Get Weeks In Month Through Javascript

Question

In Javascript, how do I get the number of weeks in a month? I can\'t seem to find code for this anywhere.

I need this to be able to know how many rows I need for a g

Answer 1

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.

Answer 2

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)
}

Answer 3

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();

    // itterate through month - from 1st
    // count calender week lines by occurance
    // 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 occurance of Saturday 
    // leaked onto new line?
    if ( lastDayOfMonth.getDay() < 6 ) countCalendarWeekLines++;

    return countCalendarWeekLines;

};

Answer 4

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 ); 

Answer 5

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

Answer 6

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