Allow only Persian (Arabic) characters in TextBox using JavaScript

hi

I used below code to prevent insert some character into database

 <script type="text/javascript">
     var specialKeys = new Array();
     specialKeys.push(8); //Backspace
     specialKeys.push(9); //Tab
     specialKeys.push(46); //Delete
     specialKeys.push(36); //Home
     specialKeys.push(35); //End
     specialKeys.push(37); //Left
     specialKeys.push(39); //Right
     function IsAlphaNumeric(e) {
         var keyCode = e.keyCode == 0 ? e.charCode : e.keyCode;
         var ret = ((keyCode >= 48 && keyCode <= 57) || (keyCode >= 65 && keyCode <= 90) || (keyCode >= 97 && keyCode <= 122) || (specialKeys.indexOf(e.keyCode) != -1 && e.charCode != e.keyCode));
         document.getElementById("error").style.display = ret ? "none" : "inline";
         return ret;
     }
    </script>

but I can't enter persian character into database How I can change above code untill I can enter persian character into database?

persian ascii code are:

&#1570 آ
&#1575 ا
&#1576 ب
&#1662 پ
&#1578 ت
&#1579 ث
&#1580 ج
&#1670 چ
&#1581 ح
&#1582 خ
&#1583 د
&#1584 ذ
&#1585 ر
&#1586 ز
&#1688 ژ
&#1587 س
&#1588 ش
&#1589 ص
&#1590 ض
&#1591 ط
&#1592 ظ
&#1593 ع
&#1594 غ
&#1601 ف
&#1602 ق
&#1705 ک
&#1711 گ
&#1604 ل
&#1605 م
&#1606 ن
&#1608 و
&#1607 ه
&#1740 ی
&#1574 ئ
&#1632 0
&#1633 1
&#1634 2
&#1635 3
&#1636 4
&#1637 5
&#1638 6
&#1639 7
&#1640 8
&#1641 9

Best Regards 

Neda