how to checked only one in one row checkbox using javascript

how to checked only one in one row checkbox using javascript

here is my view

<?php $c=0; for($a=0; $a < 5; $a++) { ?>
<table>
<tr class="cbclass">
<td><input type="checkbox" name="cbname" value="1" id="cb" class="cb"></td>
<td><input type="text" name="f_nilai1[]" id="id_tnilai<?php echo $c++; ?>" ></td>

<td><input type="checkbox" name="cbname" value="1" id="cb" class="cb"></td>
<td><input type="text" name="f_nilai2[]" id="id_tnilai<?php echo $c++; ?>" ></td>

<td><input type="checkbox" name="cbname" value="1" id="cb" class="cb"></td>
<td><input type="text" name="f_nilai3[]" id="id_tnilai<?php echo $c++; ?>"></td>

<td><input type="checkbox" name="cbname" value="1" id="cb" class="cb"></td>
<td><input type="text" name="f_nilai4[]" id="id_tnilai<?php echo $c++; ?>"></td>

<td><input type="checkbox" name="cbname" value="1" id="cb" class="cb"></td>
<td><input type="text" name="f_nilai5[]" id="id_tnilai<?php echo $c++; ?>"></td>
</tr>

this is my javascript i have already change value in input text when ckeckbox is clicked, i use it because in insert_batch checkbox not post when null so i use input text to post it, and its running well. next is i want only checked in one row, can anybody help me??

<script type="text/javascript">
$(document).ready(function() 
{
var a = $(".cb").length;                                                                                
  $(".cb").click(function(event)
  {
    for(var i=0; i<a; i++) {
        var check = document.getElementsByName('cbname');
            if(check[i].checked) 
        {
                $("#id_tnilai"+[i]).val(1);
                } else {
                $("#id_tnilai"+[i]).val(0);
                }
        }
                                                                                                                                                                                
   });
});
</script>