JsCreditCardChecker

LuhnAlgorithmMethods.js

#Luhn algorithm

function a(inputNum) {       
	var digit, digits, flag, sum, _i, _len;
	flag = true;
	sum = 0;
	digits = (inputNum + '').split('').reverse();        
	for (_i = 0, _len = digits.length; _i < _len; _i++) {       
		digit = digits[_i];      
		digit = parseInt(digit, 10);          
		if ((flag = !flag)) {                      
			digit *= 2;               
		}
		if (digit > 9) {               
			digit -= 9;                    
		}      
		sum += digit;          
	}    
	return sum % 10 === 0;
};

function b(value) {
  // accept only digits, dashes or spaces
  if (/[^0-9- \s]+/.test(value)) return false;

	// The Luhn Algorithm. It's so pretty.
	var nCheck = 0, nDigit = 0, bEven = false;
	value = value.replace(/\D/g, "");

	for (var n = value.length - 1; n >= 0; n--) {
		var cDigit = value.charAt(n),
		nDigit = parseInt(cDigit, 10);

		if (bEven) {
			if ((nDigit *= 2) > 9) nDigit -= 9;
		}

		nCheck += nDigit;
		bEven = !bEven;
	}

	return (nCheck % 10) == 0;
}