JavaScript Date.getWeek()? [duplicate]

问题:

This question already has an answer here:

• Get week of year in JavaScript like in PHP 15 answers

I'm looking for a tested solid solution for getting current week of the year for specified date. All I can find are the ones that doesn't take in account leap years or just plain wrong. Does anyone have this type of stuff?

Or even better a function that says how many weeks does month occupy. It is usually 5, but can be 4 (feb) or 6 (1st is sunday and month has 30-31 days in it)

================= UPDATE:

Still not sure about getting week #, but since I figured out it won't solve my problem with calculating how many weeks month occupy, I abandoned it.

Here's a function to find out how many weeks exactly month occupy on the calendar:

getWeeksNum: function(year, month) {     var daysNum = 32 - new Date(year, month, 32).getDate(),         fDayO = new Date(year, month, 1).getDay(),         fDay = fDayO ? (fDayO - 1) : 6,         weeksNum = Math.ceil((daysNum + fDay) / 7);     return weeksNum; } 

回答1:

/**  * Returns the week number for this date.  dowOffset is the day of week the week  * "starts" on for your locale - it can be from 0 to 6. If dowOffset is 1 (Monday),  * the week returned is the ISO 8601 week number.  * @param int dowOffset  * @return int  */ Date.prototype.getWeek = function (dowOffset) { /*getWeek() was developed by Nick Baicoianu at MeanFreePath: http://www.meanfreepath.com */      dowOffset = typeof(dowOffset) == 'int' ? dowOffset : 0; //default dowOffset to zero     var newYear = new Date(this.getFullYear(),0,1);     var day = newYear.getDay() - dowOffset; //the day of week the year begins on     day = (day >= 0 ? day : day + 7);     var daynum = Math.floor((this.getTime() - newYear.getTime() -      (this.getTimezoneOffset()-newYear.getTimezoneOffset())*60000)/86400000) + 1;     var weeknum;     //if the year starts before the middle of a week     if(day  52) {             nYear = new Date(this.getFullYear() + 1,0,1);             nday = nYear.getDay() - dowOffset;             nday = nday >= 0 ? nday : nday + 7;             /*if the next year starts before the middle of               the week, it is week #1 of that year*/             weeknum = nday 

Usage:

var mydate = new Date(2011,2,3); // month number starts from 0 // or like this var mydate = new Date('March 3, 2011'); alert(mydate.getWeek()); 

Source

回答2:

Consider using my implementation of "Date.prototype.getWeek", think is more accurate than the others i have seen here :)

Date.prototype.getWeek = function(){     // We have to compare against the first monday of the year not the 01/01     // 60*60*24*1000 = 86400000     // 'onejan_next_monday_time' reffers to the miliseconds of the next monday after 01/01      var day_miliseconds = 86400000,         onejan = new Date(this.getFullYear(),0,1,0,0,0),         onejan_day = (onejan.getDay()==0) ? 7 : onejan.getDay(),         days_for_next_monday = (8-onejan_day),         onejan_next_monday_time = onejan.getTime() + (days_for_next_monday * day_miliseconds),         // If one jan is not a monday, get the first monday of the year         first_monday_year_time = (onejan_day>1) ? onejan_next_monday_time : onejan.getTime(),         this_date = new Date(this.getFullYear(), this.getMonth(),this.getDate(),0,0,0),// This at 00:00:00         this_time = this_date.getTime(),         days_from_first_monday = Math.round(((this_time - first_monday_year_time) / day_miliseconds));      var first_monday_year = new Date(first_monday_year_time);      // We add 1 to "days_from_first_monday" because if "days_from_first_monday" is *7,     // then 7/7 = 1, and as we are 7 days from first monday,     // we should be in week number 2 instead of week number 1 (7/7=1)     // We consider week number as 52 when "days_from_first_monday" is lower than 0,     // that means the actual week started before the first monday so that means we are on the firsts     // days of the year (ex: we are on Friday 01/01, then "days_from_first_monday"=-3,     // so friday 01/01 is part of week number 52 from past year)     // "days_from_first_monday= 52 (Math.ceil(366/7)=53) and thats wrong      return (days_from_first_monday>=0 && days_from_first_monday

You can check my public repo here https://bitbucket.org/agustinhaller/date.getweek (Tests included)

回答3:

Get week number

Date.prototype.getWeek = function() {     var dt = new Date(this.getFullYear(),0,1);     return Math.ceil((((this - dt) / 86400000) + dt.getDay()+1)/7); };  var myDate = new Date(2013, 3, 25); // 2013, 25 April  console.log(myDate.getWeek()); 

回答4:

I know this is an old question, but maybe it helps:

http://weeknumber.net/how-to/javascript

回答5:

/*get the week number by following the norms of ISO 8601*/ function getWeek(dt){ 	var calc=function(o){ 		if(o.dtmin.getDay()!=1){ 			if(o.dtmin.getDay()=1 && dt.getDate()=5 || dt.getDay()==0)){ 		var pyData={"dtmin":new Date(dt.getFullYear()-1,0,1,0,0,0,0),"dtmax":new Date(dt.getFullYear()-1,11,getNbDaysInAMonth(dt.getFullYear()-1,12),0,0,0,0),"w":0}; 		calc(pyData); 		return pyData.w; 	}else{ 		var ayData={"dtmin":new Date(dt.getFullYear(),0,1,0,0,0,0),"dtmax":new Date(dt.getFullYear(),dt.getMonth(),dt.getDate(),0,0,0,0),"w":0}, 			nd12m=getNbDaysInAMonth(dt.getFullYear(),12); 		if(dt.getMonth()==12 && dt.getDay()!=0 && dt.getDay()

回答6:

For those looking for a more simple approach;

Date.prototype.getWeek = function() {   var onejan = new Date(this.getFullYear(),0,1);   var today = new Date(this.getFullYear(),this.getMonth(),this.getDate());   var dayOfYear = ((today - onejan + 86400000)/86400000);   return Math.ceil(dayOfYear/7) }; 

Use with:

var today = new Date(); var currentWeekNumber = today.getWeek(); console.log(currentWeekNumber); 

文章来源: JavaScript Date.getWeek()? [duplicate]