Class PromptResponse

// Display a dialog box with a title, message, input field, and "Yes" and "No" buttons. The
// user can also close the dialog by clicking the close button in its title bar.
var ui = DocumentApp.getUi();
var response = ui.prompt('Getting to know you', 'May I know your name?', ui.ButtonSet.YES_NO);

// Process the user's response.
if (response.getSelectedButton() == ui.Button.YES) {
  Logger.log('The user\'s name is %s.', response.getResponseText());
} else if (response.getSelectedButton() == ui.Button.NO) {
  Logger.log('The user didn\'t want to provide a name.');
} else {
  Logger.log('The user clicked the close button in the dialog\'s title bar.');
}