isCreditCard function
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;
}