Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 | 1x 1x 1x 1x 138x 138x 138x 138x 138x 42x 21x 138x 138x 45x 93x 138x 138x 45x 93x 138x 138x 138x | import { day, type DayOfWeek, daysPerWeek, month } from './date.ts';
import { isNumber } from './is-number.ts';
import { modulo } from './modulo.ts';
/**
* Options for the {@link isoWeeksInYear} function
* @group Time
* @category Week
*/
export type ISOWeeksInYearOptions = {
/** Use the utc timezone */
utc?: boolean;
/** Week 1 is defined as the week with the Gregorian year's first [weekOneIncludes] day in it */
weekOneIncludes?: DayOfWeek;
};
/**
* Determine the number of ISO weeks within a year
* @param input - A date within the year, or a year number
* @param options - see {@link ISOWeeksInYearOptions}
* @defaultValue weekOneIncludes Thursday
* @returns The number of weeks in the year (52 or 53)
* @group Time
* @category Week
*/
export function isoWeeksInYear(
input: Date | number,
{ utc = false, weekOneIncludes = day.thursday }: ISOWeeksInYearOptions = {},
): number {
const year =
isNumber(input) ? input
: utc ? input.getUTCFullYear()
: input.getFullYear();
const dow0 =
utc ?
new Date(Date.UTC(year, month.january, 1)).getUTCDay()
: new Date(year, month.january, 1).getDay();
const dow1 =
utc ?
new Date(Date.UTC(year, month.december, 31)).getUTCDay()
: new Date(year, month.december, 31).getDay();
const target = modulo(weekOneIncludes, daysPerWeek);
return dow0 === target || dow1 === target ? 53 : 52;
}
|