Calendar
Choose one date, several dates, or a range from a month grid.
Calendar shows dates directly on the page. Use it for a booking flow, a schedule, or any place where the dates should stay visible. For a text field that opens a calendar, use Date Picker.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
</script>
<template>
<Calendar default-value="2026-10-16">
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</template>Installation
npm install @ui-sdk/vue @ui-sdk/coreComposition
Use the following composition to build a Calendar:
Calendar
โโโ CalendarPrevious
โโโ CalendarHeading
โโโ CalendarNext
โโโ CalendarGrid
โโโ CalendarWeekdays
โ โโโ CalendarWeekday
โโโ CalendarWeeks
โโโ CalendarDayThe heading names the displayed month. Previous and Next change it, and a grid holds its weekday headers and dates. The weekday and week helpers render the table structure, while you render each header and date.
An empty Calendar renders the default structure, and an empty CalendarGrid renders its headers and weeks. Write the parts out to add your classes and content. Each grid is named by its month and has the grid role.
Usage
Import the parts and put them together:
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
</script>
<template>
<Calendar default-value="2026-10-16">
<CalendarPrevious />
<CalendarHeading />
<CalendarNext />
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</template>Values
Dates are ISO strings such as "2026-10-16", with no time or time zone attached. No date library is needed. The date helpers handle arithmetic; Intl formats names and labels.
| Mode | Value |
|---|---|
"single" (default) | A date string or null. |
"multiple" | A sorted array of date strings. |
"range" | [start, end] or null. |
A value with the wrong shape for its mode is treated as no selection.
Range
mode="range" chooses a start and then an end. Moving the pointer or focus previews the range; the value changes once both ends are chosen. A date before the start ends it too, and becomes the start. Escape cancels an unfinished range.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
</script>
<template>
<Calendar
mode="range"
:months="2"
month-format="short"
:default-value="['2026-10-12', '2026-10-16']"
>
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<div data-slot="row">
<CalendarGrid :offset="0">
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
<CalendarGrid :offset="1">
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</div>
</Calendar>
</template>Multiple
mode="multiple" toggles each date independently. Its value is a sorted array, even when dates were chosen in another order.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
type CalendarValue,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
import { ref } from "vue"
const dates = ref<string[]>(["2026-10-07", "2026-10-16", "2026-10-26"])
function onValueChange(value: CalendarValue) {
dates.value = value as string[]
}
</script>
<template>
<div>
<Calendar mode="multiple" :value="dates" @update:value="onValueChange">
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</div>
</template>Unavailable Dates
unavailable accepts a date, { from, to }, { weekday: [0, 6] } for weekends, { before }, { after }, a predicate, or an array of these matchers. Weekday zero is Sunday.
Unavailable dates cannot be selected, but stay focusable so keyboard and screen reader users can discover them. They expose aria-disabled and data-unavailable.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
const unavailable = [
"2026-10-08",
{ from: "2026-10-20", to: "2026-10-23" },
{ weekday: [0, 6] },
]
</script>
<template>
<Calendar :unavailable="unavailable">
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</template>Deselect
deselectable lets a second press on the selected date clear it, in single mode. Without it, a second press keeps the date selected.
Min and Max
min and max set the earliest and latest selectable dates. Dates outside those bounds cannot receive focus. Arrow keys stop at the bounds, and Previous and Next stop at their months.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
</script>
<template>
<Calendar default-value="2026-10-16" min="2026-10-05" max="2026-11-20">
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</template>Disabled and Read Only
disabled prevents focus, selection, and month navigation. read-only allows navigation so dates can be inspected, but keeps the selected value unchanged.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
</script>
<template>
<Calendar disabled default-value="2026-10-16">
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</template><script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
</script>
<template>
<Calendar read-only default-value="2026-10-16">
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</template>Two Months
Set months to 2 and render grids with offsets 0 and 1. Arrow keys move between the grids without turning the page. Dates that another visible month already shows leave an empty cell, so each date appears once.
page-by="page" makes Previous, Next, and navigation beyond the visible grids move by the full number of months.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
</script>
<template>
<Calendar
:months="2"
page-by="page"
month-format="short"
default-value="2026-10-16"
>
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<div data-slot="row">
<CalendarGrid :offset="0">
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
<CalendarGrid :offset="1">
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</div>
</Calendar>
</template>Fixed Weeks
fixed-weeks renders six week rows in every month. Set show-outside-days to false to leave dates from neighboring months blank.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
</script>
<template>
<Calendar fixed-weeks :show-outside-days="false" default-month="2026-02">
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</template>Month and Year Selects
CalendarMonthSelect and CalendarYearSelect are native selects for jumping directly to a date, such as a birthday. The year options run from min to max, or ten years either side of the current year shown when bounds are missing. Months outside the bounds are disabled.
They update the first displayed month with the select-change reason. Their state exposes the options if you want to render a different select.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarMonthSelect,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
CalendarYearSelect,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
</script>
<template>
<Calendar default-month="1990-06" min="1920-01-01" max="2026-10-16">
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<div data-slot="row">
<CalendarMonthSelect />
<CalendarYearSelect />
</div>
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</template>Custom Month and Year Selects
The month and year selects are native select elements. To use your own select, control the calendar's month and drive it from your select's value, as with the Select component here. Keep a CalendarHeading in the calendar, visually hidden if you like, so the grid stays named.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import {
Select,
SelectContent,
SelectItem,
SelectItemIndicator,
SelectTrigger,
SelectValue,
} from "@ui-sdk/vue/select"
import { CheckIcon, ChevronDownIcon } from "@lucide/vue"
import { computed, ref } from "vue"
const months = [
"January",
"February",
"March",
"April",
"May",
"June",
"July",
"August",
"September",
"October",
"November",
"December",
].map((label, index) => ({ value: String(index + 1).padStart(2, "0"), label }))
const years = ["2024", "2025", "2026", "2027", "2028"].map((year) => ({
value: year,
label: year,
}))
const month = ref("2026-10")
const year = computed(() => month.value.split("-")[0])
const monthOfYear = computed(() => month.value.split("-")[1])
</script>
<template>
<Calendar
v-model:month="month"
default-value="2026-10-16"
min="2024-01-01"
max="2028-12-31"
>
<div data-slot="row">
<CalendarHeading />
<Select
:items="months"
:value="monthOfYear"
@value-change="(next) => next && (month = `${year}-${next}`)"
>
<SelectTrigger aria-label="Month">
<SelectValue />
<ChevronDownIcon />
</SelectTrigger>
<SelectContent>
<SelectItem
v-for="option in months"
:key="option.value"
:value="option.value"
>
{{ option.label }}
<SelectItemIndicator>
<CheckIcon />
</SelectItemIndicator>
</SelectItem>
</SelectContent>
</Select>
<Select
:items="years"
:value="year"
@value-change="(next) => next && (month = `${next}-${monthOfYear}`)"
>
<SelectTrigger aria-label="Year">
<SelectValue />
<ChevronDownIcon />
</SelectTrigger>
<SelectContent>
<SelectItem
v-for="option in years"
:key="option.value"
:value="option.value"
>
{{ option.label }}
<SelectItemIndicator>
<CheckIcon />
</SelectItemIndicator>
</SelectItem>
</SelectContent>
</Select>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</template>Language
locale controls month names, weekday headers, and full date labels. If you omit it, Calendar reads the surrounding pageโs lang after it mounts, with the browserโs language as a fallback. The initial server and client render use English, so they always match. The first weekday follows the locale, and so changes after mount too, unless week-starts-on sets it. weekday-format accepts "narrow", "short", or "long".
Previous and Next are named "Previous month" and "Next month". Pass aria-label to name them in another language. Dates remain Gregorian. Localized year systems, such as Buddhist or Japanese era years, can still appear in the labels.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
</script>
<template>
<Calendar
locale="de-DE"
:week-starts-on="1"
weekday-format="narrow"
default-value="2026-10-16"
>
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</template>Name Formats
Set weekday-format for the weekday headers and month-format for the heading and the month select. Both take "narrow", "short" or "long", and follow the calendar's locale. Screen readers still hear full names: the grid and each day keep their long labels.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
</script>
<template>
<Calendar
:months="2"
page-by="page"
default-value="2026-10-16"
weekday-format="narrow"
month-format="short"
>
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<div data-slot="row">
<CalendarGrid :offset="0">
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
<CalendarGrid :offset="1">
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</div>
</Calendar>
</template>Custom Days
A dayโs slot receives its state, including the date, label, selection, and whether it is outside the month. This example adds a price below each day. Weekday headers can have custom content too.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
const priceOf = (date: string) => 80 + ((Number(date.slice(8)) * 7) % 5) * 10
</script>
<template>
<Calendar today="2026-10-16" default-value="2026-10-16">
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday v-slot="{ state }" :index="index">
<abbr
:title="state.name"
:data-weekend="
state.weekday === 0 || state.weekday === 6 || undefined
"
>
{{ state.label }}
</abbr>
</CalendarWeekday>
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay v-slot="{ state }" :value="cell.date">
<span data-slot="stack">
<span>{{ state.label }}</span>
<span v-if="!state.outside && !state.disabled" data-slot="hint"
>${{ priceOf(state.date) }}</span
>
</span>
</CalendarDay>
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</template>Range Limits
min-days and max-days count both ends. A three-day range includes its start, the day between, and its end. A press that would break a limit keeps the start, so another end can be chosen. Until then, the dates that can't end the range are disabled.
A range cannot include an unavailable date unless allow-unavailable is set. That allows unavailable dates between the ends; they still cannot be chosen as an endpoint.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
</script>
<template>
<Calendar
mode="range"
:min-days="3"
:max-days="8"
:unavailable="{ from: '2026-10-17', to: '2026-10-18' }"
allow-unavailable
>
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</template>Range in Progress
The root's state has anchor, the start while an end is being picked, and focused, the date with the Tab stop. @anchor-change and @focused-change report them before they change, to show the range being picked outside the calendar, and canceling either keeps things as they were. A day that takes focus because the months turned reports nothing.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
import { useLog } from "./log"
const log = useLog()
</script>
<template>
<div>
<Calendar
mode="range"
@anchor-change="
(anchor) => log(anchor ? `Started on ${anchor}` : 'Range finished')
"
@focused-change="(focused) => log(`Focus on ${focused}`)"
>
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</div>
</template>Controlled
The selection and displayed month are separate. value uses the shape for the chosen mode; month names the first displayed month, such as "2026-10".
Use v-model:value and v-model:month to control them, and @value-change and @month-change to see each change. Use default-value and default-month for initial state. Change details include a reason; details.cancel() rejects the change. State and Events covers the binding pattern, and the reason tables list Calendarโs reasons.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
type CalendarMonthChangeReason,
type CalendarValue,
type CalendarValueChangeReason,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
import { ref } from "vue"
import { useLog } from "./log"
const value = ref<CalendarValue>("2026-10-16")
const month = ref("2026-10")
const log = useLog()
function onValueChange(
next: CalendarValue,
details: { reason: CalendarValueChangeReason }
) {
log(`Selected ${String(next)} (${details.reason})`)
}
function onMonthChange(
next: string,
details: { reason: CalendarMonthChangeReason }
) {
log(`Showing ${next} (${details.reason})`)
}
</script>
<template>
<div>
<Calendar
v-model:value="value"
v-model:month="month"
@value-change="onValueChange"
@month-change="onMonthChange"
>
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</div>
</template>Today
Today gets aria-current="date" and data-today. When there is no selection or starting month, the calendar opens on todayโs month. It reads today on the client; set today to pin a date explicitly.
time-zone determines which date is today. It does not convert the selected date into another time zone.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
</script>
<template>
<div>
<Calendar time-zone="Pacific/Kiritimati">
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
<p data-slot="hint">
Today is marked as it is in Kiritimati, the first place to see each new
day.
</p>
</div>
</template>Driving It from Anywhere
A createCalendarController() instance can set the value, change months, and focus a date. Focusing a date in another month shows that month first. Controllers covers setup and lifecycle.
<script setup lang="ts">
import { todayDate } from "@ui-sdk/core/date"
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
createCalendarController,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
const calendar = createCalendarController()
function select(date: string) {
calendar.setValue(date)
calendar.focus(date)
}
</script>
<template>
<div data-slot="stack">
<div data-slot="controls">
<button type="button" @click="select('2026-12-25')">
Go to Christmas
</button>
<button type="button" @click="select(todayDate())">Today</button>
</div>
<Calendar
:controller="calendar"
default-value="2026-10-16"
default-month="2026-10"
>
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</div>
</template>Presets
Drive a range calendar from buttons for the ranges people pick most. Each preset sets the value through the controller and moves focus to its first day, using the date helpers for the arithmetic.
<script setup lang="ts">
import { addDays, endOfMonth, startOfMonth } from "@ui-sdk/core/date"
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
CalendarWeekdays,
CalendarWeeks,
createCalendarController,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
const today = "2026-10-16"
const presets = [
{ label: "Last 7 Days", range: [addDays(today, -6), today] },
{ label: "This Month", range: [startOfMonth(today), endOfMonth(today)] },
{ label: "Next 30 Days", range: [today, addDays(today, 29)] },
] as const
const calendar = createCalendarController()
function choose(range: readonly [string, string]) {
calendar.setValue([...range])
calendar.focus(range[0])
}
</script>
<template>
<div data-slot="stack">
<div data-slot="controls">
<button
v-for="preset in presets"
:key="preset.label"
type="button"
data-size="sm"
@click="choose(preset.range)"
>
{{ preset.label }}
</button>
</div>
<Calendar
mode="range"
:controller="calendar"
:today="today"
default-month="2026-10"
>
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<ChevronLeftIcon aria-hidden="true" />
</CalendarPrevious>
<CalendarHeading />
<CalendarNext data-variant="ghost">
<ChevronRightIcon aria-hidden="true" />
</CalendarNext>
</div>
<CalendarGrid>
<CalendarWeekdays v-slot="{ index }">
<CalendarWeekday :index="index" />
</CalendarWeekdays>
<CalendarWeeks v-slot="{ cell }">
<CalendarDay :value="cell.date" />
</CalendarWeeks>
</CalendarGrid>
</Calendar>
</div>
</template>Custom Rendering
The gridโs slot receives its state, with its month, label, weekdays, and weeks, when you need to write the table yourself. Preserve empty cells marked hidden so dates shown by another month do not appear twice. Parts and Composition covers changing a partโs element without losing its behavior.
<script setup lang="ts">
import {
Calendar,
CalendarDay,
CalendarGrid,
CalendarHeading,
CalendarNext,
CalendarPrevious,
CalendarWeekday,
} from "@ui-sdk/vue/calendar"
import { ChevronLeftIcon, ChevronRightIcon } from "@lucide/vue"
function isoWeek(date: string) {
const day = new Date(`${date}T00:00:00Z`)
day.setUTCDate(day.getUTCDate() + 3 - ((day.getUTCDay() + 6) % 7))
const firstThursday = new Date(Date.UTC(day.getUTCFullYear(), 0, 4))
const days = (day.getTime() - firstThursday.getTime()) / 86400000
return 1 + Math.round((days - 3 + ((firstThursday.getUTCDay() + 6) % 7)) / 7)
}
</script>
<template>
<Calendar default-value="2026-10-16" :week-starts-on="1">
<div data-slot="row">
<CalendarPrevious data-variant="ghost">
<template #render="{ props, state: step }">
<button v-bind="props" :title="`Show ${step.month}`">
<ChevronLeftIcon />
</button>
</template>
</CalendarPrevious>
<CalendarHeading v-slot="{ state: heading }">{{
heading.label
}}</CalendarHeading>
<CalendarNext data-variant="ghost">
<ChevronRightIcon />
</CalendarNext>
</div>
<CalendarGrid v-slot="{ state: grid }">
<thead>
<tr>
<th scope="col">
<abbr title="Week">Wk</abbr>
</th>
<CalendarWeekday
v-for="(weekday, index) in grid.weekdays"
:key="weekday"
:index="index"
/>
</tr>
</thead>
<tbody>
<tr v-for="week in grid.weeks" :key="week[0]!.date">
<th scope="row" data-slot="hint">{{ isoWeek(week[0]!.date) }}</th>
<template v-for="cell in week" :key="cell.date">
<td v-if="cell.hidden"></td>
<CalendarDay v-else :value="cell.date" />
</template>
</tr>
</tbody>
</CalendarGrid>
</Calendar>
</template>Styling
Use data-selected, data-today, data-outside, data-unavailable, and data-disabled to style dates. A range also exposes its start, middle, end, and unfinished preview. Navigation buttons also get data-disabled when they reach the bounds.
Each part has a data-slot, such as calendar-day, and its state attributes are listed under Data Attributes.
Data Attributes
Calendar
[data-slot="calendar"]
| Attribute | What it means |
|---|---|
data-mode | singlemultiplerangeHow the calendar selects. |
data-readonly | Present when dates can be focused but not picked. |
data-disabled | Present on the root, grids and selects when the calendar is disabled, on a day that can't be picked, and on Previous or Next at min or max. |
CalendarPrevious
[data-slot="calendar-previous"]
| Attribute | What it means |
|---|---|
data-disabled | Present on the root, grids and selects when the calendar is disabled, on a day that can't be picked, and on Previous or Next at min or max. |
CalendarNext
[data-slot="calendar-next"]
| Attribute | What it means |
|---|---|
data-disabled | Present on the root, grids and selects when the calendar is disabled, on a day that can't be picked, and on Previous or Next at min or max. |
CalendarMonthSelect
[data-slot="calendar-month-select"]
| Attribute | What it means |
|---|---|
data-disabled | Present on the root, grids and selects when the calendar is disabled, on a day that can't be picked, and on Previous or Next at min or max. |
CalendarYearSelect
[data-slot="calendar-year-select"]
| Attribute | What it means |
|---|---|
data-disabled | Present on the root, grids and selects when the calendar is disabled, on a day that can't be picked, and on Previous or Next at min or max. |
CalendarGrid
[data-slot="calendar-grid"]
| Attribute | What it means |
|---|---|
data-disabled | Present on the root, grids and selects when the calendar is disabled, on a day that can't be picked, and on Previous or Next at min or max. |
CalendarDay
[data-slot="calendar-day"]
| Attribute | What it means |
|---|---|
data-value | 2026-10-012026-10-142026-10-162026-10-182026-10-242026-09-30A day's ISO date. |
data-selected | Present on selected days. In a range, every day from start to end. |
data-today | Present on today, beside aria-current="date". |
data-disabled | Present on the root, grids and selects when the calendar is disabled, on a day that can't be picked, and on Previous or Next at min or max. |
data-unavailable | Present on a day unavailable names. It stays focusable. |
data-outside | Present on a day of the month before or after its grid's. |
data-range-start | Present on the day a range starts, including one being picked. |
data-range-middle | Present on the days inside a range, between its ends. |
data-range-end | Present on the day a range ends, including one being picked. |
data-preview | Present on the days of a range being picked, from its start to the day under the pointer or focus. |
API Reference
Props are the same as below, and callbacks are events.
Calendar
mode?CalendarMode- How many dates it selects: one, any number, or a range from a start to an end.
value?CalendarValue- The selected value: an ISO date for
"single", a list for"multiple",[start, end]for"range", ornull. Pass it to control the calendar. defaultValue?CalendarValue- The value it starts with, when uncontrolled.
@value-change((value: CalendarValue, details: ChangeDetails<CalendarValueChangeReason>) => void)- Runs when a date is pressed (
"item-press"), with Enter or Space too, or a controller sets the value ("imperative"). A range changes once both ends are picked.details.cancel()keeps the value. month?string- The first month shown, like
"2026-10". Pass it to control the calendar. defaultMonth?string- The first month it shows, when uncontrolled. Defaults to the selected date's month, else today's.
@month-change((month: ISOMonth, details: ChangeDetails<CalendarMonthChangeReason>) => void)- Runs when the months shown want to change: Previous or Next, a key moving focus to another month, a press on a day of another month, or a controller.
min?string- The earliest date that can be picked. Keys stop there, and Previous stops at its month.
max?string- The latest date that can be picked.
unavailable?DateMatchers- Dates that can't be picked, like booked days, as data: ISO dates,
{ from, to },{ weekday: [0, 6] }for weekends,{ before },{ after }, or a function. They stay focusable, so keyboard users hear them. disabled?boolean- Whether nothing can be picked or focused.
readOnly?boolean- Whether dates can be focused but not picked.
deselectable?boolean- Whether pressing the selected date again clears it, in
"single"mode. @focused-change((date: ISODate, details: ChangeDetails<CalendarFocusedChangeReason>) => void)- Runs before keys, a press or
focus()move focus to another day. Canceling keeps focus where it was. @anchor-change((anchor: ISODate | null, details: ChangeDetails<CalendarAnchorChangeReason>) => void)- Runs before a press starts a range, or ends it or Escape drops it, with
null. Canceling keeps the start as it was. months?number- How many months show side by side, each in its own grid.
pageBy?"month" | "page"- Whether Previous, Next and keys turn one month, or all the months shown.
locale?string- The language of the names and labels. Defaults to the page's
lang, then the browser's. weekStartsOn?number- The first day of the week, 0 for Sunday. Defaults to the locale's.
weekdayFormat?"long" | "narrow" | "short"- How weekday headers are written.
monthFormat?"long" | "narrow" | "short"- How month names are written, in the heading and the month select.
fixedWeeks?boolean- Whether every month shows six weeks, so the calendar doesn't change height.
showOutsideDays?boolean- Whether the days of the months before and after show at the edges.
today?string- Today's date, for
aria-currentand the starting month. Defaults to today intimeZone, read on the client. timeZone?string- The time zone that says what day today is, like
"America/New_York". Defaults to the browser's. minDays?number- The fewest days a range can span, counting both ends.
maxDays?number- The most days a range can span, counting both ends.
allowUnavailable?boolean- Whether a range may hold unavailable dates, like a stay over a booked night.
controller?object- Drives it from anywhere. Create one with
createCalendarController(). debug?boolean- Logs every state change with its reason to the console, in development builds.
CalendarPrevious
Shows the previous month. Renders a button that is disabled at min.
CalendarHeading
Names the months shown, like "October 2026". Renders an h2 the grid is labelled by, and screen readers hear it change.
CalendarNext
Shows the next month. Renders a button that is disabled at max.
CalendarMonthSelect
A native select of the months, in the locale, that changes the first month shown.
CalendarYearSelect
A native select of the years from min to max, or 10 either side of the year shown.
CalendarGrid
offset?number- Which of the months shown it is, from 0.
CalendarWeekdays
Renders the header row. Its default slot receives each weekday's index.
CalendarWeekday
indexnumber- The column, from 0.
CalendarWeeks
Renders the week rows. Its default slot receives each cell, with its date.
CalendarDay
valuestring- Its ISO date.
offset?number- The offset of the grid it's in.
State
What render functions, state-based class names and children functions receive, per part.
Calendar:
valueCalendarValue- The selected value.
monthstring- The first month shown.
modeCalendarMode- How it selects.
disabledboolean- Whether nothing can be picked or focused.
readOnlyboolean- Whether dates can be focused but not picked.
focusedstring | null- The date with the tab stop,
nulluntil days render in the browser. anchorstring | null- A range's start while its end is being picked, else
null.
CalendarHeading:
monthstring- The first month shown, to format the heading yourself.
labelstring- The months shown in
monthFormat, like "October 2026", or "October โ November 2026".
CalendarMonthSelect and CalendarYearSelect:
valuenumber- The first month shown's month, 1 to 12, or its year.
optionsCalendarSelectOption[]- Every month, or the years from
mintomax(10 either side of the year shown without them). disabledboolean- Whether the calendar's
disabledoption is on. Inside a Date Picker, a disabled<fieldset>around the picker counts too.
CalendarPrevious and CalendarNext:
monthstring- The first month it shows.
disabledboolean- Whether it can't go further, past
minormax.
CalendarGrid:
monthstring- The month it shows: the first month shown, plus its
offset. labelstring- The month's name and year in
monthFormat, like "October 2026". weekdaysnumber[]- The weekday of each column, 0 for Sunday, in the order they show.
weeksCalendarGridCell[][]- The weeks, each seven cells. Render a day for each cell that isn't hidden.
CalendarWeekday:
weekdaynumber- The weekday, 0 for Sunday.
labelstring- Its name, in
weekdayFormat. namestring- Its full name, which screen readers hear.
CalendarDay:
datestring- Its ISO date.
labelstring- The day of the month in the locale's digits, like "16".
selectedboolean- Whether it's selected. In a range, every date from start to end is.
todayboolean- Whether it's the
todayoption's date, or else today intimeZone, read once the calendar runs in the browser. outsideboolean- Whether it belongs to the month before or after its grid's.
disabledboolean- Whether it can't be picked: outside
minandmax, unavailable, unable to end the range being picked, or the calendar is disabled. unavailableboolean- Whether
unavailablenames it. rangeStartboolean- Whether a range starts here, including one being picked.
rangeEndboolean- Whether a range ends here, including one being picked.
inRangeboolean- Whether it's inside a range, ends included, including one being picked.
Reasons
details.reason says why the value changed:
item-pressMouseEvent | KeyboardEvent- A member of a collection was chosen: a menu item, a tab, a radio or a checkbox item.
imperativenone- A controller or
apicall, or a property set on a web component.
And why the month changed:
item-pressMouseEvent | KeyboardEvent- A member of a collection was chosen: a menu item, a tab, a radio or a checkbox item.
imperativenone- A controller or
apicall, or a property set on a web component. previous-pressMouseEvent | KeyboardEvent- A pagination's or a carousel's Previous part was pressed.
next-pressMouseEvent | KeyboardEvent- A pagination's or a carousel's Next part was pressed.
list-navigationKeyboardEvent- Arrow, Home or End keys moved the selection, typing picked an item, or Ctrl or โ with A selected every item of a listbox.
select-change
Why focus moves to another day:
item-pressMouseEvent | KeyboardEvent- A member of a collection was chosen: a menu item, a tab, a radio or a checkbox item.
imperativenone- A controller or
apicall, or a property set on a web component. list-navigationKeyboardEvent- Arrow, Home or End keys moved the selection, typing picked an item, or Ctrl or โ with A selected every item of a listbox.
focus-inFocusEvent- Keyboard focus moved into the component, which stops a rotating carousel, as the carousel pattern asks, or onto a canvas item, which brought it into view, or onto a calendar's day another way, like a screen reader's.
And why a range's start changed:
item-pressMouseEvent | KeyboardEvent- A member of a collection was chosen: a menu item, a tab, a radio or a checkbox item.
escape-keyKeyboardEvent- Escape, or a submenu's close key (ArrowLeft in left-to-right layouts).
Controller
Create one with createCalendarController() and pass it as controller. Every write method takes an optional { reason, event } and returns false when the change is canceled, there's nowhere to go, or the calendar is disabled or read-only.
getValue()() => CalendarValue- The selected value: an ISO date, a list of them, or a
[start, end]range. setValue(value, options?)(value: CalendarValue, options?: CalendarChangeOptions<CalendarValueChangeReason> | undefined) => boolean- Selects a value. Returns false when canceled, unchanged, disabled, read-only, or holding a date people can't pick, like one past
max. getMonth()() => string- The first month shown, like
"2026-10". setMonth(month, options?)(month: string, options?: CalendarChangeOptions<CalendarMonthChangeReason> | undefined) => boolean- Shows a month first. Returns false when canceled or unchanged.
previous(options?)(options?: CalendarChangeOptions<CalendarMonthChangeReason> | undefined) => boolean- Shows the months before, as the Previous part does.
next(options?)(options?: CalendarChangeOptions<CalendarMonthChangeReason> | undefined) => boolean- Shows the months after, as the Next part does.
focus(date?)(date?: string | undefined) => void- Focuses a date, turning the months to show it, or the date with the tab stop.
Events
Events get the new value first, then the details. v-model only updates when the event wasn't canceled.
| Binding | On | Receives |
|---|---|---|
v-model:value | Calendar | The selected value |
v-model:month | Calendar | The first month shown |
@value-change | Calendar | (value, details): the new value, and the reason |
@month-change | Calendar | (month, details): the new first month, and the reason |
@focused-change | Calendar | (date, details): the day focus moves to, and the reason |
@anchor-change | Calendar | (date, details): a range's start, or null once it ends, and the reason |
Accessibility
It follows the grid of the WAI-ARIA date picker dialog: each month is a grid named by its month, weekday headers are columnheaders named by their full names, and each day is a focusable gridcell named by its full date, like "Friday, October 16, 2026", with aria-selected, aria-disabled and aria-current="date". A grid that selects several dates or a range is aria-multiselectable. Every line below is an automated test.
Keyboard
The grid has one Tab stop: the selected date when visible, otherwise today, otherwise the first available date. Moving into another month shows it and then focuses the date.
| Key | Action |
|---|---|
| Left / Right Arrow | Move one day, following the pageโs direction. |
| Up / Down Arrow | Move one week. |
| Home / End | Move to the first or last day of the week. |
| Page Up / Page Down | Move one month, keeping the day where possible. |
| Shift+Page Up / Shift+Page Down | Move one year. |
| Enter / Space | Select the focused date. |
| Escape | Cancel an unfinished range. |
Tested Behavior
- The calendar shows a month as a grid of days under weekday headers.
- The selected date holds the tab stop, else today.
- Tab leaves the grid after one stop.
- Arrow keys move focus by day and week.
- Moving past the month's edge shows the next month and focuses the day there.
- Page Up and Page Down move by month, and with Shift by year.
- The day of the month stays the same, or the month's last, when moving by month.
- Home and End go to the first and last day of the week.
- The week starts on the locale's first day.
- Pressing a day selects it.
- Enter on a focused day selects it.
- Space on a focused day selects it.
- Previous and Next show the month before and after, and the heading announces it.
- Min and max stop keys there, and Previous and Next at their months.
- Unavailable dates can be focused but not selected.
- In multiple mode, presses toggle dates.
- In range mode, two presses pick a range, previewed in between.
- In range mode, keys preview the end and Escape drops the start.
- A range keeps to its fewest and most days, and keeps its start.
- Two months show side by side, and focus moves between them without turning.
- Pressing a day of the next month selects it and shows its month.
- Pressing another month's day before min keeps the month shown.
- Pressing another month's day before min leaves focus on the day that had it.
- A controlled calendar shows what the app passes.
- A controller turns to a date and focuses it.
- A disabled calendar has no tab stop and selects nothing.
- A read-only calendar moves focus but selects nothing.
- They show the first month shown and turn the calendar, with the select-change reason.
- Years run from min to max, and months past them are disabled.
- They follow the page's language.
Runs in React, Vue and web components.
Beyond the baseline:
- Keys pressed without waiting still land on the right day.
- A day of next month takes focus even when its month renders after the key.
Runs in React, Vue and web components.