Find difference in days between two integers representing dates in the format "yyyymmdd" using math skills with javascript

Question

Hey how can you find the number of days difference in javascript between two dates with a "yyyymmdd" format?

For instance 20210206 - 20210825 will return 619, however these dates are actually only 200 days apart.

Also, I have to do with the dates as just integers. I don't have access to any special date functions.

Is there a math genius out there who knows what to do?

Also, I have to do with the dates as just integers. I don't have access to any special date functions. — Michael Orr, Aug 25 '21 at 18:23
Does this answer your question? [How do I get the number of days between two dates in JavaScript?](https://stackoverflow.com/questions/542938/how-do-i-get-the-number-of-days-between-two-dates-in-javascript) — ponury-kostek, Aug 25 '21 at 18:24
What about the date functions built into the javascript language? — Joel Coehoorn, Aug 25 '21 at 18:24
Another one https://stackoverflow.com/questions/3224834/get-difference-between-2-dates-in-javascript — ponury-kostek, Aug 25 '21 at 18:25
No that doesn't help. I have to use straight up math skills. They aren't actually dates, they are just integers representing dates. — Michael Orr, Aug 25 '21 at 18:28
You need a way to **substr()** to return the value in a Date format. https://www.w3schools.com/jsref/jsref_substr.asp — Patfreeze, Aug 25 '21 at 18:29
Yeah, I guess if there is a way to convert the numbers into an actual Date object, that could help. — Michael Orr, Aug 25 '21 at 18:31
https://stackoverflow.com/questions/10607935/convert-returned-string-yyyymmdd-to-date — ponury-kostek, Aug 25 '21 at 18:32

Spectric · Accepted Answer · 2021-08-25T18:35:37.087

0

Use String.substring to split the string into 3 parts (year, month, date) and pass them as parameters in the Date object, then subtract and divide by 86400000:

function convertToDate(s){
  return new Date(s.substring(0, 4) - 1, s.substring(4, 6) -1, s.substring(6));
}
const first = "20210206";
const second = "20210825";
const diff = Math.floor(Math.abs((convertToDate(first) - convertToDate(second)) / 86400000))
console.log(diff)

edited Aug 25 '21 at 18:35

answered Aug 25 '21 at 18:33

Spectric

30,714
6
20
43

Yes, this is exactly what I'm looking for. Thanks. – Michael Orr Aug 25 '21 at 18:35
1

There is a time wait before it will allow me to accept, haha. – Michael Orr Aug 25 '21 at 18:35

Find difference in days between two integers representing dates in the format "yyyymmdd" using math skills with javascript

1 Answers1