Added deltaZone in the equation when calculating diff

[naulacambra]

I've looked into momentjs code, and tried to understand why method dayjs().diff() was returning different values than moment().diff() when the unit was day. Happens that momentjs uses the offset of each element to calculate hour zone difference, and adds it to the equation.

I've had to add the utcOffset() method in the core (where the diff() method is), but only the get version.

This should resolve #384

[codecov-io]

Codecov Report

Merging #452 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #452   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          52     52           
  Lines         467    469    +2     
  Branches       72     72           
=====================================
+ Hits          467    469    +2

Impacted Files	Coverage Δ
src/constant.js	100% <ø> (ø)	⬆️
src/index.js	100% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 97a6088...c9ca021. Read the comment docs.

[iamkun]

Oh I see, nice catch.

Besides, I think we could add utcOffset as a public api to our user.

Docs and test should be included.

How do you think? Or I could make a pr if I got some time.

[iamkun]

PS, could you please re-open a new pr to merge your code to our dev branch.

It might good to have a dev branch waiting for next release.

[naulacambra]

Besides, I think we could add utcOffset as a public api to our user.

Sure, I'll add the utcOffset documentation and tests

PS, could you please re-open a new pr to merge your code to our dev branch.

Ok, i'll close this PR and open a new one

[iamkun]

Thanks