feat: add support for broadcast calendar

examples/BroadcastCalendar.tsx

@@ -0,0 +1,7 @@
+import React from "react";
+
+import { DayPicker } from "react-day-picker";
+
+export function BroadcastCalendar() {
+  return <DayPicker showOutsideDays showWeekNumber broadcastCalendar />;
+}

examples/index.ts

@@ -1,5 +1,6 @@
 export * from "./AccessibleDatePicker";
 export * from "./AutoFocus";
+export * from "./BroadcastCalendar";
 export * from "./ContainerAttributes";
 export * from "./Controlled";
 export * from "./ControlledSelection";

src/DayPicker.tsx

@@ -49,7 +49,7 @@ export function DayPicker(props: DayPickerProps) {
       const dateLib = new DateLib(
         {
           locale,
-          weekStartsOn: props.weekStartsOn,
+          weekStartsOn: props.broadcastCalendar ? 1 : props.weekStartsOn,
           firstWeekContainsDate: props.firstWeekContainsDate,
           useAdditionalWeekYearTokens: props.useAdditionalWeekYearTokens,
           useAdditionalDayOfYearTokens: props.useAdditionalDayOfYearTokens
@@ -75,7 +75,8 @@ export function DayPicker(props: DayPickerProps) {
       props.locale,
       props.useAdditionalDayOfYearTokens,
       props.useAdditionalWeekYearTokens,
-      props.weekStartsOn
+      props.weekStartsOn,
+      props.broadcastCalendar
     ]);
 
   const {

src/helpers/broadcastCalendar.test.ts

@@ -0,0 +1,36 @@
+import {
+  getBroadcastWeeksInMonth,
+  startOfBroadcastWeek,
+  endOfBroadcastWeek
+} from "./broadcastCalendar";
+
+describe("Broadcast Date Functions", () => {
+  test("getBroadcastWeeksInMonth should return correct number of weeks", () => {
+    // Test for a month with 5 weeks
+    expect(getBroadcastWeeksInMonth(new Date(2023, 0, 1))).toBe(5); // January 2023
+    // Test for a month with 4 weeks
+    expect(getBroadcastWeeksInMonth(new Date(2023, 1, 1))).toBe(4); // February 2023
+  });
+
+  test("getBroadcastStartDate should return correct start date", () => {
+    // Test for a month starting on a Monday
+    expect(startOfBroadcastWeek(new Date(2023, 0, 1))).toEqual(
+      new Date(2022, 11, 26)
+    ); // December 26 2022
+    // Test for a month starting on a Wednesday
+    expect(startOfBroadcastWeek(new Date(2020, 0, 1))).toEqual(
+      new Date(2019, 11, 30)
+    ); // December 30 2019
+  });
+
+  test("getBroadcastEndDate should return correct end date", () => {
+    const startDate = startOfBroadcastWeek(new Date(2023, 0, 1));
+    expect(endOfBroadcastWeek(new Date(2023, 0, 1))).toEqual(
+      new Date(
+        startDate.getFullYear(),
+        startDate.getMonth(),
+        startDate.getDate() + 34
+      )
+    ); // January 2023
+  });
+});

src/helpers/broadcastCalendar.ts

@@ -0,0 +1,58 @@
+/** Return the number of weeks to display in the broadcast calendar. */
+export function getBroadcastWeeksInMonth(month: Date): number {
+  const NUMBER_OF_5_WEEKS = 5;
+  const NUMBER_OF_4_WEEKS = 4;
+
+  const firstDayOfMonth = new Date(month.getFullYear(), month.getMonth(), 1);
+  const dayOfWeekOfFirstDayOfMonth =
+    firstDayOfMonth.getDay() > 0 ? firstDayOfMonth.getDay() : 7;
+  const beginDate = new Date(
+    month.getFullYear(),
+    month.getMonth(),
+    month.getDate() - dayOfWeekOfFirstDayOfMonth + 1
+  );
+  const numberOfWeeks =
+    month.getMonth() ===
+    new Date(
+      beginDate.getFullYear(),
+      beginDate.getMonth(),
+      beginDate.getDate() + NUMBER_OF_5_WEEKS * 7 - 1
+    ).getMonth()
+      ? NUMBER_OF_5_WEEKS
+      : NUMBER_OF_4_WEEKS;
+  return numberOfWeeks;
+}
+
+/** Return the start date of the week in the broadcast calendar. */
+export function startOfBroadcastWeek(date: Date): Date {
+  const year = date.getFullYear();
+  const month = date.getMonth();
+
+  const firstOfMonth = new Date(year, month, 1);
+  const dayOfWeek = firstOfMonth.getUTCDay(); // 0 = Sunday, 1 = Monday, etc.
+
+  // If the first of the month is a Monday, then the broadcast month starts on that day.
+  // Otherwise, the broadcast starts on the previous Monday, and if first of the month is Sunday, then the starts on the previous week's Monday.
+  if (dayOfWeek === 1) {
+    return firstOfMonth;
+  } else if (dayOfWeek === 0) {
+    const startDate = new Date(year, month, 1 - dayOfWeek + 1 - 7);
+    return startDate;
+  } else {
+    const startDate = new Date(year, month, 1 - dayOfWeek + 1);
+    return startDate;
+  }
+}
+
+/** Return the end date of the week in the broadcast calendar. */
+export function endOfBroadcastWeek(date: Date): Date {
+  const startDate = startOfBroadcastWeek(date);
+  // end date based on the weeks to show, it is calculated by getBroadcastWeeksInMonth
+  const numberOfWeeks = getBroadcastWeeksInMonth(date);
+  const endDate = new Date(
+    startDate.getFullYear(),
+    startDate.getMonth(),
+    startDate.getDate() + numberOfWeeks * 7 - 1
+  );
+  return endDate;
+}

src/helpers/getMonths.ts

@@ -2,6 +2,10 @@ import type { DateLib } from "../classes/DateLib.js";
 import { CalendarWeek, CalendarDay, CalendarMonth } from "../classes/index.js";
 import type { DayPickerProps } from "../types/index.js";
 
+import {
+  startOfBroadcastWeek,
+  endOfBroadcastWeek
+} from "./broadcastCalendar.js";
 import { NrOfDaysWithFixedWeeks } from "./getDates.js";
 
 /** Return the months to display in the calendar. */
@@ -11,7 +15,10 @@ export function getMonths(
   /** The dates to display in the calendar. */
   dates: Date[],
   /** Options from the props context. */
-  props: Pick<DayPickerProps, "fixedWeeks" | "ISOWeek" | "reverseMonths">,
+  props: Pick<
+    DayPickerProps,
+    "broadcastCalendar" | "fixedWeeks" | "ISOWeek" | "reverseMonths"
+  >,
   dateLib: DateLib
 ): CalendarMonth[] {
   const {
@@ -26,14 +33,17 @@ export function getMonths(
   } = dateLib;
   const dayPickerMonths = displayMonths.reduce<CalendarMonth[]>(
     (months, month) => {
-      const firstDateOfFirstWeek = props.ISOWeek
-        ? startOfISOWeek(month)
-        : startOfWeek(month);
-
-      const lastDateOfLastWeek = props.ISOWeek
-        ? endOfISOWeek(endOfMonth(month))
-        : endOfWeek(endOfMonth(month));
+      const firstDateOfFirstWeek = props.broadcastCalendar
+        ? startOfBroadcastWeek(month)
+        : props.ISOWeek
+          ? startOfISOWeek(month)
+          : startOfWeek(month);
 
+      const lastDateOfLastWeek = props.broadcastCalendar
+        ? endOfBroadcastWeek(month)
+        : props.ISOWeek
+          ? endOfISOWeek(endOfMonth(month))
+          : endOfWeek(endOfMonth(month));
       /** The dates to display in the month. */
       const monthDates = dates.filter((date) => {
         return date >= firstDateOfFirstWeek && date <= lastDateOfLastWeek;

src/types/props.ts

@@ -243,6 +243,14 @@ export interface PropsBase {
    * @see https://daypicker.dev/docs/customization#showweeknumber
    */
   showWeekNumber?: boolean;
+  /**
+   * Display the weeks in the month following the broadcast calendar. Setting
+   * this prop will ignore {@link weekStartsOn} and {@link fixedWeeks}.
+   *
+   * @see https://daypicker.dev/docs/customization#broadcast-calendar
+   * @see https://en.wikipedia.org/wiki/Broadcast_calendar
+   */
+  broadcastCalendar?: boolean;
   /**
    * Use ISO week dates instead of the locale setting. Setting this prop will
    * ignore `weekStartsOn` and `firstWeekContainsDate`.

src/useCalendar.ts

@@ -81,6 +81,7 @@ export function useCalendar(
     | "month"
     | "defaultMonth"
     | "timeZone"
+    | "broadcastCalendar"
     // Deprecated:
     | "fromMonth"
     | "fromYear"

website/docs/docs/localization.mdx

@@ -135,3 +135,28 @@ export function Jalali() {
 <BrowserWindow>
   <Examples.Jalali />
 </BrowserWindow>
+
+
+## Broadcast Calendar
+
+DayPicker supports the Broadcast Calendar. More Details in https://en.wikipedia.org/wiki/Broadcast_calendar
+
+:::warning Experimental Feature
+
+Support for the Broadcast calendar is an experimental feature. [Please report](https://github.com/gpbl/react-day-picker/issues) any issues you encounter. Thank you!
+
+:::
+
+```tsx title="./broadcastCalendar.jsx"
+import React from "react";
+
+import { DayPicker } from "react-day-picker";
+
+export default function App() {
+  return <DayPicker showOutsideDays showWeekNumber broadcastCalendar />;
+}
+```
+
+<BrowserWindow>
+  <Examples.BroadcastCalendar />
+</BrowserWindow>