BadFL Example Code (extension/num)

main.dart

extension NumExt on num {
  String readableFixed([int fractionDigits = 1]) {
    final absVal = abs();

    String raw = '';
    String unit = '';

    switch (absVal) {
      case < 1e3:
        raw = toStringAsFixed(fractionDigits);
        break;
      case < 1e6:
        raw = (this / 1e3).toStringAsFixed(fractionDigits);
        unit = 'K';
        break;
      case < 1e9:
        raw = (this / 1e6).toStringAsFixed(fractionDigits);
        unit = 'M';
        break;
      default:
        raw = (this / 1e9).toStringAsFixed(fractionDigits);
        unit = 'B';
        break;
    }

    final display = raw.replaceAll(RegExp(r'\.?0+$'), '');
    return '$display$unit';
  }

  String get readable => readableFixed();

  String get segmented {
    String str = toString();
    RegExp regExp = RegExp(r'(\d{1,3})(?=(\d{3})+(?!\d))');
    return str.replaceAllMapped(regExp, (Match match) => '${match[1]},');
  }
}

void main() {
  final List<num> nums = [
    42,
    12345,
    99802,
    9850024,
    10e7,
    10e9 + 500,
  ];

  for (num n in nums) {
    print('number: ${n.readable}');
    print('readable: ${n.readable}');
    print('segmented: ${n.segmented}\n');
  }
}