Calling tz() overrides locale

[wang-yikai]

Running
dayjs('2020-01-08T15:14:59.741774+00:00') .locale('es') .tz('America/New_York') .format('LLL')
gives January 8, 2020 10:14 AM instead of 8 de enero de 2020 10:14.

However, switching the order of locale and tz, e.g.
dayjs('2020-01-08T15:14:59.741774+00:00') .tz('America/New_York') .locale('es') .format('LLL')
gives the correct result of 8 de enero de 2020 10:14.

I believe this is the result of the following line of code, which overrides the current locale:

dayjs/src/plugin/timezone/index.js

Line 98 in a9d7d03

const target = date.toLocaleString('en-US', { timeZone: timezone })

This is the intended behavior or is it something to be fixed to support the provided locale?

[ohsory1324]

I think this issue(#2248) should be checked.

[timsand]

I'm encountering this issue as well. For me, it seems that the locale weekStart property is ignored if it also has a timezone.

Example:

const dayjs = require('dayjs');
const utc = require('dayjs/plugin/utc');
const timezone = require('dayjs/plugin/timezone');

dayjs.extend(utc);
dayjs.extend(timezone);

const now = '08/22/2023';

const withLocality = dayjs(now).locale({
  name: 'locale_only',
  weekStart: 3,
});
const withLocalityAndTimezone = dayjs(now).tz('America/New_York').locale({
  name: 'locale_and_tz',
  weekStart: 3,
});
const timezoneOnly = dayjs(now).tz('America/New_York');

const a = withLocality.startOf('w'); // returns the expected value of 2023-08-16
const b = withLocalityAndTimezone.startOf('w'); // returns the unexpected value of 2023-08-20
const c = timezoneOnly.startOf('w'); // returns the expected value of 2023-08-20

I believe that the line described above with target is actually OK - when that target is passed to d though it loses the locality context.

I created a PR here with what I think may help fix this (unless this is intended behavior).

[xg4]

dayjs/src/plugin/timezone/index.js

Line 100 in a9d7d03

let ins = d(target).$set(MS, this.$ms)

The .tz method creates a new dayjs object but does not inherit previous properties, causing the language setting to be lost.

[github-actions]

🎉 This issue has been resolved in version 1.11.10 🎉

The release is available on:

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

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