isCreditCard function

bool isCreditCard(String str)

Implementation

bool isCreditCard(String str) {
  final creditCard = RegExp(
      r'(?:4[0-9]{12}(?:[0-9]{3,6})?|5[1-5][0-9]{14}|(222[1-9]|22[3-9][0-9]|2[3-6][0-9]{2}|27[01][0-9]|2720)[0-9]{12}|6(?:011|5[0-9][0-9])[0-9]{12,15}|3[47][0-9]{13}|3(?:0[0-5]|[68][0-9])[0-9]{11}|(?:2131|1800|35\d{3})\d{11}|6[27][0-9]{14})$');
  final sanitized = str.replaceAll(' ', '');

  if (!creditCard.hasMatch(sanitized)) {
    return false;
  }
  var sum = 0;
  String digit;
  var shouldDouble = false;

  for (var i = sanitized.length - 1; i >= 0; i--) {
    digit = sanitized.substring(i, i + 1);
    var tmpNum = int.parse(digit);

    if (shouldDouble == true) {
      tmpNum *= 2;
      if (tmpNum >= 10) {
        sum += (tmpNum % 10) + 1;
      } else {
        sum += tmpNum;
      }
    } else {
      sum += tmpNum;
    }
    shouldDouble = !shouldDouble;
  }

  return sum % 10 == 0;
}