diff for same day (one UTC, one regular) gives 10800000

[mariusa]

Describe the bug
UTC diff for same day gives 10800000

let dayjs = require('dayjs')
let utc = require('dayjs/plugin/utc')
dayjs.extend(utc)

console.log('diff', dayjs.utc('2021-06-07').diff('2021-06-07', 'days')) //gives 10800000. Expected: 0 or maybe 1, if timezone difference
console.log('diff', dayjs.utc('2021-06-07').diff(dayjs.utc('2021-06-07'), 'days')) //gives 0, correct

Expected behavior
diff = 0 or maybe 1, if timezone difference

Information

• Day.js Version 1.8.27
• OS: Fedora
• Browser nodejs 12
• Time zone: GMT+3

[iamkun]

This should give you the correct result

dayjs.utc('2021-06-07').diff(dayjs.utc('2021-06-07'), 'days')

Cause you are comparing one UTC time with one local time above.

[mariusa]

Right, I've mentioned the 2nd line works properly.

But in the 1st case, should the diff be 0 or maybe 1, if timezone difference?
There can't be 10800000 days difference between same date in 2 different timezones.

[iamkun]

Apparently, there's a bug in calculating diff between two different timezones.

[iamkun]

Current workaround.

dayjs.utc('2021-06-07').local().diff('2021-06-07', 'days')) 
dayjs('2021-06-07').diff(dayjs.utc('2021-06-07').local(), 'days')) 

[iamkun]

fixed

[iamkun]

🎉 This issue has been resolved in version 1.8.33 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[justingolden21]

How is one supposed to calculate the difference between two timezones? Get the UTC string with format 'Z' and then parse int?

EDIT: got it with .utcOffset() / 60