How can I create a card once I click enter on a textInput

Question

Following is the code I have tried:

function createCard(e) {
  console.log(e);
  var card = CardService.newCardBuilder();
  var section = CardService.newCardSection();
  var res = e['formInput'];
  var request = res['queryString'];
  section.addWidget(CardService.newTextParagraph().setText("old widget"));
  card.addSection(section);
  return card.build();
}

function startCard() {
  var mainCard = CardService.newCardBuilder();
  var inputSection = CardService.newCardSection();

  var textInput = CardService.newTextInput()
    .setFieldName("queryString")
    .setTitle("Text input title")
  .setOnChangeAction(CardService.newAction().setFunctionName('createCard'));

  inputSection.addWidget(textInput);

  mainCard.addSection(inputSection);
  return mainCard.build(); 
}

Using this I am trying to create a card with the content specified in the TextInput filed. Once the user click enter after typing text in the field the createCard function must be called.

The function is being called, able to get the queryString as well but the card doesn't appear.