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Module

std/datetime/mod.ts

Deno standard library
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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license./** * This module is browser compatible. * @module */
import { DateTimeFormatter } from "./formatter.ts";
export const SECOND = 1e3;export const MINUTE = SECOND * 60;export const HOUR = MINUTE * 60;export const DAY = HOUR * 24;export const WEEK = DAY * 7;const DAYS_PER_WEEK = 7;
enum Day { Sun, Mon, Tue, Wed, Thu, Fri, Sat,}
/** * Parse date from string using format string * @param dateString Date string * @param format Format string * @return Parsed date */export function parse(dateString: string, formatString: string): Date { const formatter = new DateTimeFormatter(formatString); const parts = formatter.parseToParts(dateString); const sortParts = formatter.sortDateTimeFormatPart(parts); return formatter.partsToDate(sortParts);}
/** * Format date using format string * @param date Date * @param format Format string * @return formatted date string */export function format(date: Date, formatString: string): string { const formatter = new DateTimeFormatter(formatString); return formatter.format(date);}
/** * Get number of the day in the year * @return Number of the day in year */export function dayOfYear(date: Date): number { // Values from 0 to 99 map to the years 1900 to 1999. All other values are the actual year. (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/Date) // Using setFullYear as a workaround
const yearStart = new Date(date);
yearStart.setUTCFullYear(date.getUTCFullYear(), 0, 0); const diff = date.getTime() - yearStart.getTime();
return Math.floor(diff / DAY);}/** * Get number of the week in the year (ISO-8601) * @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);}
/** * Parse a date to return a IMF formatted string date * RFC: https://tools.ietf.org/html/rfc7231#section-7.1.1.1 * IMF is the time format to use when generating times in HTTP * headers. The time being formatted must be in UTC for Format to * generate the correct format. * @param date Date to parse * @return IMF date formatted string */export function toIMF(date: Date): string { function dtPad(v: string, lPad = 2): string { return v.padStart(lPad, "0"); } const d = dtPad(date.getUTCDate().toString()); const h = dtPad(date.getUTCHours().toString()); const min = dtPad(date.getUTCMinutes().toString()); const s = dtPad(date.getUTCSeconds().toString()); const y = date.getUTCFullYear(); const days = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"]; const months = [ "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec", ]; return `${days[date.getUTCDay()]}, ${d} ${ months[date.getUTCMonth()] } ${y} ${h}:${min}:${s} GMT`;}
/** * Check given year is a leap year or not. * based on : https://docs.microsoft.com/en-us/office/troubleshoot/excel/determine-a-leap-year * @param year year in number or Date format */export function isLeap(year: Date | number): boolean { const yearNumber = year instanceof Date ? year.getFullYear() : year; return ( (yearNumber % 4 === 0 && yearNumber % 100 !== 0) || yearNumber % 400 === 0 );}
export type Unit = | "milliseconds" | "seconds" | "minutes" | "hours" | "days" | "weeks" | "months" | "quarters" | "years";
export type DifferenceFormat = Partial<Record<Unit, number>>;
export type DifferenceOptions = { units?: Unit[];};
/** * Calculate difference between two dates. * @param from Year to calculate difference * @param to Year to calculate difference with * @param options Options for determining how to respond * * example : * * ```typescript * import * as datetime from "./mod.ts"; * * datetime.difference(new Date("2020/1/1"),new Date("2020/2/2"),{ units : ["days","months"] }) * ``` */export function difference( from: Date, to: Date, options?: DifferenceOptions,): DifferenceFormat { const uniqueUnits = options?.units ? [...new Set(options?.units)] : [ "milliseconds", "seconds", "minutes", "hours", "days", "weeks", "months", "quarters", "years", ];
const bigger = Math.max(from.getTime(), to.getTime()); const smaller = Math.min(from.getTime(), to.getTime()); const differenceInMs = bigger - smaller;
const differences: DifferenceFormat = {};
for (const uniqueUnit of uniqueUnits) { switch (uniqueUnit) { case "milliseconds": differences.milliseconds = differenceInMs; break; case "seconds": differences.seconds = Math.floor(differenceInMs / SECOND); break; case "minutes": differences.minutes = Math.floor(differenceInMs / MINUTE); break; case "hours": differences.hours = Math.floor(differenceInMs / HOUR); break; case "days": differences.days = Math.floor(differenceInMs / DAY); break; case "weeks": differences.weeks = Math.floor(differenceInMs / WEEK); break; case "months": differences.months = calculateMonthsDifference(bigger, smaller); break; case "quarters": differences.quarters = Math.floor( (typeof differences.months !== "undefined" && differences.months / 4) || calculateMonthsDifference(bigger, smaller) / 4, ); break; case "years": differences.years = Math.floor( (typeof differences.months !== "undefined" && differences.months / 12) || calculateMonthsDifference(bigger, smaller) / 12, ); break; } }
return differences;}
function calculateMonthsDifference(bigger: number, smaller: number): number { const biggerDate = new Date(bigger); const smallerDate = new Date(smaller); const yearsDiff = biggerDate.getFullYear() - smallerDate.getFullYear(); const monthsDiff = biggerDate.getMonth() - smallerDate.getMonth(); const calendarDifferences = Math.abs(yearsDiff * 12 + monthsDiff); const compareResult = biggerDate > smallerDate ? 1 : -1; biggerDate.setMonth( biggerDate.getMonth() - compareResult * calendarDifferences, ); const isLastMonthNotFull = biggerDate > smallerDate ? 1 : -1 === -compareResult ? 1 : 0; const months = compareResult * (calendarDifferences - isLastMonthNotFull); return months === 0 ? 0 : months;}