Daily agenda for all Google owned calendars - google-apps-script

Question

I'm trying to get daily agenda of the events from all my calendars (personal, holidays, specific tasks etc) sent in one email.
I use the following code for one specific calendar, but don't know how to add all other owned calendars in the same code, is that even possible?
function sendAllCalendarsAgenda() {
var cal = CalendarApp.getOwnedCalendarById('?????????#group.calendar.google.com');
var events = cal.getEventsForDay(new Date());
var mailto = 'myEmailAddress#gmail.com';
if (events.length > 0) {
var body = 'Google Calendar - Events' + 'nn';
var tz = Session.getScriptTimeZone();
for (var i = 0; i < events.length; i++) {
body += Utilities.formatDate(events[i].getStartTime(), tz, 'MM:dd HH:mm') + ' ～ ';
body += Utilities.formatDate(events[i].getEndTime(), tz, 'MM:dd HH:mm') + ' :';
body += events[i].getTitle() + 'n';
}
MailApp.sendEmail(mailto, 'Google Calender - Summary', body);
}
}

Answer 1

Try this:
function sendAllCalendarsAgenda() {
const cals = CalendarApp.getAllCalendars();
let o = [];
var body = 'Google Calendar - Events Summary' + '\n\n';
cals.forEach(cal => {
var events = cal.getEventsForDay(new Date());
var mailto = 'myEmailAddress#gmail.com';
if (events.length > 0) {
var tz = Session.getScriptTimeZone();
for (var i = 0; i < events.length; i++) {
body += event[i].getTitle();
body += Utilities.formatDate(events[i].getStartTime(), tz, 'MM:dd HH:mm') + ' ～ ';
body += Utilities.formatDate(events[i].getEndTime(), tz, 'MM:dd HH:mm') + ' :';
}
o.push(body);
}
});
MailApp.sendEmail(mailto, 'Google Calendar - Summary', a.join('\n\n'));
}