Events are not getting added in calendar - google-apps-script

Question

I have the name for event and end date (without start date) in Google Sheets.
Column B is the name of the event and column C is end date.
The script says execution successful but events are not getting added in Google Calendar.
I am the owner and have full rights/permission.
Here's the script:
function onOpen() {
var ui = SpreadsheetApp.getUi();
var menu = ui.createMenu('Sync to Calendar');
var item = menu.addItem('Commit', 'syncCalendar');
item.addToUi();
}
function calendar() {
var spreadsheet = SpreadsheetApp.getActiveSheet();
var eventCal = CalendarApp.getCalendarById("calendarid**");
var name = spreadsheet.getRange('B3:B250').getValue();
var start = new Date(spreadsheet.getRange('C3:C250').getValue()).getTime();
var end = new Date(spreadsheet.getRange('C3:C250').getValue()).getTime();
eventCal.createEvent(name,new Date(start),new Date(end));
Logger.log('Reminder is added to your calendar');
}

Answer 1

You have to make a loop as follows
const cal = '#################gmail.com'
function calendar() {
var spreadsheet = SpreadsheetApp.getActiveSheet();
var eventCal = CalendarApp.getCalendarById(cal);
var lastRow = spreadsheet.getLastRow()
var name = spreadsheet.getRange('B3:B' + lastRow).getValues().flat();
var start = spreadsheet.getRange('C3:C' + lastRow).getValues().flat();
var end = spreadsheet.getRange('C3:C' + lastRow).getValues().flat();
name.forEach((n, i) => {
try {
var id = eventCal.createEvent(n, new Date(start[i].getTime()), new Date(end[i].getTime())).getId();
console.log(id)
} catch (e) {
console.log(i + ' ' + e)
}
})
Logger.log('Reminder is added to your calendar');
}
flat()
forEach()

Answer 2

With the help of #Mike Steelson this script is working.
However, when you run the code again, it creates duplicates in the calendar.
Is there any way to avoid this?
const cal = 'yourcalendarid#group.calendar.google.com'
function calendar() {
var spreadsheet = SpreadsheetApp.getActiveSheet();
var eventCal = CalendarApp.getCalendarById(cal);
var lastRow = spreadsheet.getLastRow()
var name = spreadsheet.getRange('B3:B' + lastRow).getValues().flat();
var start = spreadsheet.getRange('C3:C' + lastRow).getValues().flat();
var end = spreadsheet.getRange('C3:C' + lastRow).getValues().flat();
name.forEach((n, i) => {
try {
var id = eventCal.createEvent(n, new Date(start[i].getTime()), new Date(end[i].getTime())).getId();
console.log(id)
} catch (e) {
console.log(i + ' ' + e)
}
})
Logger.log('Reminder is added to your calendar');
}