creditcard.js

// Copyright (c) 2008-2012 Thomas Fuchs
// http://mir.aculo.us/
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

// creditcard.js requires underscore.js
//
// CreditCard.validate('1111 2222 3333 4444') -> true/false
//   the given string is automatically stripped of whitespace, so it can be
//   plugged directly into form validations
//
// The following things are tested:
//   1. does the luhn validation code add up? (see http://en.wikipedia.org/wiki/Luhn_algorithm)
//   2. does the number range and length seem right? (see http://en.wikipedia.org/wiki/Bank_card_number)
//   3. is it one of several well-known test numbers?
//
// Card identification via CreditCard.type(string) -> "Visa", "MasterCard", etc.
// Also, CreditCard.isVisa(string) -> true/false (works for all cards given in CARDS)
//
// Be sure to adapt the CARDS array to the credit cards you accept.

var CreditCard = {
  CARDS: {
    Visa: /^4[0-9]{12}(?:[0-9]{3})?$/,
    MasterCard: /^5[1-5][0-9]{14}$/,
    DinersClub: /^3(?:0[0-5]|[68][0-9])[0-9]{11}$/,
    Amex: /^3[47][0-9]{13}$/,
    Discover: /^6(?:011|5[0-9]{2})[0-9]{12}$/
  },
  TEST_NUMBERS: ('378282246310005 371449635398431 378734493671000 '+
    '30569309025904 38520000023237 6011111111111117 '+
    '6011000990139424 5555555555554444 5105105105105100 '+
    '4111111111111111 4012888888881881 4222222222222'
  ).split(' '),
  validate: function(number){
    return CreditCard.verifyLuhn10(number)
      && !!CreditCard.type(number)
      && !CreditCard.isTestNumber(number)
  },
  verifyLuhn10: function(number){
    return _(CreditCard.strip(number).split('').reverse())
      .reduce(function(a,n,index){
        return a + _((+n * [1,2][index%2]).toString().split(''))
          .reduce(function(b,o){ return b + +o }, 0) 
      }, 0) % 10 == 0
  },
  isTestNumber: function(number){
    return _.include(CreditCard.TEST_NUMBERS, CreditCard.strip(number))
  },
  strip: function(number) {
    return number.replace(/\s/g,'')
  },
  type: function(number) {
    for(var card in CreditCard.CARDS)
      if(CreditCard['is'+card](number)) return card
  }
}

;(function(){
  _.each(CreditCard.CARDS, function(exp, card) {
    CreditCard['is'+card] = _.compose(_.bind(exp.test, exp), CreditCard.strip)
  })
})()