/
index.ts
51 lines (49 loc) · 1.74 KB
/
index.ts
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import differenceInCalendarWeeks from '../differenceInCalendarWeeks/index'
import lastDayOfMonth from '../lastDayOfMonth/index'
import startOfMonth from '../startOfMonth/index'
import requiredArgs from '../_lib/requiredArgs/index'
import { LocaleOptions, WeekStartOptions } from '../types'
/**
* @name getWeeksInMonth
* @category Week Helpers
* @summary Get the number of calendar weeks a month spans.
*
* @description
* Get the number of calendar weeks the month in the given date spans.
*
* ### v2.0.0 breaking changes:
*
* - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
*
* @param {Date|Number} date - the given date
* @param {Object} [options] - an object with options.
* @param {Locale} [options.locale=defaultLocale] - the locale object. See [Locale]{@link https://date-fns.org/docs/Locale}
* @param {0|1|2|3|4|5|6} [options.weekStartsOn=0] - the index of the first day of the week (0 - Sunday)
* @returns {Number} the number of calendar weeks
* @throws {TypeError} 2 arguments required
* @throws {RangeError} `options.weekStartsOn` must be between 0 and 6
*
* @example
* // How many calendar weeks does February 2015 span?
* const result = getWeeksInMonth(new Date(2015, 1, 8))
* //=> 4
*
* @example
* // If the week starts on Monday,
* // how many calendar weeks does July 2017 span?
* const result = getWeeksInMonth(new Date(2017, 6, 5), { weekStartsOn: 1 })
* //=> 6
*/
export default function getWeeksInMonth(
date: Date | number,
options?: LocaleOptions & WeekStartOptions
): number {
requiredArgs(1, arguments)
return (
differenceInCalendarWeeks(
lastDayOfMonth(date),
startOfMonth(date),
options
) + 1
)
}