formatCardNumber static method
Implementation
static String formatCardNumber(String input) {
// Remove all non-digit characters
final digitsOnly = input.replaceAll(RegExp(r'\D'), '');
final buffer = StringBuffer();
// Add space after every 4 digits (except at the end)
for (int i = 0; i < digitsOnly.length; i++) {
buffer.write(digitsOnly[i]);
if ((i + 1) % 4 == 0 && i + 1 != digitsOnly.length) {
buffer.write(' ');
}
}
return buffer.toString();
}