Associative array decoding in JSON
$setClassResult = array();
 while($row = mysql_fetch_array( $result ))
 {
 $setClassResult= array_push_assoc($setClassResult, $row['item_id'], $row['parent']);
 }
 echo json_encode(array($setClassResult));
 break;

[{"830":"0","734":"830","733":"830","732":"830","735":"830","737":"830","736":"830","738":"830","739":"830","740":"830","741":"830","742":"830","872":"0","869":"872","868":"872","880":"872","964":"872"}]

$.each(data, function(key, val) {
        $("#recordsArray_"+key).toggleClass(val);
        alert(key+" "+val);
  });

echo json_encode($setClassResult);

[{"830":"0","734":"830","733":"830","732":"830","735":"830","737":"830","736":"830","738":"830","739":"830","740":"830","741":"830","742":"830","872":"0","869":"872","868":"872","880":"872","964":"872"}]