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Module

std/datetime/week_of_year.ts

Deno standard library
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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
import { DAY, WEEK } from "./constants.ts";
const DAYS_PER_WEEK = 7;
const Day = { Sun: 0, Mon: 1, Tue: 2, Wed: 3, Thu: 4, Fri: 5, Sat: 6,} as const;
/** * Returns the ISO week number of the provided date (1-53). * * @example * ```ts * import { weekOfYear } from "https://deno.land/std@$STD_VERSION/datetime/week_of_year.ts"; * * weekOfYear(new Date("2020-12-28T03:24:00")); // Returns 53 * ``` * * @return Number of the week in year */export function weekOfYear(date: Date): number { const workingDate = new Date( Date.UTC(date.getFullYear(), date.getMonth(), date.getDate()), );
const day = workingDate.getUTCDay();
const nearestThursday = workingDate.getUTCDate() + Day.Thu - (day === Day.Sun ? DAYS_PER_WEEK : day);
workingDate.setUTCDate(nearestThursday);
// Get first day of year const yearStart = new Date(Date.UTC(workingDate.getUTCFullYear(), 0, 1));
// return the calculated full weeks to nearest Thursday return Math.ceil((workingDate.getTime() - yearStart.getTime() + DAY) / WEEK);}