server.ts

let events = [];
for (const calendar of calendars) {
    console.log(calendar);
    ical.fromURL(calendar, {}, (err, data) => {
      for (var k in data) {
        if (data.hasOwnProperty(k)) {
          const event = data[k];
          const eventStart = moment(event.start);
          const now = moment();
          const later = moment().add(1, 'days');

          //console.log(eventStart.format('llll'));
          if (eventStart.isBetween(now, later)) {
            events.push(eventStart);
            console.log('hi');
          }
        }
      }
    });
  }
  console.log(events);