Jak przekonwertować numer tygodnia na datę w JavaScript

Question

Próbowałem znaleźć pracę, ale nie miałem szczęścia. Jakieś pomysły?

Przykłady:

tydzień, 1, 2001 => 2001-01-01

Tydzień, 26, 2007 => 2007-06-01

Answer 1

Nie, nie ma funkcji dla tego . Musisz to zrobić ręcznie. Postępuj zgodnie z this way.

Answer 2

Spójrz na at this fiddle. Po pierwsze, dostaje pierwszy tydzień określonego roku. To bierze pod uwagę, że według ISO 8601 pierwszy tydzień roku to pierwszy tydzień zawierający środę. Następnie dodaje tygodnie do uzyskanej daty i zwraca wynik.

function firstDayOfWeek(week, year) { 

    var date  = firstWeekOfYear(year), 
     weekTime = weeksToMilliseconds(week), 
     targetTime = weekTime + date.getTime(); 

    return date.setTime(targetTime); 

} 

Answer 3

wziąłem oryginalny pomysł z Kevin, z pewnymi ulepszeniami, bo oryginalny kod wraca milisekund. Proszę bardzo:

var d = firstDayOfWeek(9, 2013); 

console.log(d.format("yyyy-MM-dd")); 

////////////////////////////// Main Code ////////////////////////////// 
function firstDayOfWeek(week, year) { 

    if (typeof year !== 'undefined') { 
     year = (new Date()).getFullYear(); 
    } 

    var date  = firstWeekOfYear(year), 
     weekTime = weeksToMilliseconds(week), 
     targetTime = date.getTime() + weekTime - 86400000; 

    var result = new Date(targetTime) 

    return result; 
} 

function weeksToMilliseconds(weeks) { 
    return 1000 * 60 * 60 * 24 * 7 * (weeks - 1); 
} 

function firstWeekOfYear(year) { 
    var date = new Date(); 
    date = firstDayOfYear(date,year); 
    date = firstWeekday(date); 
    return date; 
} 

function firstDayOfYear(date, year) { 
    date.setYear(year); 
    date.setDate(1); 
    date.setMonth(0); 
    date.setHours(0); 
    date.setMinutes(0); 
    date.setSeconds(0); 
    date.setMilliseconds(0); 
    return date; 
} 

function firstWeekday(date) { 

    var day = date.getDay(), 
     day = (day === 0) ? 7 : day; 

    if (day > 3) { 

     var remaining = 8 - day, 
      target = remaining + 1; 

     date.setDate(target); 
    } 

    return date; 
} 

Answer 4

Jako kod Kevina nie wdraża ISO 8601 prawidłowo (pierwszy dzień pierwszego tygodnia roku musi być poniedziałek), mam poprawione to i skończyło się (także check it on jsfiddle):

function firstDayOfWeek(week, year) { 

    if (year==null) { 
     year = (new Date()).getFullYear(); 
    } 

    var date  = firstWeekOfYear(year), 
     weekTime = weeksToMilliseconds(week), 
     targetTime = date.getTime() + weekTime; 

    return date.setTime(targetTime); 

} 

function weeksToMilliseconds(weeks) { 
    return 1000 * 60 * 60 * 24 * 7 * (weeks - 1); 
} 

function firstWeekOfYear(year) { 
    var date = new Date(); 
    date = firstDayOfYear(date,year); 
    date = firstWeekday(date); 
    return date; 
} 

function firstDayOfYear(date, year) { 
    date.setYear(year); 
    date.setDate(1); 
    date.setMonth(0); 
    date.setHours(0); 
    date.setMinutes(0); 
    date.setSeconds(0); 
    date.setMilliseconds(0); 
    return date; 
} 

/** 
* Sets the given date as the first day of week of the first week of year. 
*/ 
function firstWeekday(firstOfJanuaryDate) { 
    // 0 correspond au dimanche et 6 correspond au samedi. 
    var FIRST_DAY_OF_WEEK = 1; // Monday, according to iso8601 
    var WEEK_LENGTH = 7; // 7 days per week 
    var day = firstOfJanuaryDate.getDay(); 
    day = (day === 0) ? 7 : day; // make the days monday-sunday equals to 1-7 instead of 0-6 
    var dayOffset=-day+FIRST_DAY_OF_WEEK; // dayOffset will correct the date in order to get a Monday 
    if (WEEK_LENGTH-day+1<4) { 
     // the current week has not the minimum 4 days required by iso 8601 => add one week 
     dayOffset += WEEK_LENGTH; 
    } 
    return new Date(firstOfJanuaryDate.getTime()+dayOffset*24*60*60*1000); 
} 

function assertDateEquals(effectiveDate, expectedDate, description) { 
    if ((effectiveDate==null^expectedDate==null) || effectiveDate.getTime()!=expectedDate.getTime()) { 
     console.log("assert failed: "+description+"; effective="+effectiveDate+", expected="+expectedDate); 
    } 
} 
function assertEquals(effectiveValue, expectedValue, description) { 
    if (effectiveValue!=expectedValue) { 
     console.log("assert failed: "+description+"; effective="+effectiveValue+", expected="+expectedValue); 
    } 
} 

// expect the first day of year to be a monday 
for (var i=1970; i<2050; i++) { 
    assertEquals(firstWeekOfYear(i).getDay(), 1, "first day of year "+i+" must be a monday"); // 1=Monday 
} 

// assert some future first day of first week of year; source: http://www.epochconverter.com/date-and-time/weeknumbers-by-year.php 
assertDateEquals(firstWeekOfYear(2013), new Date(Date.parse("Dec 31, 2012")), "2013"); 
assertDateEquals(firstWeekOfYear(2014), new Date(Date.parse("Dec 30, 2013")), "2014"); 
assertDateEquals(firstWeekOfYear(2015), new Date(Date.parse("Dec 29, 2014")), "2015"); 
assertDateEquals(firstWeekOfYear(2016), new Date(Date.parse("Jan 4, 2016")), "2016"); 
assertDateEquals(firstWeekOfYear(2017), new Date(Date.parse("Jan 2, 2017")), "2017"); 
assertDateEquals(firstWeekOfYear(2018), new Date(Date.parse("Jan 1, 2018")), "2018"); 
assertDateEquals(firstWeekOfYear(2019), new Date(Date.parse("Dec 31, 2018")), "2019"); 
assertDateEquals(firstWeekOfYear(2020), new Date(Date.parse("Dec 30, 2019")), "2020"); 
assertDateEquals(firstWeekOfYear(2021), new Date(Date.parse("Jan 4, 2021")), "2021"); 
assertDateEquals(firstWeekOfYear(2022), new Date(Date.parse("Jan 3, 2022")), "2022"); 
assertDateEquals(firstWeekOfYear(2023), new Date(Date.parse("Jan 2, 2023")), "2023"); 
assertDateEquals(firstWeekOfYear(2024), new Date(Date.parse("Jan 1, 2024")), "2024"); 
assertDateEquals(firstWeekOfYear(2025), new Date(Date.parse("Dec 30, 2024")), "2025"); 
assertDateEquals(firstWeekOfYear(2026), new Date(Date.parse("Dec 29, 2025")), "2026"); 

console.log("All assertions done."); 

włączyłem przypadków testowych dla niektórych daty, aby sprawdzić, że pierwszy dzień pierwszego tygodnia roku jest poniedziałek i sprawdzone kilka dat w oparciu o http://www.epochconverter.com/date-and-time/weeknumbers-by-year.php

Answer 5

ktoś może być nadal zainteresowani bardziej zamkniętego wersji:

function firstDayOfWeek (year, week) { 

    // Jan 1 of 'year' 
    var d = new Date(year, 0, 1), 
     offset = d.getTimezoneOffset(); 

    // ISO: week 1 is the one with the year's first Thursday 
    // so nearest Thursday: current date + 4 - current day number 
    // Sunday is converted from 0 to 7 
    d.setDate(d.getDate() + 4 - (d.getDay() || 7)); 

    // 7 days * (week - overlapping first week) 
    d.setTime(d.getTime() + 7 * 24 * 60 * 60 * 1000 
     * (week + (year == d.getFullYear() ? -1 : 0))); 

    // daylight savings fix 
    d.setTime(d.getTime() 
     + (d.getTimezoneOffset() - offset) * 60 * 1000); 

    // back to Monday (from Thursday) 
    d.setDate(d.getDate() - 3); 

    return d; 
}