[mrweasel]

Why is detecting credit cards even useful?

I know what card I have, you telling me "Yep that's a VISA card" isn't really that helpful. Yes, I might enter the first four digits wrong and see the wrong card icon light up may help me a little, but aren't I just as likely to enter the last 12 digits wrong. In the case of VISA you're pretty much just telling me "Yep, that first one is a 4".

[mattmaroon]

Saving one click can increase conversions, and if you're doing any real volume even a tiny fraction of a percent can more than pay for the time involved in implementing something like that.

As to why it can't be detected and just neither asked nor shown, it's handy to show people where the CVV2 number is, and how many digits, as many people don't understand what it is even after repeated use. You'd be surprised how often I call in a food order with my Amex and have them tell me it's a 3 digit number on the back of the card. Even someone who takes CC numbers all day doesn't know that an Amex's CVV2 is a 4 digit number on the front, so you can't expect average Joe Amex user to know better.

Also it's nice to group the digits properly when I'm typing them in. So it's nice to have a form at least detect it, even for me.

[adnrw]

Funnily enough, the form in the original post validated my credit card number as Amex and then validated a 3-digit CVV number as OK.

[davekt]

Some amex cards have a 3 digit cvv [1].

[1] http://ecommerce.shopify.com/c/shopify-discussion/t/heads-up...

[cpwright]

I find it useful when they have the list of cards they take on there, and one lights up (or they are all lit up and the other 3 choices gray out). The thing that they are suggesting with showing me the text of the card seems pretty bogus to me. I know that I'm entering an AMEX or Discover; but I have no idea if the website actually takes them without having some indication of the choices before I start typing.

[medell]

Wouldn't it save the user one click to select what card they've got?

[thefreeman]

I think the GP is questioning whether that piece of information is even necessary to process the transaction.

[neohaven]

"We can't take American Express".

It's a valid thing to say, and a valid thing for you to detect and notify the user about. You know, before they finish typing everything else they have to type in.

[psychometry]

There's no need for the user to select it. Just collect the numbers and send it off to your payment gateway. If the card type is unsupported, which would be rare for anyone using a standard gateway that supports all major cards, then display an error message.

[Theodores]

In the UK it is quite common to not accept AMEX and other cards such as whatever 'Maestro' is. Therefore you do have to show what you do accept so people know to use a sensible-to-the-retailer card.

[netrus]

Maestro is huge in Germany. Many people do not have CC cards, but every singe adult has an EC / Maestro card. And we are really annoyed when they don't work abroad (though they do work with ATMs worldwide in most cases).

[nly]

Maestro used to be Switch. They were popular at one time for under 18 year olds for some reason. AMEX is really seen as a premium option here in the UK, for travellers and those with rich blood.

[bowyakka]

Maestro is in effect a card network, the under 18 popularity stemmed from having a line of cards that were low transactionality, it was the first issuer in the UK to really give cards to under 18's.

[user24]

There's a check digit, so calculating isValidCC should be trivial.