Server-Side Scheduling

@forcecalendar/core is DOM-free, dependency-free, pure ES modules — it runs anywhere JavaScript does, including runtimes that ban eval and dynamic code such as Cloudflare Workers. That makes it a server-side scheduling engine, not just a UI companion.

What you can do server-side

• Expand recurrence rules — turn an RFC 5545 RRULE into concrete occurrences for a date range
• Detect conflicts — time, attendee, and resource overlap across event sets
• Import/export ICS — parse calendar feeds and generate iCalendar files
• Search — full-text queries across large event sets

Expanding recurrences in Node

import { RecurrenceEngine } from '@forcecalendar/core';

const occurrences = RecurrenceEngine.expandEvent(
  {
    id: 'standup',
    title: 'Team Standup',
    start: new Date('2026-01-05T09:00:00Z'),
    end: new Date('2026-01-05T09:15:00Z'),
    recurring: true,
    recurrenceRule: 'FREQ=WEEKLY;BYDAY=MO,WE,FR',
    timeZone: 'America/New_York'
  },
  new Date('2026-01-01'),
  new Date('2026-03-31'),
  500 // max occurrences
);
// -> [{ start, end, recurringEventId, timezone, originalStart }, ...]

Daily and weekly rules use a numeric fast path (pure timestamp arithmetic between DST transitions), so expanding multi-year series takes fractions of a millisecond — safe inside request handlers.

Generating ICS

import { Calendar, ICSHandler } from '@forcecalendar/core';

const calendar = new Calendar({ timeZone: 'UTC' });
calendar.addEvent({
  id: 'evt-1',
  title: 'Quarterly Review',
  start: new Date('2026-04-01T14:00:00Z'),
  end: new Date('2026-04-01T15:00:00Z'),
  recurring: true,
  recurrenceRule: 'FREQ=MONTHLY;INTERVAL=3;COUNT=4'
});

const ics = new ICSHandler(calendar).export({ calendarName: 'Reviews' });
// -> "BEGIN:VCALENDAR..." — serve with Content-Type: text/calendar

Edge runtimes

The engine deploys to Cloudflare Workers unmodified — see the runnable Worker example, which exposes /occurrences and /ics endpoints and includes a smoke test.

Timezones

Expansion is timezone-aware per occurrence: pass an IANA timeZone on the event (or as the fifth argument to expandEvent) and DST transitions are handled for you, including half-hour and 45-minute offset zones.