Get Weeks In Month Through Javascript

None of the solutions proposed here don't works correctly, so I wrote my own variant and it works for any cases.

Simple and working solution:

 
/** * Returns count of weeks for year and month * * @param {Number} year - full year (2016) * @param {Number} month_number - month_number is in the range 1..12 * @returns {number} */ var weeksCount = function(year, month_number) { var firstOfMonth = new Date(year, month_number - 1, 1); var day = firstOfMonth.getDay() || 6; day = day === 1 ? 0 : day; if (day) { day-- } var diff = 7 - day; var lastOfMonth = new Date(year, month_number, 0); var lastDate = lastOfMonth.getDate(); if (lastOfMonth.getDay() === 1) { diff--; } var result = Math.ceil((lastDate - diff) / 7); return result + 1; }; 
 

This is very simple two line code. and i have tested 100%.

Date.prototype.getWeekOfMonth = function () { var firstDay = new Date(this.setDate(1)).getDay(); var totalDays = new Date(this.getFullYear(), this.getMonth() + 1, 0).getDate(); return Math.ceil((firstDay + totalDays) / 7); } 

How to use

var totalWeeks = new Date().getWeekOfMonth(); console.log('Total Weeks in the Month are : + totalWeeks ); 

You'll have to calculate it.

You can do something like

var firstDay = new Date(2010, 0, 1).getDay(); // get the weekday january starts on var numWeeks = 5 + (firstDay >= 5 ? 1 : 0); // if the months starts on friday, then it will end on sunday 

Now we just need to genericize it.

var dayThreshold = [ 5, 1, 5, 6, 5, 6, 5, 5, 6, 5, 6, 5 ]; function GetNumWeeks(month, year) { var firstDay = new Date(year, month, 1).getDay(); var baseWeeks = (month == 1 ? 4 : 5); // only February can fit in 4 weeks // TODO: account for leap years return baseWeeks + (firstDay >= dayThreshold[month] ? 1 : 0); // add an extra week if the month starts beyond the threshold day. } 

Note: When calling, remember that months are zero indexed in javascript (i.e. January == 0).

function weeksinMonth(m, y){ y= y || new Date().getFullYear(); var d= new Date(y, m, 0); return Math.floor((d.getDate()- 1)/7)+ 1; } alert(weeksinMonth(3)) 

// the month range for this method is 1 (january)-12(december)

The most easy to understand way is

<div id="demo"></div> <script type="text/javascript"> function numberOfDays(year, month) { var d = new Date(year, month, 0); return d.getDate(); } function getMonthWeeks(year, month_number) { var $num_of_days = numberOfDays(year, month_number) , $num_of_weeks = 0 , $start_day_of_week = 0; for(i=1; i<=$num_of_days; i++) { var $day_of_week = new Date(year, month_number, i).getDay(); if($day_of_week==$start_day_of_week) { $num_of_weeks++; } } return $num_of_weeks; } var d = new Date() , m = d.getMonth() , y = d.getFullYear(); document.getElementById('demo').innerHTML = getMonthWeeks(y, m); </script> 

using moment js

function getWeeksInMonth(year, month){ var monthStart = moment().year(year).month(month).date(1); var monthEnd = moment().year(year).month(month).endOf('month'); var numDaysInMonth = moment().year(year).month(month).endOf('month').date(); //calculate weeks in given month var weeks = Math.ceil((numDaysInMonth + monthStart.day()) / 7); var weekRange = []; var weekStart = moment().year(year).month(month).date(1); var i=0; while(i<weeks){ var weekEnd = moment(weekStart); if(weekEnd.endOf('week').date() <= numDaysInMonth && weekEnd.month() == month) { weekEnd = weekEnd.endOf('week').format('LL'); }else{ weekEnd = moment(monthEnd); weekEnd = weekEnd.format('LL') } weekRange.push({ 'weekStart': weekStart.format('LL'), 'weekEnd': weekEnd }); weekStart = weekStart.weekday(7); i++; } return weekRange; } console.log(getWeeksInMonth(2016, 7)) 

ES6 variant, using consistent zero-based months index. Tested for years from 2015 to 2025.

/** * Returns number of weeks * * @param {Number} year - full year (2018) * @param {Number} month - zero-based month index (0-11) * @param {Boolean} fromMonday - false if weeks start from Sunday, true - from Monday. * @returns {number} */ const weeksInMonth = (year, month, fromMonday = false) => { const first = new Date(year, month, 1); const last = new Date(year, month + 1, 0); let dayOfWeek = first.getDay(); if (fromMonday && dayOfWeek === 0) dayOfWeek = 7; let days = dayOfWeek + last.getDate(); if (fromMonday) days -= 1; return Math.ceil(days / 7); }

You could use my time.js library. Here's the weeksInMonth function:

// http://github.com/augustl/time.js/blob/623e44e7a64fdaa3c908debdefaac1618a1ccde4/time.js#L67 weeksInMonth: function(){ var millisecondsInThisMonth = this.clone().endOfMonth().epoch() - this.clone().firstDayInCalendarMonth().epoch(); return Math.ceil(millisecondsInThisMonth / MILLISECONDS_IN_WEEK); }, 

It might be a bit obscure since the meat of the functionality is in endOfMonth and firstDayInCalendarMonth, but you should at least be able to get some idea of how it works.

This works for me,

function(d){ var firstDay = new Date(this.getFullYear(), this.getMonth(), 1).getDay(); return Math.ceil((d.getDate() + (firstDay - 1))/7); } 

"d" should be the date.

A little rudimentary, yet should cater for original post :

/** * @param {date} 2020-01-30 * @return {int} count */ this.numberOfCalendarWeekLines = date => { // get total let lastDayOfMonth = new Date( new Date( date ).getFullYear(), new Date( date ).getMonth() + 1, 0 ); let manyDaysInMonth = lastDayOfMonth.getDate(); // iterate over month - from 1st // count calendar week lines by occurrence // of a Saturday ( s m t w t f s ) let countCalendarWeekLines = 0; for ( let i = 1; i <= manyDaysInMonth; i++ ) { if ( new Date( new Date( date ).setDate( i ) ).getDay() === 6 ) countCalendarWeekLines++; } // days after last occurrence of Saturday // leaked onto new line? if ( lastDayOfMonth.getDay() < 6 ) countCalendarWeekLines++; return countCalendarWeekLines; }; 

Thanks to Ed Poor for his solution, this is the same as Date prototype.

Date.prototype.countWeeksOfMonth = function() { var year = this.getFullYear(); var month_number = this.getMonth(); var firstOfMonth = new Date(year, month_number-1, 1); var lastOfMonth = new Date(year, month_number, 0); var used = firstOfMonth.getDay() + lastOfMonth.getDate(); return Math.ceil( used / 7); } 

So you can use it like

var weeksInCurrentMonth = new Date().countWeeksOfMonth(); var weeksInDecember2012 = new Date(2012,12,1).countWeeksOfMonth(); // 6 

function getWeeksInMonth(month_number, year) { console.log("year - "+year+" month - "+month_number+1); var day = 0; var firstOfMonth = new Date(year, month_number, 1); var lastOfMonth = new Date(year, parseInt(month_number)+1, 0); if (firstOfMonth.getDay() == 0) { day = 2; firstOfMonth = firstOfMonth.setDate(day); firstOfMonth = new Date(firstOfMonth); } else if (firstOfMonth.getDay() != 1) { day = 9-(firstOfMonth.getDay()); firstOfMonth = firstOfMonth.setDate(day); firstOfMonth = new Date(firstOfMonth); } var days = (lastOfMonth.getDate() - firstOfMonth.getDate())+1 return Math.ceil( days / 7); } 

It worked for me. Please try

Thanks all

This piece of code give you the exact number of weeks in a given month:

Date.prototype.getMonthWeek = function(monthAdjustement) { var firstDay = new Date(this.getFullYear(), this.getMonth(), 1).getDay(); var returnMessage = (Math.ceil(this.getDate()/7) + Math.floor(((7-firstDay)/7))); return returnMessage; } 

The monthAdjustement variable adds or substract the month that you are currently in

I use it in a calendar project in JS and the equivalent in Objective-C and it works well

 function weekCount(year, month_number, day_start) { // month_number is in the range 1..12 // day_start is in the range 0..6 (where Sun=0, Mon=1, ... Sat=6) var firstOfMonth = new Date(year, month_number-1, 1); var lastOfMonth = new Date(year, month_number, 0); var dayOffset = (firstOfMonth.getDay() - day_start + 7) % 7; var used = dayOffset + lastOfMonth.getDate(); return Math.ceil( used / 7); } 

I know this is coming late, I have seen codes upon codes trying to get the number of weeks a particular month falls on, but many have not been really precise but most have been really informative and reusable, I'm not an expert programmer but I can really think and thanks to some codes by some people I was able to arrive at a conclusion.

function convertDate(date) {//i lost the guy who owns this code lol var yyyy = date.getFullYear().toString(); var mm = (date.getMonth()+1).toString(); var dd = date.getDate().toString(); var mmChars = mm.split(''); var ddChars = dd.split(''); return yyyy + '-' + (mmChars[1]?mm:"0"+mmChars[0]) + '-' + (ddChars[1]?dd:"0"+ddChars[0]); } //this line of code from https://stackoverflow.com/a/4028614/2540911 var days = ['Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday']; var myDate = new Date('2019-03-2'); //var myDate = new Date(); //or todays date var c = convertDate(myDate).split("-"); let yr = c[0], mth = c[1], dy = c[2]; weekCount(yr, mth, dy) //Ahh yes, this line of code is from Natim Up there, incredible work, https://stackoverflow.com/a/2485172/2540911 function weekCount(year, month_number, startDayOfWeek) { // month_number is in the range 1..12 console.log(weekNumber); // Get the first day of week week day (0: Sunday, 1: Monday, ...) var firstDayOfWeek = startDayOfWeek || 0; var firstOfMonth = new Date(year, month_number-1, 1); var lastOfMonth = new Date(year, month_number, 0); var numberOfDaysInMonth = lastOfMonth.getDate(); var first = firstOfMonth.getDate(); //initialize first week let weekNumber = 1; while(first-1 < numberOfDaysInMonth){ // add a day firstOfMonth = firstOfMonth.setDate(firstOfMonth.getDate() + 1);//this line of code from https://stackoverflow.com/a/9989458/2540911 if(days[firstOfMonth.getDay()] === "Sunday"){//get new week every new sunday according the local date format //get newWeek weekNumber++; } if(weekNumber === 3 && days[firstOfMonth.getDay()] === "Friday") alert(firstOfMonth); first++ } } 

I needed this code to generate a schedule or event scheduler for a church on every 3rd friday of a new month, so you can modify this to suit your or just pick your specific date, not "friday and specify the week of the month and Voila!! here you go

None of the solutions here really worked for me. Here is my crack at it.

// Example // weeksOfMonth(2019, 9) // October // Result: 5 weeksOfMonth (year, monthIndex) { const d = new Date(year, monthIndex+ 1, 0) const adjustedDate = d.getDate() + d.getDay() return Math.ceil(adjustedDate / 7) } 

Every solutions helped but nothing was working for me so I did my own with moment library :

const getWeeksInAMonth = (currentDate: string) => { const startOfMonth = moment(currentDate).startOf("month") const endOfMonth = moment(currentDate).endOf("month") return moment(endOfMonth).week() - moment(startOfMonth).week() + 1 } 

Wrote something extremely simple and direct and works for his usecase which was also my usecase

function countWeeksInMonth(year, month_number) { // month_number is in the range 1..12 const date = new Date(year, month_number); const startDay = new Date(year, month_number, 1).getDay(); let totalDays = new Date(year, month_number + 1, 0).getDate(); let weeks = 0; console.log("total-days initial", { totalDays }); // Step 1: Remove first week totalDays -= 7 - startDay; weeks += 1; console.log("Step 1:", { totalDays, weeks }); // Step 2: Count the full weeks weeks += Math.floor(totalDays / 7); console.log("Step 2:", { weeks }); // Step 3: Check for overflowing weeks if (totalDays % 7 > 0) weeks += 1; console.log("Step 3:", { weeks }); return weeks; } 

Why not just count them? Might take up one or two more CPU cycles, but I doubt it would matter - and the accuracy is very high. This procedure also allows you to select which day your week starts on.

weeksInMonth(year, month, weekStartDay = 0){ // Iterate over all the days in the month, each time // a certain day (weekStartDay - default sunday) is passed, // add one to the count - unless the first day happens to be // weekStartDay let count = 1; let currentDate = new Date(year, month, 1); let endDate = new Date(year, month + 1, 0); let isFirst = true; while(currentDate.getTime() <= endDate.getTime()){ if(currentDate.getDay() === weekStartDay && !isFirst){ count++; } isFirst = false; // Increment the current date currentDate.setDate(currentDate.getDate() + 1); } return count; } 

weeksInMonth(2024, 7); >>> 6