Now and today
Today's highlight, the now indicator and the clock.
The current time sets which day is today and where the now indicator sits. The calendar reads it from a clock:
| Where | Field |
|---|---|
| Day-grid days | isToday, rendered as data-today |
| Time-grid columns | isToday, and now: the fraction of the day for the now indicator |
| Timelines | Day headers' isToday, and the layout's now: the fraction of the range, absent outside it |
| State | state.now, a Temporal.ZonedDateTime in timeZone |
| Navigation | today() goes to today in timeZone |
Clock
Without a clock option, the calendar ticks every minute. Each tick re-derives the state only when the time changed.
Two clocks are built in:
// tick every 15 seconds instead of every minute
export const clock = intervalClock({ every: Temporal.Duration.from({ seconds: 15 }) });fixedClock(instant) never ticks, for tests, stories and screenshots. Any { now, subscribe } object is a clock.
The clock starts when the calendar mounts and stops when it unmounts. Before that, the current time comes from initialNow
if given; see server rendering.
Freezing time
// a frozen "now", for tests, stories and screenshots
export const useFrozenCalendar = () =>
useCalendar({
timeZone,
views,
features,
view: 'week',
date: Temporal.PlainDate.from('2026-03-11'),
events: bookings,
onNavigate: () => {},
clock: fixedClock(Temporal.Instant.from('2026-03-11T14:30:00Z')),
});Now indicator
Render TimeGridViewNowIndicator in every column; it renders only in today's column, at column.now. See the
week and day view.
In timelines, render one TimelineViewNowIndicator with the layout as model; it renders only while now is in
the visible range.