blocks|key|2964110|text|您还可以使用momentjs库：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2964111|moment().format('W')|offset|length|style|CODE|2964112|entityMap|0|LINK|mutability|MUTABLE|url|http://momentjs.com/docs/#/displaying/^0|0|0|K|0|K|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Q|8|@$D|R|E|S|F|G]]|9|@$D|T|E|U|1|V]]|A|$]]|$1|H|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|O]]]]

You can use momentjs library also:

<a href="http://momentjs.com/docs/#/displaying/" rel="noreferrer"><code>moment().format('W')</code></a>

blocks|key|267529|text|不是ISO-8601周的数字，但如果搜索引擎指出你在这里的话。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|267530|如上所述，但没有类：|267531|​|267532|let+now+=+new+Date();
let+onejan+=+new+Date(now.getFullYear(),+0,+1);
let+week+=+Math.ceil((((now.getTime()+-+onejan.getTime())+/+86400000)+%2B+onejan.getDay()+%2B+1)+/+7);

console.log(week);|code-block|syntax|javascript|267533|267534|entityMap^0|0|V|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|U|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|V|8|@]|D|@]|E|$]]|$1|J|3|K|5|L|7|W|8|@]|D|@]|E|$M|N]]|$1|O|3|I|5|6|7|X|8|@]|D|@]|E|$]]|$1|P|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|Q|$]]

Not ISO-8601 week number but if the search engine pointed you here anyways.
As said above but without a class:
<div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>let now = new Date();
let onejan = new Date(now.getFullYear(), 0, 1);
let week = Math.ceil((((now.getTime() - onejan.getTime()) / 86400000) + onejan.getDay() + 1) / 7);

console.log(week);</code></pre>
</div>
</div>

blocks|key|3177763|text|因此，http://javascript.about.com/library/blweekyear.htm|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3177764|Date.prototype.getWeek+=+function()+{
++++var+onejan+=+new+Date(this.getFullYear(),0,1);
++++var+millisecsInDay+=+86400000;
++++return+Math.ceil((((this+-+onejan)+/millisecsInDay)+%2B+onejan.getDay()%2B1)/7);
};|code-block|syntax|javascript|3177765|entityMap|0|LINK|mutability|MUTABLE|url|http://javascript.about.com/library/blweekyear.htm^0|3|1E|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Accordily <a href="http://javascript.about.com/library/blweekyear.htm">http://javascript.about.com/library/blweekyear.htm</a>

<pre><code>Date.prototype.getWeek = function() {
 var onejan = new Date(this.getFullYear(),0,1);
 var millisecsInDay = 86400000;
 return Math.ceil((((this - onejan) /millisecsInDay) + onejan.getDay()+1)/7);
};
</code></pre>

blocks|key|2963969|text|Jacob+Wright的Date.format()库实现了date()函数风格的日期格式化，并支持ISO8601Week+number：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2963970|new+Date().format('W');|code-block|syntax|javascript|2963971|对于只有一周的数字来说，它可能有点夸张，但它确实支持PHP样式格式，如果你要做很多这样的事情，它会非常方便。|2963972|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/jacwright/date.format|1|http://www.php.net/manual/en/function.date.php^0|D|D|U|6|D|D|0|U|6|1|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@$9|11|A|12|1|13]|$9|14|A|15|1|16]]|E|$]]|$1|F|3|G|5|H|7|17|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|18|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]|U|$5|P|Q|R|E|$S|V]]]]

Jacob Wright's <a href="https://github.com/jacwright/date.format"><code>Date.format()</code></a> library implements date formatting in the style of PHP's <a href="http://www.php.net/manual/en/function.date.php"><code>date()</code></a> function and supports the ISO-8601 week number:

<pre><code>new Date().format('W');
</code></pre>

It may be a bit overkill for just a week number, but it does support PHP style formatting and is quite handy if you'll be doing a lot of this.

blocks|key|3177817|text|获取任意给定日期的周编号|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3177818|function+week(year,month,day)+{
++++function+serial(days)+{+return+86400000*days;+}
++++function+dateserial(year,month,day)+{+return+(new+Date(year,month-1,day).valueOf());+}
++++function+weekday(date)+{+return+(new+Date(date)).getDay()%2B1;+}
++++function+yearserial(date)+{+return+(new+Date(date)).getFullYear();+}
++++var+date+=+year+instanceof+Date+?+year.valueOf()+:+typeof+year+===+"string"+?+new+Date(year).valueOf()+:+dateserial(year,month,day),+
++++++++date2+=+dateserial(yearserial(date+-+serial(weekday(date-serial(1)))+%2B+serial(4)),1,3);
++++return+~~((date+-+date2+%2B+serial(weekday(date2)+%2B+5))/+serial(7));
}|code-block|syntax|javascript|3177819|示例|3177820|console.log(
++++week(2016,+06,+11),//23
++++week(2015,+9,+26),//39
++++week(2016,+1,+1),//53
++++week(2016,+1,+4),//1
++++week(new+Date(2016,+0,+4)),//1
++++week("11+january+2016")//2
);|3177821|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Get the weeknumber of any given Date

<pre><code>function week(year,month,day) {
 function serial(days) { return 86400000*days; }
 function dateserial(year,month,day) { return (new Date(year,month-1,day).valueOf()); }
 function weekday(date) { return (new Date(date)).getDay()+1; }
 function yearserial(date) { return (new Date(date)).getFullYear(); }
 var date = year instanceof Date ? year.valueOf() : typeof year === "string" ? new Date(year).valueOf() : dateserial(year,month,day), 
 date2 = dateserial(yearserial(date - serial(weekday(date-serial(1))) + serial(4)),1,3);
 return ~~((date - date2 + serial(weekday(date2) + 5))/ serial(7));
}
</code></pre>

<h2>Example</h2>

<pre><code>console.log(
 week(2016, 06, 11),//23
 week(2015, 9, 26),//39
 week(2016, 1, 1),//53
 week(2016, 1, 4),//1
 week(new Date(2016, 0, 4)),//1
 week("11 january 2016")//2
);
</code></pre>

blocks|key|2964135|text|下面的代码计算出正确的ISO+8601周数。它匹配PHP1970年1月1日到2100年1月1日之间每周的date("W")。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2964136|/**
+*+Get+the+ISO+week+date+week+number
+*/
Date.prototype.getWeek+=+function+()+{
++//+Create+a+copy+of+this+date+object
++var+target+=+new+Date(this.valueOf());

++//+ISO+week+date+weeks+start+on+Monday,+so+correct+the+day+number
++var+dayNr+=+(this.getDay()+%2B+6)+%25+7;

++//+ISO+8601+states+that+week+1+is+the+week+with+the+first+Thursday+of+that+year
++//+Set+the+target+date+to+the+Thursday+in+the+target+week
++target.setDate(target.getDate()+-+dayNr+%2B+3);

++//+Store+the+millisecond+value+of+the+target+date
++var+firstThursday+=+target.valueOf();

++//+Set+the+target+to+the+first+Thursday+of+the+year
++//+First,+set+the+target+to+January+1st
++target.setMonth(0,+1);

++//+Not+a+Thursday?+Correct+the+date+to+the+next+Thursday
++if+(target.getDay()+!==+4)+{
++++target.setMonth(0,+1+%2B+((4+-+target.getDay())+%2B+7)+%25+7);
++}

++//+The+week+number+is+the+number+of+weeks+between+the+first+Thursday+of+the+year
++//+and+the+Thursday+in+the+target+week+(604800000+=+7+*+24+*+3600+*+1000)
++return+1+%2B+Math.ceil((firstThursday+-+target)+/+604800000);
}|code-block|syntax|javascript|2964137|来源：+Taco+van+den+Broek|BOLD|2964138|2964139|如果你对扩展原型不感兴趣，那么这里有一个函数：|2964140|function+getWeek(date)+{
++if+(!(date+instanceof+Date))+date+=+new+Date();

++//+ISO+week+date+weeks+start+on+Monday,+so+correct+the+day+number
++var+nDay+=+(date.getDay()+%2B+6)+%25+7;

++//+ISO+8601+states+that+week+1+is+the+week+with+the+first+Thursday+of+that+year
++//+Set+the+target+date+to+the+Thursday+in+the+target+week
++date.setDate(date.getDate()+-+nDay+%2B+3);

++//+Store+the+millisecond+value+of+the+target+date
++var+n1stThursday+=+date.valueOf();

++//+Set+the+target+to+the+first+Thursday+of+the+year
++//+First,+set+the+target+to+January+1st
++date.setMonth(0,+1);

++//+Not+a+Thursday?+Correct+the+date+to+the+next+Thursday
++if+(date.getDay()+!==+4)+{
++++date.setMonth(0,+1+%2B+((4+-+date.getDay())+%2B+7)+%25+7);
++}

++//+The+week+number+is+the+number+of+weeks+between+the+first+Thursday+of+the+year
++//+and+the+Thursday+in+the+target+week+(604800000+=+7+*+24+*+3600+*+1000)
++return+1+%2B+Math.ceil((n1stThursday+-+date)+/+604800000);
}|2964141|示例用法：|2964142|getWeek();+//+Returns+37+(or+whatever+the+current+week+is)
getWeek(new+Date('Jan+2,+2011'));+//+Returns+52
getWeek(new+Date('Jan+1,+2016'));+//+Returns+53
getWeek(new+Date('Jan+4,+2016'));+//+Returns+1|2964143|entityMap|0|LINK|mutability|MUTABLE|url|http://techblog.procurios.nl/k/news/view/33796/14863/calculate-iso-8601-week-and-year-in-javascript.html^0|1G|9|0|0|0|3|4|I|0|0|0|0|0|0|5|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|17|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|18|8|@$9|19|A|1A|B|M]]|D|@$9|1B|A|1C|1|1D]]|E|$]]|$1|N|3|-4|5|6|7|1E|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|1F|8|@]|D|@]|E|$]]|$1|Q|3|R|5|H|7|1G|8|@]|D|@]|E|$I|J]]|$1|S|3|T|5|6|7|1H|8|@$9|1I|A|1J|B|M]]|D|@]|E|$]]|$1|U|3|V|5|H|7|1K|8|@]|D|@]|E|$I|J]]|$1|W|3|-4|5|6|7|1L|8|@]|D|@]|E|$]]]|X|$Y|$5|Z|10|11|E|$12|13]]]]

The code below calculates the correct ISO 8601 week number. It matches PHP's <code>date("W")</code> for every week between 1/1/1970 and 1/1/2100.

<pre><code>/**
 * Get the ISO week date week number
 */
Date.prototype.getWeek = function () {
 // Create a copy of this date object
 var target = new Date(this.valueOf());

 // ISO week date weeks start on Monday, so correct the day number
 var dayNr = (this.getDay() + 6) % 7;

 // ISO 8601 states that week 1 is the week with the first Thursday of that year
 // Set the target date to the Thursday in the target week
 target.setDate(target.getDate() - dayNr + 3);

 // Store the millisecond value of the target date
 var firstThursday = target.valueOf();

 // Set the target to the first Thursday of the year
 // First, set the target to January 1st
 target.setMonth(0, 1);

 // Not a Thursday? Correct the date to the next Thursday
 if (target.getDay() !== 4) {
 target.setMonth(0, 1 + ((4 - target.getDay()) + 7) % 7);
 }

 // The week number is the number of weeks between the first Thursday of the year
 // and the Thursday in the target week (604800000 = 7 * 24 * 3600 * 1000)
 return 1 + Math.ceil((firstThursday - target) / 604800000);
}
</code></pre>

Source: <a href="http://techblog.procurios.nl/k/news/view/33796/14863/calculate-iso-8601-week-and-year-in-javascript.html" rel="noreferrer">Taco van den Broek</a>

<hr>

If you're not into extending prototypes, then here's a function:

<pre><code>function getWeek(date) {
 if (!(date instanceof Date)) date = new Date();

 // ISO week date weeks start on Monday, so correct the day number
 var nDay = (date.getDay() + 6) % 7;

 // ISO 8601 states that week 1 is the week with the first Thursday of that year
 // Set the target date to the Thursday in the target week
 date.setDate(date.getDate() - nDay + 3);

 // Store the millisecond value of the target date
 var n1stThursday = date.valueOf();

 // Set the target to the first Thursday of the year
 // First, set the target to January 1st
 date.setMonth(0, 1);

 // Not a Thursday? Correct the date to the next Thursday
 if (date.getDay() !== 4) {
 date.setMonth(0, 1 + ((4 - date.getDay()) + 7) % 7);
 }

 // The week number is the number of weeks between the first Thursday of the year
 // and the Thursday in the target week (604800000 = 7 * 24 * 3600 * 1000)
 return 1 + Math.ceil((n1stThursday - date) / 604800000);
}
</code></pre>

Sample usage:

<pre><code>getWeek(); // Returns 37 (or whatever the current week is)
getWeek(new Date('Jan 2, 2011')); // Returns 52
getWeek(new Date('Jan 1, 2016')); // Returns 53
getWeek(new Date('Jan 4, 2016')); // Returns 1
</code></pre>

blocks|key|2964096|text|getWeekOfYear:+function(date)+{
++++++++var+target+=+new+Date(date.valueOf()),
++++++++++++dayNumber+=+(date.getUTCDay()+%2B+6)+%25+7,
++++++++++++firstThursday;

++++++++target.setUTCDate(target.getUTCDate()+-+dayNumber+%2B+3);
++++++++firstThursday+=+target.valueOf();
++++++++target.setUTCMonth(0,+1);

++++++++if+(target.getUTCDay()+!==+4)+{
++++++++++++target.setUTCMonth(0,+1+%2B+((4+-+target.getUTCDay())+%2B+7)+%25+7);
++++++++}

++++++++return+Math.ceil((firstThursday+-+target)+/++(7+*+24+*+3600+*+1000))+%2B+1;
++++}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|2964097|以下代码与时区无关(使用协调世界时的日期)，并根据https://en.wikipedia.org/wiki/ISO_8601工作|unstyled|offset|length|2964098|entityMap|0|LINK|mutability|MUTABLE|url|https://en.wikipedia.org/wiki/ISO_8601^0|0|P|12|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|R|8|@]|9|@$G|S|H|T|1|U]]|A|$]]|$1|I|3|-4|5|F|7|V|8|@]|9|@]|A|$]]]|J|$K|$5|L|M|N|A|$O|P]]]]

<pre><code>getWeekOfYear: function(date) {
 var target = new Date(date.valueOf()),
 dayNumber = (date.getUTCDay() + 6) % 7,
 firstThursday;

 target.setUTCDate(target.getUTCDate() - dayNumber + 3);
 firstThursday = target.valueOf();
 target.setUTCMonth(0, 1);

 if (target.getUTCDay() !== 4) {
 target.setUTCMonth(0, 1 + ((4 - target.getUTCDay()) + 7) % 7);
 }

 return Math.ceil((firstThursday - target) / (7 * 24 * 3600 * 1000)) + 1;
 }
</code></pre>

Following code is timezone-independent (UTC dates used) and works according to the <a href="https://en.wikipedia.org/wiki/ISO_8601" rel="noreferrer">https://en.wikipedia.org/wiki/ISO_8601</a>

blocks|key|2963948|text|我发现在Oracle的规范http://goo.gl/7MbCh5上描述的Java的SimpleDateFormat类很有用。在我的例子中，在Google+Apps脚本中，它是这样工作的：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2963949|function+getWeekNumber()+{
++var+weekNum+=+parseInt(Utilities.formatDate(new+Date(),+"GMT",+"w"));
++Logger.log(weekNum);
}|code-block|syntax|javascript|2963950|例如，在电子表格宏中，您可以检索文件的实际时区：|2963951|function+getWeekNumber()+{
++var+weekNum+=+parseInt(Utilities.formatDate(new+Date(),+SpreadsheetApp.getActiveSpreadsheet().getSpreadsheetTimeZone(),+"w"));
++Logger.log(weekNum);
}|2963952|entityMap|0|LINK|mutability|MUTABLE|url|http://goo.gl/7MbCh5^0|D|K|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

I found useful the Java SE's SimpleDateFormat class described on Oracle's specification:
<a href="http://goo.gl/7MbCh5" rel="nofollow">http://goo.gl/7MbCh5</a>. In my case in Google Apps Script it worked like this:

<pre><code>function getWeekNumber() {
 var weekNum = parseInt(Utilities.formatDate(new Date(), "GMT", "w"));
 Logger.log(weekNum);
}
</code></pre>

For example in a spreadsheet macro you can retrieve the actual timezone of the file:

<pre><code>function getWeekNumber() {
 var weekNum = parseInt(Utilities.formatDate(new Date(), SpreadsheetApp.getActiveSpreadsheet().getSpreadsheetTimeZone(), "w"));
 Logger.log(weekNum);
}
</code></pre>

blocks|key|270838|text|这将在Date.prototype中添加"getWeek“方法，该方法返回年初以来的周数。该参数定义应考虑一周中的哪一天。如果没有通过任何参数，则假定周日是第一天。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|270839|/**
+*+Get+week+number+in+the+year.
+*+@param++{Integer}+[weekStart=0]++First+day+of+the+week.+0-based.+0+for+Sunday,+6+for+Saturday.
+*+@return+{Integer}++++++++++++++++0-based+number+of+week.
+*/
Date.prototype.getWeek+=+function(weekStart)+{
++++var+januaryFirst+=+new+Date(this.getFullYear(),+0,+1);
++++if(weekStart+!==+undefined+&&+(typeof+weekStart+!==+'number'+%7C%7C+weekStart+%25+1+!==+0+%7C%7C+weekStart+<+0+%7C%7C+weekStart+>+6))+{
++++++throw+new+Error('Wrong+argument.+Must+be+an+integer+between+0+and+6.');
++++}
++++weekStart+=+weekStart+%7C%7C+0;
++++return+Math.floor((((this+-+januaryFirst)+/+86400000)+%2B+januaryFirst.getDay()+-+weekStart)+/+7);
};|code-block|syntax|javascript|270840|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This adds "getWeek" method to Date.prototype which returns number of week from the beginning of the year. The argument defines which day of the week to consider the first. If no argument passed, first day is assumed Sunday.

<pre><code>/**
 * Get week number in the year.
 * @param {Integer} [weekStart=0] First day of the week. 0-based. 0 for Sunday, 6 for Saturday.
 * @return {Integer} 0-based number of week.
 */
Date.prototype.getWeek = function(weekStart) {
 var januaryFirst = new Date(this.getFullYear(), 0, 1);
 if(weekStart !== undefined &amp;&amp; (typeof weekStart !== 'number' || weekStart % 1 !== 0 || weekStart &lt; 0 || weekStart &gt; 6)) {
 throw new Error('Wrong argument. Must be an integer between 0 and 6.');
 }
 weekStart = weekStart || 0;
 return Math.floor((((this - januaryFirst) / 86400000) + januaryFirst.getDay() - weekStart) / 7);
};
</code></pre>

blocks|key|2964121|text|如果你已经在一个Angular项目中，你可以使用$filter('date')。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2964122|例如：|2964123|var+myDate+=+new+Date();
var+myWeek+=+$filter('date')(myDate,+'ww');|code-block|syntax|javascript|2964124|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.angularjs.org/api/ng/filter/date^0|O|F|O|F|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@$9|X|A|Y|1|Z]]|E|$]]|$1|F|3|G|5|6|7|10|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|11|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

If you are already in an Angular project you could use <a href="https://docs.angularjs.org/api/ng/filter/date" rel="nofollow"><code>$filter('date')</code></a>.

For example:

<pre><code>var myDate = new Date();
var myWeek = $filter('date')(myDate, 'ww');
</code></pre>

blocks|key|269035|text|对我来说效果很好的代码片段是这样的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|269036|var+yearStart+=+%2Bnew+Date(d.getFullYear(),+0,+1);
var+today+=+%2Bnew+Date(d.getFullYear(),d.getMonth(),d.getDate());
var+dayOfYear+=+((today+-+yearStart+%2B+1)+/+86400000);
return+Math.ceil(dayOfYear+/+7).toString();|code-block|syntax|javascript|269037|注意：|269038|d是我想要当前周数字的日期。|offset|length|style|CODE|269039|%2B将日期转换为数字(使用TypeScript)。|269040|entityMap^0|0|0|0|0|1|0|0|1|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|V|8|@$K|W|L|X|M|N]]|9|@]|A|$]]|$1|O|3|P|5|6|7|Y|8|@$K|Z|L|10|M|N]]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|R|$]]

The code snippet which works pretty well for me is this one:

<pre><code>var yearStart = +new Date(d.getFullYear(), 0, 1);
var today = +new Date(d.getFullYear(),d.getMonth(),d.getDate());
var dayOfYear = ((today - yearStart + 1) / 86400000);
return Math.ceil(dayOfYear / 7).toString();
</code></pre>

Note: 
<code>d</code> is my Date for which I want the current week number. 
The <code>+</code> converts the Dates into numbers (working with TypeScript).

blocks|key|2964292|text|使用Luxon+(https://github.com/moment/luxon)：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2964293|import+{+DateTime+}+from+'luxon';
const+week:+number+=+DateTime.fromJSDate(new+Date()).weekNumber;|code-block|syntax|javascript|2964294|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/moment/luxon^0|9|V|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

With Luxon (<a href="https://github.com/moment/luxon" rel="nofollow noreferrer">https://github.com/moment/luxon</a>) : 

<pre class="lang-js prettyprint-override"><code>import { DateTime } from 'luxon';
const week: number = DateTime.fromJSDate(new Date()).weekNumber;
</code></pre>

blocks|key|2964158|text|这周的数字是一个真正的痛苦在a**。网上的大多数脚本对我来说都不起作用。他们大部分时间都在工作，但他们都在某些时候崩溃了，特别是当年份发生变化，一年的最后一周突然变成了下一年的第一周等等。甚至angular的日期过滤器也显示了错误的数据(这是明年的第一周，angular给出了第53周)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2964159|注意：示例是为欧洲周(Mon+first)而设计的！|offset|length|style|BOLD|2964160|getWeek()|2964161|Date.prototype.getWeek+=+function(){

++++//+current+week's+Thursday
++++var+curWeek+=+new+Date(this.getTime());
++++++++curWeek.setDay(4);

++++//+Get+year's+first+week's+Thursday
++++var+firstWeek+=+new+Date(curWeek.getFullYear(),+0,+4);
++++++++firstWeek.setDay(4);

++++return+(curWeek.getDayIndex()+-+firstWeek.getDayIndex())+/+7+%2B+1;
};|code-block|syntax|javascript|2964162|setDay()|2964163|/**
*+Make+a+setDay()+prototype+for+Date
*+Sets+week+day+for+the+date
*/
Date.prototype.setDay+=+function(day){

++++//+Get+day+and+make+Sunday+to+7
++++var+weekDay+=+this.getDay()+%7C%7C+7;
++++var+distance+=+day+-+weekDay;
++++this.setDate(this.getDate()+%2B+distance);

++++return+this;
}|2964164|getDayIndex()|2964165|/*
*+Returns+index+of+given+date+(from+Jan+1st)
*/

Date.prototype.getDayIndex+=+function(){
++++var+start+=+new+Date(this.getFullYear(),+0,+0);
++++var+diff+=+this+-+start;
++++var+oneDay+=+86400000;

++++return+Math.floor(diff+/+oneDay);
};|2964166|我已经测试过了，它似乎工作得很好，但如果你注意到其中的一个缺陷，请让我知道。|2964167|entityMap^0|0|0|3|0|0|9|0|0|0|8|0|0|0|D|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@$D|12|E|13|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|14|8|@$D|15|E|16|F|G]]|9|@]|A|$]]|$1|J|3|K|5|L|7|17|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|18|8|@$D|19|E|1A|F|G]]|9|@]|A|$]]|$1|Q|3|R|5|L|7|1B|8|@]|9|@]|A|$M|N]]|$1|S|3|T|5|6|7|1C|8|@$D|1D|E|1E|F|G]]|9|@]|A|$]]|$1|U|3|V|5|L|7|1F|8|@]|9|@]|A|$M|N]]|$1|W|3|X|5|6|7|1G|8|@]|9|@]|A|$]]|$1|Y|3|-4|5|6|7|1H|8|@]|9|@]|A|$]]]|Z|$]]

This week number thing has been a real pain in the a**. Most of scripts around the net didn't work for me. They worked most of time but all of them broke in some point, especially when year changed and last week of the year was suddenly next year's first week etc. Even Angular's date filter showed incorrect data (it was 1st week of next year, angular gave week 53).

Note: Examples are designed to work with European weeks (Mon first)!

getWeek()

<pre><code>Date.prototype.getWeek = function(){

 // current week's Thursday
 var curWeek = new Date(this.getTime());
 curWeek.setDay(4);

 // Get year's first week's Thursday
 var firstWeek = new Date(curWeek.getFullYear(), 0, 4);
 firstWeek.setDay(4);

 return (curWeek.getDayIndex() - firstWeek.getDayIndex()) / 7 + 1;
};
</code></pre>

setDay()

<pre><code>/**
* Make a setDay() prototype for Date
* Sets week day for the date
*/
Date.prototype.setDay = function(day){

 // Get day and make Sunday to 7
 var weekDay = this.getDay() || 7;
 var distance = day - weekDay;
 this.setDate(this.getDate() + distance);

 return this;
}
</code></pre>

getDayIndex()

<pre><code>/*
* Returns index of given date (from Jan 1st)
*/

Date.prototype.getDayIndex = function(){
 var start = new Date(this.getFullYear(), 0, 0);
 var diff = this - start;
 var oneDay = 86400000;

 return Math.floor(diff / oneDay);
};
</code></pre>

I have tested this and it seems to be working very well but if you notice a flaw in it, please let me know.

blocks|key|2964207|text|下面是我在JavaScript中计算周数的实现。还更正了夏季和冬季的时间偏移。我使用了本文中对周的定义：ISO+8601|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2964208|星期是从星期一到星期日，1月4日总是在一年的第一周。|2964209|//+add+get+week+prototype+functions
//+weeks+always+start+from+monday+to+sunday
//+january+4th+is+always+in+the+first+week+of+the+year
Date.prototype.getWeek+=+function+()+{
++++year+=+this.getFullYear();
++++var+currentDotw+=+this.getWeekDay();
++++if+(this.getMonth()+==+11+&&+this.getDate()+-+currentDotw+>+28)+{
++++++++//+if+true,+the+week+is+part+of+next+year+
++++++++return+this.getWeekForYear(year+%2B+1);
++++}
++++if+(this.getMonth()+==+0+&&+this.getDate()+%2B+6+-+currentDotw+<+4)+{
++++++++//+if+true,+the+week+is+part+of+previous+year
++++++++return+this.getWeekForYear(year+-+1);
++++}
++++return+this.getWeekForYear(year);
}

//+returns+a+zero+based+day,+where+monday+=+0
//+all+weeks+start+with+monday
Date.prototype.getWeekDay+=+function+()+{
++++return++(this.getDay()+%2B+6)+%25+7;
}

//+corrected+for+summer/winter+time
Date.prototype.getWeekForYear+=+function+(year)+{
++++var+currentDotw+=+this.getWeekDay();
++++var+fourjan+=+new+Date(year,+0,+4);
++++var+firstDotw+=+fourjan.getWeekDay();
++++var+dayTotal+=+this.getDaysDifferenceCorrected(fourjan)+//+the+difference+in+days+between+the+two+dates.
++++//+correct+for+the+days+of+the+week
++++dayTotal+%2B=+firstDotw;+//+the+difference+between+the+current+date+and+the+first+monday+of+the+first+week,+
++++dayTotal+-=+currentDotw;+//+the+difference+between+the+first+monday+and+the+current+week's+monday
++++//+day+total+should+be+a+multiple+of+7+now
++++var+weeknumber+=+dayTotal+/+7+%2B+1;+//+add+one+since+it+gives+a+zero+based+week+number.
++++return+weeknumber;
}

//+corrected+for+timezones+and+offset
Date.prototype.getDaysDifferenceCorrected+=+function+(other)+{
++++var+millisecondsDifference+=+(this+-+other);
++++//+correct+for+offset+difference.+offsets+are+in+minutes,+the+difference+is+in+milliseconds
++++millisecondsDifference+%2B=+(other.getTimezoneOffset()-+this.getTimezoneOffset())+*+60000;
++++//+return+day+total.+1+day+is+86400000+milliseconds,+floor+the+value+to+return+only+full+days
++++return+Math.floor(millisecondsDifference+/+86400000);
}|code-block|syntax|javascript|2964210|为了进行测试，我在Qunit中使用了以下JavaScript测试|2964211|var+runweekcompare+=+function(result,+expected)+{
++++equal(result,+expected,'Week+nr+expected+value:+'+%2B+expected+%2B+'+Actual+value:+'+%2B+result);
}

test('first+week+number+test',+function+()+{
++++expect(5);
++++var+temp+=+new+Date(2016,+0,+4);+//+is+the+monday+of+the+first+week+of+the+year
++++runweekcompare(temp.getWeek(),+1);
++++var+temp+=+new+Date(2016,+0,+4,+23,+50);+//+is+the+monday+of+the+first+week+of+the+year
++++runweekcompare(temp.getWeek(),+1);
++++var+temp+=+new+Date(2016,+0,+10,+23,+50);+//+is+the+sunday+of+the+first+week+of+the+year
++++runweekcompare(temp.getWeek(),+1);
++++var+temp+=+new+Date(2016,+0,+11,+23,+50);+//+is+the+second+week+of+the+year
++++runweekcompare(temp.getWeek(),+2);
++++var+temp+=+new+Date(2016,+1,+29,+23,+50);+//+is+the+9th+week+of+the+year
++++runweekcompare(temp.getWeek(),+9);
});

test('first+day+is+part+of+last+years+last+week',+function+()+{
++++expect(2);
++++var+temp+=+new+Date(2016,+0,+1,+23,+50);+//+is+the+first+last+week+of+the+previous+year
++++runweekcompare(temp.getWeek(),+53);
++++var+temp+=+new+Date(2011,+0,+2,+23,+50);+//+is+the+first+last+week+of+the+previous+year
++++runweekcompare(temp.getWeek(),+52);
});

test('last++day+is+part+of+next+years+first+week',+function+()+{
++++var+temp+=+new+Date(2013,+11,+30);+//+is+part+of+the+first+week+of+2014
++++runweekcompare(temp.getWeek(),+1);
});

test('summer+winter+time+change',+function+()+{
++++expect(2);
++++var+temp+=+new+Date(2000,+2,+26);+
++++runweekcompare(temp.getWeek(),+12);
++++var+temp+=+new+Date(2000,+2,+27);+
++++runweekcompare(temp.getWeek(),+13);
});

test('full+20+year+test',+function+()+{
++++//expect(20+*+12+*+28+*+2);
++++for+(i+=+2000;+i+<+2020;+i%2B%2B)+{
++++++++for+(month+=+0;+month+<+12;+month%2B%2B)+{
++++++++++++for+(day+=+1;+day+<+29+;+day%2B%2B)+{
++++++++++++++++var+temp+=+new+Date(i,+month,+day);
++++++++++++++++var+expectedweek+=+temp.getWeek();
++++++++++++++++var+temp2+=+new+Date(i,+month,+day,+23,+50);
++++++++++++++++var+resultweek+=+temp.getWeek();
++++++++++++++++equal(expectedweek,+Math.round(expectedweek),+'week+number+whole+number+expected+'+%2B+Math.round(expectedweek)+%2B+'+resulted+week+nr+'+%2B+expectedweek);
++++++++++++++++equal(resultweek,+expectedweek,+'Week+nr+expected+value:+'+%2B+expectedweek+%2B+'+Actual+value:+'+%2B+resultweek+%2B+'+for+year+'+%2B+i+%2B+'+month+'+%2B+month+%2B+'+day+'+%2B+day);
++++++++++++}
++++++++}
++++}
});|2964212|entityMap|0|LINK|mutability|MUTABLE|url|https://en.wikipedia.org/wiki/ISO_8601^0|1G|8|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@$A|X|B|Y|1|Z]]|C|$]]|$1|D|3|E|5|6|7|10|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|11|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|12|8|@]|9|@]|C|$]]|$1|M|3|N|5|H|7|13|8|@]|9|@]|C|$I|J]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]]]

Here is my implementation for calculating the week number in JavaScript. corrected for summer and winter time offsets as well. 
I used the definition of the week from this article: <a href="https://en.wikipedia.org/wiki/ISO_8601" rel="nofollow noreferrer">ISO 8601</a>

Weeks are from mondays to sunday, and january 4th is always in the first week of the year.

<pre><code>// add get week prototype functions
// weeks always start from monday to sunday
// january 4th is always in the first week of the year
Date.prototype.getWeek = function () {
 year = this.getFullYear();
 var currentDotw = this.getWeekDay();
 if (this.getMonth() == 11 &amp;&amp; this.getDate() - currentDotw &gt; 28) {
 // if true, the week is part of next year 
 return this.getWeekForYear(year + 1);
 }
 if (this.getMonth() == 0 &amp;&amp; this.getDate() + 6 - currentDotw &lt; 4) {
 // if true, the week is part of previous year
 return this.getWeekForYear(year - 1);
 }
 return this.getWeekForYear(year);
}

// returns a zero based day, where monday = 0
// all weeks start with monday
Date.prototype.getWeekDay = function () {
 return (this.getDay() + 6) % 7;
}

// corrected for summer/winter time
Date.prototype.getWeekForYear = function (year) {
 var currentDotw = this.getWeekDay();
 var fourjan = new Date(year, 0, 4);
 var firstDotw = fourjan.getWeekDay();
 var dayTotal = this.getDaysDifferenceCorrected(fourjan) // the difference in days between the two dates.
 // correct for the days of the week
 dayTotal += firstDotw; // the difference between the current date and the first monday of the first week, 
 dayTotal -= currentDotw; // the difference between the first monday and the current week's monday
 // day total should be a multiple of 7 now
 var weeknumber = dayTotal / 7 + 1; // add one since it gives a zero based week number.
 return weeknumber;
}

// corrected for timezones and offset
Date.prototype.getDaysDifferenceCorrected = function (other) {
 var millisecondsDifference = (this - other);
 // correct for offset difference. offsets are in minutes, the difference is in milliseconds
 millisecondsDifference += (other.getTimezoneOffset()- this.getTimezoneOffset()) * 60000;
 // return day total. 1 day is 86400000 milliseconds, floor the value to return only full days
 return Math.floor(millisecondsDifference / 86400000);
}
</code></pre>

for testing i used the following JavaScript tests in Qunit

<pre><code>var runweekcompare = function(result, expected) {
 equal(result, expected,'Week nr expected value: ' + expected + ' Actual value: ' + result);
}

test('first week number test', function () {
 expect(5);
 var temp = new Date(2016, 0, 4); // is the monday of the first week of the year
 runweekcompare(temp.getWeek(), 1);
 var temp = new Date(2016, 0, 4, 23, 50); // is the monday of the first week of the year
 runweekcompare(temp.getWeek(), 1);
 var temp = new Date(2016, 0, 10, 23, 50); // is the sunday of the first week of the year
 runweekcompare(temp.getWeek(), 1);
 var temp = new Date(2016, 0, 11, 23, 50); // is the second week of the year
 runweekcompare(temp.getWeek(), 2);
 var temp = new Date(2016, 1, 29, 23, 50); // is the 9th week of the year
 runweekcompare(temp.getWeek(), 9);
});

test('first day is part of last years last week', function () {
 expect(2);
 var temp = new Date(2016, 0, 1, 23, 50); // is the first last week of the previous year
 runweekcompare(temp.getWeek(), 53);
 var temp = new Date(2011, 0, 2, 23, 50); // is the first last week of the previous year
 runweekcompare(temp.getWeek(), 52);
});

test('last day is part of next years first week', function () {
 var temp = new Date(2013, 11, 30); // is part of the first week of 2014
 runweekcompare(temp.getWeek(), 1);
});

test('summer winter time change', function () {
 expect(2);
 var temp = new Date(2000, 2, 26); 
 runweekcompare(temp.getWeek(), 12);
 var temp = new Date(2000, 2, 27); 
 runweekcompare(temp.getWeek(), 13);
});

test('full 20 year test', function () {
 //expect(20 * 12 * 28 * 2);
 for (i = 2000; i &lt; 2020; i++) {
 for (month = 0; month &lt; 12; month++) {
 for (day = 1; day &lt; 29 ; day++) {
 var temp = new Date(i, month, day);
 var expectedweek = temp.getWeek();
 var temp2 = new Date(i, month, day, 23, 50);
 var resultweek = temp.getWeek();
 equal(expectedweek, Math.round(expectedweek), 'week number whole number expected ' + Math.round(expectedweek) + ' resulted week nr ' + expectedweek);
 equal(resultweek, expectedweek, 'Week nr expected value: ' + expectedweek + ' Actual value: ' + resultweek + ' for year ' + i + ' month ' + month + ' day ' + day);
 }
 }
 }
});
</code></pre>

blocks|key|267638|text|下面是Typescript的一个小调整，它还将返回周开始和周结束的日期。我认为必须在用户界面中显示这些数字是很常见的，因为人们通常不会记住星期数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|267639|​|267640|function+getWeekNumber(d:+Date)+{
++//+Copy+date+so+don't+modify+original
++d+=+new+Date(Date.UTC(d.getFullYear(),+d.getMonth(),+d.getDate()));
++//+Set+to+nearest+Thursday:+current+date+%2B+4+-+current+day+number+Make
++//+Sunday's+day+number+7
++d.setUTCDate(d.getUTCDate()+%2B+4+-+(d.getUTCDay()+%7C%7C+7));
++//+Get+first+day+of+year
++const+yearStart+=+new+Date(Date.UTC(d.getUTCFullYear(),+0,+1));
++//+Calculate+full+weeks+to+nearest+Thursday
++const+weekNo+=+Math.ceil(
++++((d.getTime()+-+yearStart.getTime())+/+86400000+%2B+1)+/+7
++);

++const+weekStartDate+=+new+Date(d.getTime());
++weekStartDate.setUTCDate(weekStartDate.getUTCDate()+-+3);

++const+weekEndDate+=+new+Date(d.getTime());
++weekEndDate.setUTCDate(weekEndDate.getUTCDate()+%2B+3);

++return+[d.getUTCFullYear(),+weekNo,+weekStartDate,+weekEndDate]+as+const;
}|code-block|syntax|javascript|267641|267642|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|N|8|@]|9|@]|A|$G|H]]|$1|I|3|C|5|6|7|O|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|P|8|@]|9|@]|A|$]]]|K|$]]

Here is a slight adaptation for Typescript that will also return the dates for the week start and week end. I think it's common to have to display those in a user interface, since people don't usually remember week numbers.
<div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>function getWeekNumber(d: Date) {
 // Copy date so don't modify original
 d = new Date(Date.UTC(d.getFullYear(), d.getMonth(), d.getDate()));
 // Set to nearest Thursday: current date + 4 - current day number Make
 // Sunday's day number 7
 d.setUTCDate(d.getUTCDate() + 4 - (d.getUTCDay() || 7));
 // Get first day of year
 const yearStart = new Date(Date.UTC(d.getUTCFullYear(), 0, 1));
 // Calculate full weeks to nearest Thursday
 const weekNo = Math.ceil(
 ((d.getTime() - yearStart.getTime()) / 86400000 + 1) / 7
 );

 const weekStartDate = new Date(d.getTime());
 weekStartDate.setUTCDate(weekStartDate.getUTCDate() - 3);

 const weekEndDate = new Date(d.getTime());
 weekEndDate.setUTCDate(weekEndDate.getUTCDate() + 3);

 return [d.getUTCFullYear(), weekNo, weekStartDate, weekEndDate] as const;
}</code></pre>
</div>
</div>

blocks|key|267585|text|我尝试了很多，以获得最短的代码，以获得周数ISO-conform。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|267586|Date.prototype.getWeek=function(){
++++var+date=new+Date(this);
++++date.setHours(0,0,0,0);
++++return+Math.round(((date.setDate(this.getDate()%2B2-(this.getDay()%7C%7C7))-date.setMonth(0,4))/8.64e7%2B3%2B(date.getDay()%7C%7C7))/7)%2B"/"%2Bdate.getFullYear();}|code-block|syntax|javascript|267587|为了避免更改原始this，必须使用变量date。我使用setDate()和setMonth()的返回值省去了getTime()以节省代码长度，并且我使用了一天中毫秒的指数，而不是单个元素的乘法或带有五个零的数字。this为日期或毫秒数，返回值为String，如"49/2017“。|offset|length|style|CODE|267588|entityMap^0|0|0|8|4|J|4|R|9|11|A|1I|9|2Y|4|3E|6|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]|$I|V|J|W|K|L]|$I|X|J|Y|K|L]|$I|Z|J|10|K|L]|$I|11|J|12|K|L]|$I|13|J|14|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|N|$]]

I tried a lot to get the shortest code to get the weeknumber ISO-conform.

<pre><code>Date.prototype.getWeek=function(){
 var date=new Date(this);
 date.setHours(0,0,0,0);
 return Math.round(((date.setDate(this.getDate()+2-(this.getDay()||7))-date.setMonth(0,4))/8.64e7+3+(date.getDay()||7))/7)+"/"+date.getFullYear();}
</code></pre>

The variable <code>date</code> is necessary to avoid to alter the original <code>this</code>. I used the return values of <code>setDate()</code> and <code>setMonth()</code> to dispense with <code>getTime()</code> to save code length and I used an expontial number for milliseconds of a day instead of a multiplication of single elements or a number with five zeros. <code>this</code> is Date or Number of milliseconds, return value is <code>String</code> e.g. "49/2017".

blocks|key|270957|text|另一个基于库的选项:使用d3-time-format|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|270958|const+formatter+=+d3.timeFormat('%25U');
const+weekNum+=+formatter(new+Date());|code-block|syntax|javascript|270959|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/d3/d3-time-format#timeFormat^0|C|E|C|E|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

Another library-based option: use <a href="https://github.com/d3/d3-time-format#timeFormat" rel="nofollow noreferrer"><code>d3-time-format</code></a>:
<pre><code>const formatter = d3.timeFormat('%U');
const weekNum = formatter(new Date());
</code></pre>

blocks|key|265444|text|针对ISO-8601调整的Angular2%2B+DatePipe的最短解决方法：|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|265445|import+{DatePipe}+from+"@angular/common";

public+rightWeekNum:+number+=+0;
++
constructor(private+datePipe:+DatePipe)+{+}
++++
calcWeekOfTheYear(dateInput:+Date)+{
++let+falseWeekNum+=+parseInt(this.datePipe.transform(dateInput,+'ww'));
++this.rightWeekNum+=+(dateInput.getDay()+==+0)+?+falseWeekNumber-1+:+falseWeekNumber;
}|code-block|syntax|javascript|265446|entityMap^0|D|9|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

Shortest workaround for Angular2+ DatePipe, adjusted for ISO-8601:
<pre><code>import {DatePipe} from &quot;@angular/common&quot;;

public rightWeekNum: number = 0;
 
constructor(private datePipe: DatePipe) { }
 
calcWeekOfTheYear(dateInput: Date) {
 let falseWeekNum = parseInt(this.datePipe.transform(dateInput, 'ww'));
 this.rightWeekNum = (dateInput.getDay() == 0) ? falseWeekNumber-1 : falseWeekNumber;
}
</code></pre>

blocks|key|267644|text|灵感来自RobG's+answer。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|267645|我想要的是给定日期的星期几。因此，我的答案只是基于一周中的哪一天星期日。但你可以选择另一天(即星期一、星期二……)；|267646|首先，我找到给定日期中的星期天，然后计算星期。|267647|​|267648|function+getStartWeekDate(d+=+null)+{
++const+now+=+d+%7C%7C+new+Date();
++now.setHours(0,+0,+0,+0);
++const+sunday+=+new+Date(now);
++sunday.setDate(sunday.getDate()+-+sunday.getDay());
++return+sunday;
}

function+getWeek(date)+{
++const+sunday+=+getStartWeekDate(date);
++const+yearStart+=+new+Date(Date.UTC(2021,+0,+1));
++const+weekNo+=+Math.ceil((((sunday+-+yearStart)+/+86400000)+%2B+1)+/+7);
++return+weekNo;
}
//+tests
for+(let+i+=+0;+i+<+7;+i%2B%2B)++{
++let+m+=+14+%2B+i;
++let+x+=+getWeek(new+Date(2021,+2,+m));
++console.log('week+num:+'+%2B+x,+x+%2B+'+==+'+%2B+11,+x+==+11,+m);
}

for+(let+i+=+0;+i+<+7;+i%2B%2B)++{
++let+m+=+21+%2B+i;
++let+x+=+getWeek(new+Date(2021,+2,+m));
++console.log('week+num:+'+%2B+x,+x+%2B+'+==+'+%2B+12,+x+==+12,+'date+day:+'+%2B++m);
}
for+(let+i+=+0;+i+<+4;+i%2B%2B)++{
++let+m+=+28+%2B+i;
++let+x+=+getWeek(new+Date(2021,+2,+m));
++console.log('week+num:+'+%2B+x,+x+%2B+'+==+'+%2B+13,+x+==+13,+'date+day:+'+%2B+m);
}
for+(let+i+=+0;+i+<+3;+i%2B%2B)++{
++let+m+=+1+%2B+i;
++let+x+=+getWeek(new+Date(2021,+3,+m));
++console.log('week+num:+'+%2B+x,+x+%2B+'+==+'+%2B+13,+x+==+13,+'date+day:+'+%2B++m);
}

for+(let+i+=+0;+i+<+7;+i%2B%2B)++{
++let+m+=+4+%2B+i;
++let+x+=+getWeek(new+Date(2021,+3,+m));
++console.log('week+num:+'+%2B+x,+x+%2B+'+==+'+%2B+14,+x+==+14,+'date+day:+'+%2B++m);
}|code-block|syntax|javascript|267649|267650|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/6117814/get-week-of-year-in-javascript-like-in-php#6117889^0|4|D|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@]|9|@$A|Y|B|Z|1|10]]|C|$]]|$1|D|3|E|5|6|7|11|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|12|8|@]|9|@]|C|$]]|$1|H|3|I|5|6|7|13|8|@]|9|@]|C|$]]|$1|J|3|K|5|L|7|14|8|@]|9|@]|C|$M|N]]|$1|O|3|I|5|6|7|15|8|@]|9|@]|C|$]]|$1|P|3|-4|5|6|7|16|8|@]|9|@]|C|$]]]|Q|$R|$5|S|T|U|C|$V|W]]]]

Inspired from <a href="https://stackoverflow.com/questions/6117814/get-week-of-year-in-javascript-like-in-php#6117889">RobG's answer</a>.
What I wanted is the day of the week of a given date. So my answer is simply based on the day of the week Sunday. But you can choose the other day (i.e. Monday, Tuesday...);
First I find the Sunday in a given date and then calculate the week.
<div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>function getStartWeekDate(d = null) {
 const now = d || new Date();
 now.setHours(0, 0, 0, 0);
 const sunday = new Date(now);
 sunday.setDate(sunday.getDate() - sunday.getDay());
 return sunday;
}

function getWeek(date) {
 const sunday = getStartWeekDate(date);
 const yearStart = new Date(Date.UTC(2021, 0, 1));
 const weekNo = Math.ceil((((sunday - yearStart) / 86400000) + 1) / 7);
 return weekNo;
}
// tests
for (let i = 0; i &lt; 7; i++) {
 let m = 14 + i;
 let x = getWeek(new Date(2021, 2, m));
 console.log('week num: ' + x, x + ' == ' + 11, x == 11, m);
}

for (let i = 0; i &lt; 7; i++) {
 let m = 21 + i;
 let x = getWeek(new Date(2021, 2, m));
 console.log('week num: ' + x, x + ' == ' + 12, x == 12, 'date day: ' + m);
}
for (let i = 0; i &lt; 4; i++) {
 let m = 28 + i;
 let x = getWeek(new Date(2021, 2, m));
 console.log('week num: ' + x, x + ' == ' + 13, x == 13, 'date day: ' + m);
}
for (let i = 0; i &lt; 3; i++) {
 let m = 1 + i;
 let x = getWeek(new Date(2021, 3, m));
 console.log('week num: ' + x, x + ' == ' + 13, x == 13, 'date day: ' + m);
}

for (let i = 0; i &lt; 7; i++) {
 let m = 4 + i;
 let x = getWeek(new Date(2021, 3, m));
 console.log('week num: ' + x, x + ' == ' + 14, x == 14, 'date day: ' + m);
}</code></pre>
</div>
</div>

blocks|key|270878|text|now+=+new+Date();
today+=+new+Date(now.getFullYear(),+now.getMonth(),+now.getDate());
firstOfYear+=+new+Date(now.getFullYear(),+0,+1);
numOfWeek+=+Math.ceil((((today+-+firstOfYear)+/+86400000)-1)/7);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|270879|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>now = new Date();
today = new Date(now.getFullYear(), now.getMonth(), now.getDate());
firstOfYear = new Date(now.getFullYear(), 0, 1);
numOfWeek = Math.ceil((((today - firstOfYear) / 86400000)-1)/7);
</code></pre>

How do I get the current weeknumber of the year, like PHP's <code>date('W')</code>?

It should be the <a href="http://en.wikipedia.org/wiki/ISO_8601" rel="noreferrer">ISO-8601</a> week number of year, weeks starting on Monday.

Get week of year in JavaScript like in PHP

如何获得一年中的当前周数，如PHP的date('W')它应该是一年的 week数，从星期一开始。

问在JavaScript中获取一年中的星期
EN

回答 20

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