serialize google forms response-object with getFormItems()

getFormItems.gs

function onFormSubmit(e) {
  emailResponse( getFormItems(e.response) )
}

/**
 * Sends out respondent notification emails.
 *
 * @param {FormResponse} response FormResponse 
 */
function updateTriggers() {
  var form = FormApp.getActiveForm();
  var triggers = ScriptApp.getUserTriggers(form);
  var settings = PropertiesService.getDocumentProperties();
  var triggerNeeded = true // change this based on settings in your UI e.g.
  // Create a new trigger if required; delete existing trigger if not needed
  var existingTrigger = null;
  for (var i = 0; i < triggers.length; i++) {
    if (triggers[i].getEventType() == ScriptApp.EventType.ON_FORM_SUBMIT) {
      existingTrigger = triggers[i];
      break;
    }
  }
  if (triggerNeeded && !existingTrigger) {
    var trigger = ScriptApp.newTrigger('onFormSubmit')
        .forForm(form)
        .onFormSubmit()
        .create();
  } else if (!triggerNeeded && existingTrigger) {
    ScriptApp.deleteTrigger(existingTrigger);
  }
}

/**
 * Sends out respondent notification emails.
 *
 * @param {FormResponse} response FormResponse 
 */
function emailResponse(response) {
  var form = FormApp.getActiveForm();
  var respondentEmail = response.getRespondentEmail()
  if (respondentEmail) {
    var template = HtmlService.createTemplateFromFile('email/RespondentNotification');
    template.notice = '';
    template.response = JSON.stringify( 
      getFormItems(response),null,2)
    var message = template.evaluate();
    MailApp.sendEmail(respondentEmail,
        "this is a subject",
        message.getContent(), {
          name: form.getTitle(),
            htmlBody: message.getContent()
        });
  }else console.error("no email found")
}

function getFormItems(response){
  var Form      = FormApp.getActiveForm();
  var values    = {}
  var formItems = Form.getItems()
  var getType   = function(i){
    var types = ['CHECKBOX','CHECKBOX_GRID','DATE','DATETIME','DURATION','GRID','IMAGE','LIST','MULTIPLE_CHOICE','PARAGRAPH_TEXT','SCALE','SECTION_HEADER','TEXT','TIME','PAGE_BREAK']
    var res   = 'UNKNOWN'
    for(var j in types ) 
      if( i.getType() == FormApp.ItemType[types[j]] ) res = types[j]
    return res
  }
  formItems.map( function(i){
    var o = {id: i.getId(), title: i.getTitle() ? i.getTitle() : undefined, type: getType(i),item: i}
    if( response && response.getResponseForItem(i) ) o.response = response.getResponseForItem(i).getResponse()
    values[ i.getTitle ? i.getTitle() : i.getId() ] = o
  })
  return values
}