如何在document.getElementById中创建数组

AS title, I want to create array in document.getElementById because my id is come from repeat region. Below is my javascript and html.

<script type ="text/javascript">
  $(document).ready(function(){
      
      $('table tbody tr').click(function(){
          
          var PurchaserID = window.opener.document.getElementById("PurchaserID");
          var n = 5;
            PurchaserID.value = document.getElementById("test[n]").innerText;
          alert(PurchaserID.value);
          
           window.close();
        
      });
  });
</script>

  <?php do { ?>
      <tr>
      <td id = "test[<?php echo $row_Purchaser['ID'];?>]"  align="center" ><?php echo $row_Purchaser['ID'];?></td>
      <td align="center"><?php echo $row_Purchaser['Name']; ?></td>
      <td align="center"><?php echo $row_Purchaser['IC']; ?></td>
      <td align="center"><?php echo $row_Purchaser['Handphone']; ?></td>
       </tr>
   <?php } while ($row_Purchaser = mysql_fetch_assoc($Purchaser)); ?>

Any problem of my program. Why I can't get the value test[n] to test[5] even I create var n =5; May I know how to solve it. Thanks if you could me !!

</div>