem = elem.val(),
            id = elem.closest('tr').attr('id');

        $.ajax({
            type: "post",
            url: "childdatatable.php",
            data: {
                'id': id
            },
            success: function(data) {
                if (data) {
                    var test = '<?php echo json_encode($brid) ?>';
                    alert(test);

                }

            }
        });
        var tr = $(this).closest('tr');
        var row = table.row(tr);

        if (row.child.isShown()) {
            // This row is already open - close it
            row.child.hide();
            tr.removeClass('shown');
        } else {
            // Open this row
            row.child(format(tr.data('child-value'))).show();
            tr.addClass('shown');
        }
    });
});

childdatatatable.php

require_once("koneksi.php");
session_start();

    if (!isset($_SESSION['username'])){
        echo "<script>alert('You must register an account first, we will redirect you to register page !'); window.location = 'registuser.php'</script>";
    }

$no_pen = $_POST['id']; 
$query = "SELECT br_id from item_penjualan where penjualan_id = '$no_pen'";

if ($stmt = mysqli_prepare($koneksi,$query))
    {
        mysqli_stmt_execute($stmt);
        mysqli_stmt_bind_result($stmt,$brid);

        while (mysqli_stmt_fetch($stmt)){
            printf ($brid);
        }
        json_encode($brid);
        mysqli_stmt_close($stmt);
    }