I can call list.add() which adds at the end but there is no convenient way to add an entry to a specific index which at the same time grows the list.
Dart 2
var idx = 3;
list.insert(idx, 'foo');
Depends on whether you want to insert a single item or a bunch of items
All available methods https://api.dartlang.org/stable/2.1.0/dart-core/List-class.html#instance-methods