google apps script code to combine the calendarapp with an onsubmit trigger in a google form

Code.gs

function cartSignup(event) {

  //this should be the calendar id you get from the settings page
  var CALENDAR_ID = '<<YOUR CALENDAR ID>>';
  
  var responses = event.response.getItemResponses();
  
  var cartResponses = [];
  
  //loop through the item responses and push them into the empty array
  for(var i = 0; i < responses.length; i++) {
    cartResponses.push(responses[i].getResponse());
  }
  
  //concatenate some of the information into a string we will use as the title
  var title = 'Room: ' + cartResponses[0] + ' - ' + cartResponses[3];
  
  //another loop to create each entry based on how many class periods are selected
  for(var j = 0; j < cartResponses[2].length; j++) {
    var classTime = getPeriodTimes(cartResponses[2][j], cartResponses[1]);
    
    CalendarApp.getCalendarById(CALENDAR_ID).createEvent(title, classTime.start, classTime.end);
  }
}

/**
 * Function to return a date object
 */
function getDateObj(date) {
  date = date.split('-');
  
  var year = date[0];
  
  var month = date[1] - 1;
  
  var day = date[2];
  
  date = new Date(year, month, day);
  
  return date;
}

/**
 * Function to set the times for the class periods
 */
function getPeriodTimes(period, day) {
  var start = getDateObj(day);
  var end = getDateObj(day);
  
  switch(period) {
    case 'Period A':
      start.setHours(9);
      end.setHours(10);
      break;
    
    case 'Period B':
      start.setHours(10);
      end.setHours(11);
      break;
    
    case 'Period C':
      start.setHours(11);
      end.setHours(12);
      break;
    
    case 'Period D':
      start.setHours(12);
      end.setHours(13);
      break;
    
    default: break;
  }
  
  return { start: start, end: end };
}