只需一点点的勺子喂养:

$("#CreditCardNumber").focusout(function () {


        var regVisa = /^4[0-9]{12}(?:[0-9]{3})?$/;
        var regMasterCard = /^5[1-5][0-9]{14}$/;
        var regAmex = /^3[47][0-9]{13}$/;
        var regDiscover = /^6(?:011|5[0-9]{2})[0-9]{12}$/;

        if (regVisa.test($(this).val())) {
            $("#CCImage").html("<img height='40px' src='@Url.Content("~/images/visa.png")'>");          

        }

        else if (regMasterCard.test($(this).val())) {
        $("#CCImage").html("<img height='40px' src='@Url.Content("~/images/mastercard.png")'>");

        }

        else if (regAmex.test($(this).val())) {

           $("#CCImage").html("<img height='40px' src='@Url.Content("~/images/amex.png")'>");

        }
         else if (regDiscover.test($(this).val())) {

           $("#CCImage").html("<img height='40px' src='@Url.Content("~/images/discover.png")'>");

        }
        else {
        $("#CCImage").html("NA");

        }

    });

Stripe提供了这个很棒的javascript库来检测卡片方案。让我添加一些代码片段，并向您展示如何使用它。

首先包括它到你的网页作为

<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery.payment/1.2.3/jquery.payment.js " ></script>

其次，利用功能cardType来检测卡片方案。

$(document).ready(function() {              
            var type = $.payment.cardType("4242 4242 4242 4242"); //test card number
            console.log(type);                                   
}); 

这里有更多示例和演示的参考链接。

Stripe博客的jquery.payment.js Github库

压缩javascript版本

    var getCardType = function (number) {
        var cards = {
            visa: /^4[0-9]{12}(?:[0-9]{3})?$/,
            mastercard: /^5[1-5][0-9]{14}$/,
            amex: /^3[47][0-9]{13}$/,
            diners: /^3(?:0[0-5]|[68][0-9])[0-9]{11}$/,
            discover: /^6(?:011|5[0-9]{2})[0-9]{12}$/,
            jcb: /^(?:2131|1800|35\d{3})\d{11}$/
        };
        for (var card in cards) {
            if (cards[card].test(number)) {
                return card;
            }
        }
    };

这里有完整的c#或VB代码，用于各种CC相关的东西。

IsValidNumber GetCardTypeFromNumber GetCardTestNumber PassesLuhnTest

这篇文章已经发布了几年，没有任何负面评论。

在javascript中:

function detectCardType(number) {
    var re = {
        electron: /^(4026|417500|4405|4508|4844|4913|4917)\d+$/,
        maestro: /^(5018|5020|5038|5612|5893|6304|6759|6761|6762|6763|0604|6390)\d+$/,
        dankort: /^(5019)\d+$/,
        interpayment: /^(636)\d+$/,
        unionpay: /^(62|88)\d+$/,
        visa: /^4[0-9]{12}(?:[0-9]{3})?$/,
        mastercard: /^5[1-5][0-9]{14}$/,
        amex: /^3[47][0-9]{13}$/,
        diners: /^3(?:0[0-5]|[68][0-9])[0-9]{11}$/,
        discover: /^6(?:011|5[0-9]{2})[0-9]{12}$/,
        jcb: /^(?:2131|1800|35\d{3})\d{11}$/
    }

    for(var key in re) {
        if(re[key].test(number)) {
            return key
        }
    }
}

单元测试:

describe('CreditCard', function() {
    describe('#detectCardType', function() {

        var cards = {
            '8800000000000000': 'UNIONPAY',

            '4026000000000000': 'ELECTRON',
            '4175000000000000': 'ELECTRON',
            '4405000000000000': 'ELECTRON',
            '4508000000000000': 'ELECTRON',
            '4844000000000000': 'ELECTRON',
            '4913000000000000': 'ELECTRON',
            '4917000000000000': 'ELECTRON',

            '5019000000000000': 'DANKORT',

            '5018000000000000': 'MAESTRO',
            '5020000000000000': 'MAESTRO',
            '5038000000000000': 'MAESTRO',
            '5612000000000000': 'MAESTRO',
            '5893000000000000': 'MAESTRO',
            '6304000000000000': 'MAESTRO',
            '6759000000000000': 'MAESTRO',
            '6761000000000000': 'MAESTRO',
            '6762000000000000': 'MAESTRO',
            '6763000000000000': 'MAESTRO',
            '0604000000000000': 'MAESTRO',
            '6390000000000000': 'MAESTRO',

            '3528000000000000': 'JCB',
            '3589000000000000': 'JCB',
            '3529000000000000': 'JCB',

            '6360000000000000': 'INTERPAYMENT',

            '4916338506082832': 'VISA',
            '4556015886206505': 'VISA',
            '4539048040151731': 'VISA',
            '4024007198964305': 'VISA',
            '4716175187624512': 'VISA',

            '5280934283171080': 'MASTERCARD',
            '5456060454627409': 'MASTERCARD',
            '5331113404316994': 'MASTERCARD',
            '5259474113320034': 'MASTERCARD',
            '5442179619690834': 'MASTERCARD',

            '6011894492395579': 'DISCOVER',
            '6011388644154687': 'DISCOVER',
            '6011880085013612': 'DISCOVER',
            '6011652795433988': 'DISCOVER',
            '6011375973328347': 'DISCOVER',

            '345936346788903': 'AMEX',
            '377669501013152': 'AMEX',
            '373083634595479': 'AMEX',
            '370710819865268': 'AMEX',
            '371095063560404': 'AMEX'
        };

        Object.keys(cards).forEach(function(number) {
            it('should detect card ' + number + ' as ' + cards[number], function() {
                Basket.detectCardType(number).should.equal(cards[number]);
            });
        });
    });
});

试试kotlin。添加Regex并添加到when语句中。

private fun getCardType(number: String): String {

        val visa = Regex("^4[0-9]{12}(?:[0-9]{3})?$")
        val mastercard = Regex("^5[1-5][0-9]{14}$")
        val amx = Regex("^3[47][0-9]{13}$")

        return when {
            visa.matches(number) -> "Visa"
            mastercard.matches(number) -> "Mastercard"
            amx.matches(number) -> "American Express"
            else -> "Unknown"
        }
    }