function fillin(make_model2,fieldvalue) {
if (document.getElementById(make_model2)) {
document.getElementById(make_model2).value = fieldvalue;
}
}
function mod10( c_number ) { // LUHN Formula for validation of credit card numbers.
var ar = new Array( c_number.length );
var i = 0,sum = 0;
for( i = 0; i < c_number.length; ++i ) {
ar[i] = parseInt(c_number.charAt(i));
}
for( i = ar.length -2; i >= 0; i-=2 ) {
ar[i] *= 2;
if( ar[i] > 9 ) ar[i]-=9;
} 
for( i = 0; i < ar.length; ++i ) {
sum += ar[i];
}
return (((sum%10)==0)?true:false);	 	
}
function validateCard(c_number,c_type) {
if (document.c_form.c_type.value == "") {
alert("Please enter the type of card.")
document.getElementById('c_type').style.background='FFCCCC';
document.c_form.c_type.focus()
return false}
if (document.c_form.c_number.value == "") {
alert("Please enter your card number.")
document.getElementById('c_number').style.background='FFCCCC';
document.c_form.c_number.focus()
return false}
var length = c_number.length;
switch( c_type ) {
case 'MC':
if( length != 16 ) {
alert("Please enter a valid MasterCard number.");
document.getElementById('c_number').style.background='FFCCCC';
document.c_form.c_number.focus();
return false;
}
var prefix = parseInt( c_number.substring(0,2));
if( prefix < 51 || prefix > 55) {
alert("Please enter a valid MasterCard Card number.");
document.getElementById('c_number').style.background='FFCCCC';
document.c_form.c_number.focus();
return false;
}
break;
case 'VISA':
if( length != 16 && length != 13 ) {
alert("Please enter a valid Visa Card number.");
document.getElementById('c_number').style.background='FFCCCC';
document.c_form.c_number.focus();
return false;
}
var prefix = parseInt( c_number.substring(0,1));
if( prefix != 4 ) {
alert("Please enter a valid Visa Card number.");
document.getElementById('c_number').style.background='FFCCCC';
document.c_form.c_number.focus();
return false;
}
break;
}
if( !mod10( c_number ) ) {
alert("Sorry! This is not a valid credit card number.");
document.getElementById('c_number').style.background='FFCCCC';
document.c_form.c_number.focus();
return false;
}
if (document.c_form.c_number.value.length < 13) {
alert("Please enter the correct card number.")
document.getElementById('c_number').style.background='FFCCCC';
document.c_form.c_number.focus()
return false}
var digits = "0123456789";
for (var i = 0; i < c_form.c_number.value.length; i++)
{
temp = c_form.c_number.value.substring(i, i+1)
if (digits.indexOf(temp) == -1 )
{
alert("Please enter the correct card format.")
return false}
}
if (document.c_form.c_code.value == "") {
alert("Please enter your security code.")
document.getElementById('c_code').style.background='FFCCCC';
document.c_form.c_code.focus()
return false}
if (document.c_form.c_month.value == "") {
alert("Please enter the expiry month of your card.")
document.getElementById('c_month').style.background='FFCCCC';
document.c_form.c_month.focus()
return false}
if (document.c_form.c_year.value == "") {
alert("Please enter the expiry year of your card.")
document.getElementById('c_year').style.background='FFCCCC';
document.c_form.c_year.focus()
return false}
if (document.c_form.c_name.value == "") {
alert("Please enter the name on your card.")
document.getElementById('c_name').style.background='FFCCCC';
document.c_form.c_name.focus()
return false}
if (document.c_form.c_country.value == "") {
alert("Please select the Country.")
document.getElementById('c_country').style.background='FFCCCC';
document.c_form.c_country.focus()
return false}
if (document.c_form.c_phone.value == "") {
alert("Please enter your contact phone number.")
document.getElementById('c_phone').style.background='FFCCCC';
document.c_form.c_phone.focus()
return false}
if (document.c_form.c_email.value == "") {
alert("Please enter your contact email address.")
document.getElementById('c_email').style.background='FFCCCC';
document.c_form.c_email.focus()
return false}
return true
}
function maestro()
{
if (document.c_form.c_type.value == "MAESTRO" && document.c_form.c_start_month.value == "") {
alert("Please enter the start month.")
document.getElementById('c_start_month').style.background='FFCCCC';
document.c_form.c_start_month.focus()
return false}
if (document.c_form.c_type.value == "MAESTRO" && document.c_form.c_start_year.value == "") {
alert("Please enter the start year.")
document.getElementById('c_start_year').style.background='FFCCCC';
document.c_form.c_start_year.focus()
return false}
return true
}