Core Engine

@forcecalendar/core

Zero-dependency calendar logic for enterprise applications. Runs anywhere JavaScript runs: browser, Node, serverless, and edge.

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Dependencies

MIT

License

.d.ts

TypeScript

~35KB

Min + gzip

Explore

Module tour

Calendar Engine

Complete control over calendar state, navigation, and rendering logic without DOM dependencies.

Month, week, and day view data, plus a list format for custom UIs
Navigation API with goToDate, next, previous
Event-driven state with subscribe/unsubscribe
setEvents(events, { reconcile: true }) applies only the diff from a snapshot and reports added, updated, and removed

Live outputrunning

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calendar.tsTypeScript

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

const calendar = new Calendar({
  locale: 'en-US',
  timeZone: 'America/New_York',
  weekStartsOn: 0
});

calendar.setView('month');
calendar.goToDate(new Date('2026-03-16'));

calendar.on('viewChange', ({ view, date }) => {
  console.log('View:', view, date);
});

Reference

API surface

Every class exported from @forcecalendar/core.

Full API documentation

Calendar: Core calendar engine with state, navigation, timezone conversion, and event management
Event: Event model with validation, normalization, and timezone-aware accessors
EventStore: Indexed event storage with range queries and conflict detection
StateManager: Reactive state management with subscribe/unsubscribe and history
DateUtils: Date math, formatting, and week/month grid helpers
EventSearch: Full-text search across event titles, descriptions, and fields
ICSParser: RFC 5545 iCalendar import and export
RecurrenceEngine: RRULE expansion with exceptions, overrides, and hard occurrence caps
EnhancedCalendar: Calendar extended with worker-backed search and RecurrenceEngineV2
ICSHandler: High-level ICS import/export API over ICSParser, including URL fetch
RecurrenceEngineV2: Extended recurrence engine with modified instances and complex DST handling
RRuleParser: Standalone RFC 5545 RRULE string parser
SearchWorkerManager: Offloads search indexing and queries to a Web Worker
InvertedIndex: Term-to-event index powering fast full-text lookups
TimezoneManager: IANA timezone conversions, DST detection, and offset math
ConflictDetector: Time, attendee, and resource overlap detection across event sets

Full API documentation at docs.forcecalendar.org/docs/api

Get started

Quick start

1
Install

Initialize

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

const calendar = new Calendar({
  locale: 'en-US',
  timeZone: 'America/New_York'
});

Add events

calendar.addEvent({
  title: 'Team Meeting',
  start: new Date('2026-03-16T10:00:00'),
  end: new Date('2026-03-16T11:00:00')
});

Start building

Documentation API Reference GitHub