Creating an array of dates between 2 dates

Question

I have 2 dates: startdate and enddate. End date is always a day less than the startdate. So if my start day is 19th, the end date would be on the 18th of next month.

I am trying to create an array of number of days in between the 2 dates. (It goes from 19th to 18th and then 18th to 18th of every month to calculate the difference)

Example

8/19/2018 - 9/18/2018 = 30 days

9/18/2018 - 10/18/2019 = 30 days

10/18/2018 - 11/18/2018 = 31 days

array = [30,30,31]

I am using the following code to calculate days difference between the dates.

  function daysBetweenArrears (date1, date2){

         date1.setDate(date1.getDate() );
         date2.setDate(date2.getDate() - 1);
         var Diff = Math.abs(date2.getTime() - date1.getTime());
         var TimeDifference = Math.round(Diff / (1000 * 3600 * 24));
         return TimeDifference;
    }

The following code for creating the array

  if (document.getElementById("endDate"))
             y = document.getElementById("endDate").value;
          if (document.getElementById("startDate"))
             z = document.getElementById("startDate").value;

var dateArr = getDateArray(z, y);
     var dayCountArr = "";
     var b = [];

     for (var x = 0; x < dateArr.length-1; x++)
     {
         dayCountArr += daysBetweenArrears(dateArr[x], dateArr[x+1], ",");
         b.push(daysBetweenArrears(dateArr[x], dateArr[x+1]));
     }

The issue is that when i set the date as following, it is giving me incorrect output. The problem is that it is setting the dates incorrectly whenever it goes to the next month. I am not sure what i am doing wrong here. Any help is greatly appreciated. Thank you.

date2.setDate(date2.getDate() - 1);

Possible duplicate of Difference between dates in JavaScript — Herohtar
– Herohtar, Commented Oct 17, 2018 at 21:06
Your example dates are confusing because they don't follow what you said. You have some dates that are more than a year apart. — Herohtar
– Herohtar, Commented Oct 17, 2018 at 21:08
@Herohtar How are they a year apart? It's only going up by 3 months. — ace23
– ace23, Commented Oct 18, 2018 at 13:11
Take another look. You have 8/19/2018 - 9/18/2019, etc. The years are different. — Herohtar
– Herohtar, Commented Oct 18, 2018 at 14:23

Alex G · Accepted Answer · 2018-10-19 07:26:04Z

1

You can do this using moment. Hope this helps.

const start = "8/19/2018";
const end = "11/18/2018 ";

const dates = [];

const mstart = moment(new Date(start));
const mend = moment(new Date(end));

for (let i = 0; mstart < mend ; i++) {

    const daysInMonth = mstart.daysInMonth() + (i === 0 ? -1 : 0);

    dates.push(daysInMonth);

    mstart.add(1, 'M');
}

console.log(dates);

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.2/moment.min.js"></script>

edited Oct 19, 2018 at 7:26

answered Oct 18, 2018 at 14:35

Alex G

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13 Comments

ace23 Over a year ago

The first number in that array should be 30 instead of 31 because the date is going from 19th to 18th.

Alex G Over a year ago

@ace23 updated answer. Let me know if this helps you.

ace23 Over a year ago

I tried this. I t works but for some reason it crashes if i try to look at the date range and i am also not able to add any if else statements!

Alex G Over a year ago

@ace23 Could you give an example of what you tried? What do you mean "look at the date range"?

ace23 Over a year ago

date range = 8/19/2018 , 9/19/2018,10/19/2019...I tried adding if else condition to this but the code crashes.

|

Pengcheng · Accepted Answer · 2018-10-17 21:34:11Z

0

You can update your function daysBetweenArrears

const daysBetweenArrears = (date1, date2) => {
  const time1 = new Date(date1).getTime();
  const time2 = new Date(date2).getTime();
  const diff = Math.abs(time2 - time1);
  return Math.round(diff/(1000*60*60*24));
};

console.log(daysBetweenArrears('8/18/2018', '9/18/2018'));
console.log(daysBetweenArrears('6/18/2018', '7/18/2018'));

answered Oct 17, 2018 at 21:34

Pengcheng

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