void fillRange(String path, int start, int end, [fillValue])

Sets the objects in the range start inclusive to end exclusive to the given fillValue on the list at path.

Source

void fillRange(String path, int start, int end, [fillValue]) {
  var numToFill = end - start;
  jsElement.callMethod(
      'splice',
      [path, start, numToFill]
        ..addAll(new List.filled(numToFill, convertToJs(fillValue))));
}