在Google App Script中有没有.join()的替代方法？

function joinArray(array, separator) {
  var result = "";
  for (var i = 0; i < array.length; i++) {
    if (i > 0) {
      result += separator;
    }
    result += array[i];
  }
  return result;
}

function joinArray(array, separator) {
  return array.reduce(function(previousValue, currentValue) {
    if (previousValue === "") {
      return currentValue;
    } else {
      return previousValue + separator + currentValue;
    }
  }, "");
}