static String concatAll(List<String> strings) {
  return stringJoinUnchecked(_toJsStringArray(strings), "");
}

static String createFromCharCodes(List<int> charCodes) {
  checkNull(charCodes);
  if (!isJsArray(charCodes)) {
    if (charCodes is !List) throw new IllegalArgumentException(charCodes);
    charCodes = new List.from(charCodes);
  }
  return Primitives.stringFromCharCodes(charCodes);
}

static String join(List<String> strings, String separator) {
  checkNull(strings);
  checkNull(separator);
  if (separator is !String) throw new IllegalArgumentException(separator);
  return stringJoinUnchecked(_toJsStringArray(strings), separator);
}