How many specific days within a date range in Javascript

问题

I have two dates. One is starting date and another is ending date. I want to calculate how many Saturdays, Mondays and Wednesdays falls within the date range? How can I solve it? I saw several tutorial but they are only counting the dates within date range. Thanks in advance. I am using the following code to calculate only business days but I need only how many saturdays, mondays and wednesdays falls within the date range.

<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>JS Bin</title>
<!--[if IE]>
  <script src="http://html5shiv.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->
  <script>
        function calcBusinessDays(dDate1, dDate2) { // input given as Date objects
        var iWeeks, iDateDiff, iAdjust = 0;
        if (dDate2 < dDate1) return -1; // error code if dates transposed
        var iWeekday1 = dDate1.getDay(); // day of week
        var iWeekday2 = dDate2.getDay();
        iWeekday1 = (iWeekday1 == 0) ? 7 : iWeekday1; // change Sunday from 0 to 7
        iWeekday2 = (iWeekday2 == 0) ? 7 : iWeekday2;
        if ((iWeekday1 > 5) && (iWeekday2 > 5)) iAdjust = 1; // adjustment if both days on weekend
        iWeekday1 = (iWeekday1 > 5) ? 5 : iWeekday1; // only count weekdays
        iWeekday2 = (iWeekday2 > 5) ? 5 : iWeekday2;

        // calculate differnece in weeks (1000mS * 60sec * 60min * 24hrs * 7 days = 604800000)
        iWeeks = Math.floor((dDate2.getTime() - dDate1.getTime()) / 604800000)

        if (iWeekday1 <= iWeekday2) {
          iDateDiff = (iWeeks * 5) + (iWeekday2 - iWeekday1)
        } else {
          iDateDiff = ((iWeeks + 1) * 5) - (iWeekday1 - iWeekday2)
        }

        iDateDiff -= iAdjust // take into account both days on weekend

        return (iDateDiff + 1); // add 1 because dates are inclusive
    }
    </script>
<style>
  article, aside, figure, footer, header, hgroup, 
  menu, nav, section { display: block; }
</style>
</head>
<body>
  <script>
    alert(calcBusinessDays(new Date("August 01, 2010 11:13:00"),new Date("August 31, 2010 11:13:00")));
  </script>
</body>
</html>

回答1:

My approach:

First, acquire a list of dates from a range between two dates:

function getDates(dateStart, dateEnd) {
  var currentDate = dateStart,
      dates = [];
  while(currentDate <= dateEnd) {

    // append date to array
    dates.push(currentDate);

    // add one day
    // automatically rolling over to next month
    var d = new Date(currentDate.valueOf());
    d.setDate(d.getDate() + 1);
    currentDate = d;

  }
  return dates;
}

Then cycle through those dates, filtering for a relevant work day index:

function filterWeekDays(dates, includeDays) {
  var weekdays = [];

  // cycle dates
  dates.forEach(function(day){

    // cycle days to be included (so==0, mo==1, etc.)
    includeDays.forEach(function(include) {
      if(day.getDay() == include) {
        weekdays.push(day);
      }
    });
  });
  return weekdays;
}

Filtering options:

With Sunday beeing 0 and Monday being 1, a list of Sun, Mon, Wed would be: [0, 1, 3]

JS Bin: http://jsbin.com/furupoqu/5/edit

回答2:

O(1) solution. Loops over days of the week (no more than 7), not the date range.

// days is an array of weekdays: 0 is Sunday, ..., 6 is Saturday
function countCertainDays( days, d0, d1 ) {
  var ndays = 1 + Math.round((d1-d0)/(24*3600*1000));
  var sum = function(a,b) {
    return a + Math.floor( (ndays+(d0.getDay()+6-b) % 7 ) / 7 ); };
  return days.reduce(sum,0);
}

For example, to count Mondays (1), Wednesdays (3) and Saturdays (6) in January of 2014:

countCertainDays([1,3,6],new Date(2014,0,1),new Date(2014,0,1)) // 1
countCertainDays([1,3,6],new Date(2014,0,1),new Date(2014,0,2)) // 1
countCertainDays([1,3,6],new Date(2014,0,1),new Date(2014,0,3)) // 1
countCertainDays([1,3,6],new Date(2014,0,1),new Date(2014,0,4)) // 2
countCertainDays([1,3,6],new Date(2014,0,1),new Date(2014,0,5)) // 2
countCertainDays([1,3,6],new Date(2014,0,1),new Date(2014,0,6)) // 3
countCertainDays([1,3,6],new Date(2014,0,1),new Date(2014,0,7)) // 3
countCertainDays([1,3,6],new Date(2014,0,1),new Date(2014,0,8)) // 4
countCertainDays([1,3,6],new Date(2014,0,1),new Date(2014,0,9)) // 4
countCertainDays([1,3,6],new Date(2014,0,1),new Date(2014,0,10)) // 4
countCertainDays([1,3,6],new Date(2014,0,1),new Date(2014,0,11)) // 5

Note: This assumes d0 and d1 are Date objects whose time of day are about the same. If you create Date objects only specifying year, month, and day, then there is no problem.

来源：https://stackoverflow.com/questions/21985259/how-many-specific-days-within-a-date-range-in-javascript

标签

javascript

timespan

dayofweek