vremel/dist/datetime/startOfWeek.js

JavaScript date utility library for Temporal API

import { isPlainDate, isZonedDateTime } from "../type-utils.js";
import { startOfTimeForZonedDateTime } from "./_startOfTimeForZonedDateTime.js";
function startOfWeekWithDayPrecision(dt, firstDayOfWeek) {
    return dt.subtract({
        days: (dt.dayOfWeek - firstDayOfWeek + dt.daysInWeek) % dt.daysInWeek,
    });
}
/**
 * Returns the start of a week for the given datetime.
 * 'start of a week' is ambiguous and locale-dependent,
 * so `firstDayOfWeek` option is required.
 * This function supports a calendar with a fixed `daysInWeek`,
 * even if the week contains more or less than 7 days.
 * But it doesn't support a calendar which lacks a fixed number of days.
 *
 * @param dt datetime object which includes date info
 * @returns Temporal object which represents the start of a week
 */
export function startOfWeek(dt, options) {
    const firstDayOfWeek = options.firstDayOfWeek;
    if (!Number.isInteger(firstDayOfWeek) ||
        firstDayOfWeek < 1 ||
        firstDayOfWeek > dt.daysInWeek) {
        throw new Error(`${firstDayOfWeek} isn't a valid day of week`);
    }
    const timeArg = {
        hour: 0,
        minute: 0,
        second: 0,
        millisecond: 0,
        microsecond: 0,
        nanosecond: 0,
    };
    if (isZonedDateTime(dt)) {
        const startOfWeek = startOfWeekWithDayPrecision(dt.toPlainDate(), firstDayOfWeek);
        return startOfTimeForZonedDateTime(dt, {
            year: startOfWeek.year,
            month: startOfWeek.month,
            day: startOfWeek.day,
            ...timeArg,
        });
    }
    if (isPlainDate(dt)) {
        return startOfWeekWithDayPrecision(dt, firstDayOfWeek);
    }
    return startOfWeekWithDayPrecision(dt, firstDayOfWeek).with(timeArg);
}
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