removeNonDigits function

Implementation

String removeNonDigits(String text) {
  final buffer = StringBuffer();
  for (int i = 0; i < text.length; i++) {
    final char = text[i];
    if (char.contains(RegExp(r'[0-9]'))) {
      buffer.write(char);
    }
  }
  return buffer.toString();
}