How to determine number Saturdays and Sundays comes between two dates in java script

Question

I have requirement as follows I have two dates i need to find how may saturdays and sundays will come in between
Date1: 02/06/2011
Date2: 02/07/2011
10 days are weekends
Thanks Srini

Answer 1

O(1) solution with no loops:

function countWeekendDays( d0, d1 )
{
  var ndays = 1 + Math.round((d1.getTime()-d0.getTime())/(24*3600*1000));
  var nsaturdays = Math.floor( (d0.getDay()+ndays) / 7 );
  return 2*nsaturdays + (d0.getDay()==0) - (d1.getDay()==6);
}

jsFiddle

Answer 2

Edited to count number of weekend days instead of number of weekends. http://jsfiddle.net/bRgUq/3/

function CalculateWeekendDays(fromDate, toDate){
    var weekendDayCount = 0;

    while(fromDate < toDate){
        fromDate.setDate(fromDate.getDate() + 1);
        if(fromDate.getDay() === 0 || fromDate.getDay() == 6){
            ++weekendDayCount ;
        }
    }

    return weekendDayCount ;
}

console.log(CalculateWeekendDays(new Date(2011, 6, 2), new Date(2011, 7, 2)));

Answer 3

According to your dates, they are not in US format (at least not if there are 10 weekend days between them). You can get them in US format with something such as...

var chunks = str.split('/');
str = [chunks[1], chunks[0], chunks[2]].join('/');

This code loops through each day between the dates and increments a counter if the day is a Saturday or Sunday.

var start = new Date('06/02/2011'),
    finish = new Date('07/02/2011'),
    dayMilliseconds = 1000 * 60 * 60 * 24;

var weekendDays = 0;

while (start <= finish) {
    var day = start.getDay()
    if (day == 0 || day == 6) {
        weekendDays++;
    }
    start = new Date(+start + dayMilliseconds);
}

jsFiddle.