Yes, but if you over-validate you also risk losing sales. What to do doesn't seem obvious at all, at least to me. You'd want to do some kind of cost-benefit a

Yes, but if you over-validate you also risk losing sales. What to do doesn't seem obvious at all, at least to me. You'd want to do some kind of cost-benefit analysis Also, wouldn't a phone number in effect be validated for most online credit card purchases? I thought credit card processor often match the phone number you provide to the phone number on record for your account to prevent fraud. Skip the javascript validation, and let the cc processor validate the phone number. ...but I have no idea what I'm talking about, please correct me if I'm wrong.