Repository: date-fns/date-fns
File: src/getWeek/index.ts (TypeScript)

Code before:
import startOfWeek from '../startOfWeek/index'
import startOfWeekYear from '../startOfWeekYear/index'
import toDate from '../toDate/index'
import requiredArgs from '../_lib/requiredArgs/index'

const MILLISECONDS_IN_WEEK = 604800000

export interface GetWeekOptions {
  locale: Locale,
  weekStartsOn: 0 | 1 | 2 | 3 | 4 | 5 | 6,
  firstWeekContainsDate: 1 | 2 | 3 | 4 | 5 | 6 | 7,
}

/**
 * @name getWeek
 * @category Week Helpers
 * @summary Get the local week index of the given date.
 *
 * @description
 * Get the local week index of the given date.
 * The exact calculation depends on the values of
 * `options.weekStartsOn` (which is the index of the first day of the week)
 * and `options.firstWeekContainsDate` (which is the day of January, which is always in
 * the first week of the week-numbering year)
 *
 * Week numbering: https://en.wikipedia.org/wiki/Week#Week_numbering
 *
 * ### 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)
 * @param {1|2|3|4|5|6|7} [options.firstWeekContainsDate=1] - the day of January, which is always in the first week of the year

Review comment (suggestion):
Could you please use the existing types from [types.ts](https://github.com/date-fns/date-fns/blob/master/src/types.ts)

Code after:
import startOfWeek from '../startOfWeek/index'
import startOfWeekYear from '../startOfWeekYear/index'
import toDate from '../toDate/index'
import requiredArgs from '../_lib/requiredArgs/index'
import { LocaleOptions, WeekStartOptions, FirstWeekContainsDateOptions } from '../types'

const MILLISECONDS_IN_WEEK = 604800000

/**
 * @name getWeek
 * @category Week Helpers
 * @summary Get the local week index of the given date.
 *
 * @description
 * Get the local week index of the given date.
 * The exact calculation depends on the values of
 * `options.weekStartsOn` (which is the index of the first day of the week)
 * and `options.firstWeekContainsDate` (which is the day of January, which is always in
 * the first week of the week-numbering year)
 *
 * Week numbering: https://en.wikipedia.org/wiki/Week#Week_numbering
 *
 * ### 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)
 * @param {1|2|3|4|5|6|7} [options.firstWeekContainsDate=1] - the day of January, which is always in the first week of the year
 * @returns {Number} the week
 * @throws {TypeError} 1 argument required
 * @throws {RangeError} `options.weekStartsOn` must be between 0 and 6
 * @throws {RangeError} `options.firstWeekContainsDate` must be between 1 and 7
 *