validateExpirationDate function

String? validateExpirationDate(
  1. String? value
)

Validates an Expiration Date (MM/YY). Returns null if valid, or an error message string if invalid.

Implementation

String? validateExpirationDate(String? value) {
  if (value == null || value.isEmpty) {
    return 'Please enter an expiration date';
  }
  if (!RegExp(r'^(0[1-9]|1[0-2])\/?([0-9]{2})$').hasMatch(value)) {
    return 'Enter a valid expiration date (MM/YY)';
  }
  return null;
}