ช่วยผมสร้างแปลงจากภาษา VB เป็นภาษา php หน่อยครับหรือ javascript ก้อได้

$A = ctype_digit(1) + ctype_digit(3) + ctype_digit(5) + ctype_digit(7) + ctype_digit(9) + ctype_digit(11);
if((ctype_digit(2) * 2) > 9)
{
$B =  ctype_digit(2) * 2 - 9;
}
else
{
$B = ctype_digit(2) * 2;
}

Public Shared Function CheckSumDigit(ByVal id As String) As Integer
    '// Check input data length
    If Len(id) <> 3 Then
        Return 0
    End If

    Dim digit(3) As Integer
    Dim z As Integer
    For z = 1 To 3
        digit(z) = id.Substring(z - 1, 1)
    Next

    Dim A, B, C, D, E, F, G, H, I, J As Integer
    A = digit(1) + digit(3) + digit(5) + digit(7) + digit(9) + digit(11)
    B = IIf((digit(2) * 2) > 9, digit(2) * 2 - 9, digit(2) * 2)
    C = IIf((digit(4) * 2) > 9, digit(4) * 2 - 9, digit(4) * 2)
   
    D = A + B + C
    E = H Mod 3
    F = IIf(3 - E = 3, 0, 3 - E)
    Return F
End Function

if(isset($_GET['txtID'])) {
   if(checkdigit($_GET['txtID']))
   echo "CORRECT";
   else
   echo "WRONG";
}

if(isset($_GET['txtID'])) {

   if(checkdigit($_GET['txtID'])){
   echo "CORRECT";
   }else{
   echo "WRONG";}
}