@progress/kendo-date-math/dist/es2015/first-day-in-week.js

Kendo UI typescript package exporting functions for Date manipulations

import { cloneDate } from './clone-date';
import { Day } from './day.enum';
/**
 *  A function which returns the first date of the current week.
 *
 * @param date - The initial date.
 * @param weekStartDay [default: Day.Sunday] - The first day of the week.
 * @returns - The first date of the current week.
 *
 * @example
 * ```ts-no-run
 * firstDayInWeek(new Date(2016, 0, 15)); // 2016-01-10
 * firstDayInWeek(new Date(2016, 0, 15), Day.Monday); // 2016-01-11
 * ```
 */
export const firstDayInWeek = (date, weekStartDay = Day.Sunday) => {
    const first = cloneDate(date);
    while (first.getDay() !== weekStartDay) {
        first.setDate(first.getDate() - 1);
    }
    return first;
};