@kalyx/core

Platform-independent date logic powering the seven Kalyx pickers — single date, range, time, date+time, month, year, week. Types, adapters, and UTC-safe utilities.

Most users should install @kalyx/react directly — it re-exports what you need. Install @kalyx/core only if you're building your own picker layer or a custom platform adapter.

📚 Full docs: kalyx-docs-site.vercel.app/docs/api/core

Install

pnpm add @kalyx/core

What's inside

Types

import type {
  ISODateString,
  DisabledRule,
  DateRange,
  CalendarDay,
  CalendarGrid,
  WeekStartsOn,
  CalendarOptions,
  DateAdapter,
  TimeValue,
} from '@kalyx/core';

Adapter

@kalyx/core defines the DateAdapter interface but ships no implementation — the package is date-library-agnostic. Install a separate adapter package:

import { DateFnsAdapter } from '@kalyx/adapter-date-fns';
// UTC-safe adapter built on date-fns v4.

Bring your own adapter by implementing the DateAdapter interface from @kalyx/core against any date library (dayjs, luxon, Temporal, etc.).

Calendar utilities

import { getCalendarDays, isDateDisabled, minDate, maxDate } from '@kalyx/core';

Date helpers

import { normalizeISO, parseInputValue } from '@kalyx/core';

Time helpers

import {
  setTime, getTime,
  parseTimeString, formatTimeString, formatTimeFromISO,
  to12Hour, to24Hour,
  generateHours, generateMinutes,
  isSameTime,
} from '@kalyx/core';

Locale helpers

import {
  getMonthName, formatMonthYear,
  getWeekdayNames, formatFullDate,
} from '@kalyx/core';

Timezone helpers

DST-aware timezone utilities used by every picker when displayTimezone is set.

import {
  formatInTimezone,
  startOfDayInTimezone,
  isSameDayInTimezone,
  todayInTimezone,
  getTimezoneOffsetMinutes,
  civilMidnightFromUtcDay,
  getTimeInTimezone,
  setTimeInTimezone,
} from '@kalyx/core';

Accessibility labels

Default ARIA labels (English). Override via the labels prop on any picker Root.

import {
  DEFAULT_DATEPICKER_LABELS,
  DEFAULT_RANGEPICKER_LABELS,
  DEFAULT_TIMEPICKER_LABELS,
  DEFAULT_DATETIMEPICKER_LABELS,
} from '@kalyx/core';

Principles

• All dates are ISO 8601 UTC strings — never Date objects.
• UTC-only arithmetic — uses getUTC* methods, never local-timezone variants.
• Adapter abstraction — swap date engines by implementing DateAdapter.
• Pure functions — zero side effects, fully testable.

License

MIT