vlas-ilya · October 9, 2015 15:22
diff --git a/isValidCreditCard b/isValidCreditCard
 var isValidCreditCard = function (xs) {
  return xs.split('').reverse().map(function (elem, index, xs) {
      return index % 2 ? (2 * elem < 9 ? 2 * elem : 2 * elem - 9) : Number(elem);
    }).reduce(function(sum, elem) { return sum + elem }) % 10 == 0;
 }
	var isValidCreditCard = function (xs) {
	return xs.split('').reverse().map(function (elem, index, xs) {
	return index % 2 ? (2 * elem < 9 ? 2 * elem : 2 * elem - 9) : Number(elem);
	}).reduce(function(sum, elem) { return sum + elem }) % 10 == 0;
	}