Credit Card Validation

I was wondering if credit card validation was done by communication with a card company, or if it could be done with a script. This would be implemented on a secure server, of course. If it can be done with a script, can someone tell me how to get started?

Peter

Best off using a third party when involving credit cards. Use something like www.paysystems.com

This works for me. It will validate whether or not the Credit Card Number is a possible credit card number. There are certain mathmatical rules (which I will not get into now, [because I don't know them]) which determine possible valid numbers.

This has always worked for me.

function isValidCC(n) {
re = /^((4\d{3})|(5[1-5]\d{2})|(6011))-?\d{4}-?\d{4}-?\d{4}|3[4,7]\d{13}$/
return = re.test(n);
}

Usage:
if (isValidCC("1234569878956454")) {
alert("YAY, it is valid");
} else {
alert("Blast, it is invalid!");
}