How to calculate days between two date excluding weekends in angularjs?

Question

In my application i have two date picker as start date and end date. when user choose start and end date the system will show the days between two dates but excluding the saturday and sunday. How to calculate it by using angularjs?

Answer 1

Does something like this work:

var startDate = new Date("01-10-2020");
var endDate = new Date("01-20-2020");
var nextDay = new Date(startDate);
var cnt = 0;
do {
    /*if (nextDay.getDay() >= 1 && nextDay.getDay() <= 5) {
        cnt = cnt + 1;
    }*/
    cnt += (nextDay.getDay() >= 1 && nextDay.getDay() <= 5) ? 1 : 0;
    nextDay.setDate(nextDay.getDate() + 1);
} while (nextDay <= endDate);
console.log("Number of week days between " + startDate + " and " + endDate + " = " + cnt);

Here is the fiddler.

Answer 2

You don't want to do an expensive loop over every day to see whether it is Saturday or Sunday. The logic should be as follows:

• Work in UTC so we don't need to worry about time zone
• Calculate total number of calendar weeks. In a single calendar week, there are guaranteed to be 5 weekdays (not weekends == SAT || SUN)
• Calculate the remainder of days. This will be added to the calculation later.
• Determine the "finalAdjustment" by seeing if the remainder falls on weekend days.
• The number of weekdays is (5 * numWeeks) + remainderDays + finalAdjust

(function() {
  "use strict";

  var SUN = 0;
  var MON = 1;
  var TUE = 2;
  var WED = 3;
  var THU = 4;
  var FRI = 5;
  var SAT = 6;

  function isWeekendDay(day) {
    return day === SAT || day === SUN;
  }

  function numberWeekDays(start, end) {
    var numCalendarDays = (end - start) / 1000 / 60 / 60 / 24;
    var numWeeks = Math.floor(numCalendarDays / 7);

    // Potential days to add on to the number of full calendar
    // weeks. This will be adjusted by "finalAdjust"
    var remainderDays = numCalendarDays % 7;

    // Adjustments for start and end dates being on a weekend
    // ----------------------------
    // Start  at one because the same day should count as 1
    // but number of days between same day is 0 based on
    // arithmetic above.
    // Change this to 0 if you don't want end date inclusive...
    var finalAdjust = 1;
    var startDay = start.getUTCDay();
    var endDay = end.getUTCDay();
    // On a weekend, so adjust by subtracting 1
    if (isWeekendDay(startDay)) {
      finalAdjust--;
    }
    // On a weekend, so adjust by subtracting 1
    if (isWeekendDay(endDay)) {
      finalAdjust--;
    }
    // This accounts for subtracting an extra weekend when starting
    // at the beginning of a weekend (e.g. Saturday into Monday)
    // The end day cannot also be on a weekend based on week modular division (mod 7)
    if (startDay === SAT && remainderDays > 2) {
      finalAdjust--;
    }
    // ---------------------------

    // For every full calendar week there are 5 week days
    // Use that number with the remainderDays and finalAdjust above
    // to arrive at the answer.
    var numWeekDays = (5 * numWeeks) + remainderDays + finalAdjust;

    return numWeekDays;
  }

  // Test cases
  // Assume that the start and end dates are inclusive
  // 2020-01-01 to 2020-01-01 is one day
  // 2020-01-01 to 2020-01-02 is two days
  // ----------------------
  // A Wednesdday
  var start = new Date("2020-01-08");
  // A Saturday
  var end = new Date("2020-02-01");
  // Expected answer: 18
  console.log(numberWeekDays(start, end));

  // A Saturday
  start = new Date("2020-01-05");
  // A Monday
  end = new Date("2020-01-31");
  // Expected answer: 20
  console.log(numberWeekDays(start, end));

  // Weekday to weekday Tuesday to 
  start = new Date("2020-01-07");
  end = new Date("2020-01-16");
  // Expected: 8
  console.log(numberWeekDays(start, end));

  // Same week: Mon-Wed
  start = new Date("2020-01-06");
  end = new Date("2020-01-08");
  // Expected answer: 3
  console.log(numberWeekDays(start, end));

  // Same day
  start = new Date("2020-01-08");
  end = new Date("2020-01-08");
  // Expect: 1
  console.log(numberWeekDays(start, end));

  // Weekend only
  start = new Date("2020-01-04");
  end = new Date("2020-01-05");
  // Expect: 0;
  console.log(numberWeekDays(start, end));
  // ------------------
}());

As others have stated, a date library like moment is useful here because it gives you a lot of utility functions for working with dates and durations.