function doPost(e) {
  var data = JSON.parse(e.postData.getDataAsString());

  for ( var idx in data["text"] ) {
    data["text"][idx] = LanguageApp.translate(data["text"][idx], data["source"], data["target"]);
    Utilities.sleep(20);
  }

  var response = ContentService.createTextOutput();
  response.setMimeType(ContentService.MimeType.JSON);
  response.setContent(JSON.stringify(data));

  return response;
}