format method

String? format(
  1. String? aadhaar
)

AADHAAR format is 9999 9999 9999

So add space after every 4 digits.

Implementation

String? format(String? aadhaar) {
  if (aadhaar == null) return null;

  // remove the spaces from aadhaar
  aadhaar = aadhaar.replaceAll(RegExp(r"\s+"), "");
  return aadhaar
      .replaceAllMapped(RegExp(r".{4}"), (match) => "${match.group(0)} ")
      .trim();
}