54898767/enumerate-or-map-through-a-list-with-index-and-value-in-dart

main.dart

// https://gist.github.com/NearHuscarl/86ce74d95798635e14c8b848863b429f

extension ExtendedIterable<E> on Iterable<E> {
  /// Like Iterable<T>.map but callback have index as second argument
  Iterable<T> mapIndexed<T>(T Function(E e, int i) f) {
    var i = 0;
    return map((e) => f(e, i++));
  }

  void forEachIndexed(void Function(E e, int i) f) {
    var i = 0;
    forEach((e) => f(e, i++));
  }
}

void main() {
  final inputs = ['a', 'b', 'c', 'd', 'e', 'f'];
  final results = inputs
    .mapIndexed((e, i) => 'item: $e, index: $i')
    .toList()
    .join('\n');

  print('mapIndexed');
  print(results);

  print('');
  print('forEachIndexed');
  inputs.forEachIndexed((e, i) => print('item: $e, index: $i'));
}