dayjs is not converting timezones properly

Question

I'm trying to convert a date from my local time (Taipei UTC+8) to Los Angeles ( UTC-7) however dayjs conversion seems to be completely off :

dayjs("2020-09-21 20:30").tz("Asia/Taipei")

this results in Tue Sep 22 2020 05:30:00 GMT-0400 (Eastern Daylight Time) but it should have been Mon Sep 21 2020 02:30:00 GMT-0400 (Eastern Daylight Time)

any idea what's going on?

Wehrle

Please read the Day.js documentation about string parsing and "Parsing in Zone". – Lanti

Answer 1

I fixed using utc first and then format on local timezone

import dayjs from 'dayjs'
import utc from 'dayjs/plugin/utc'
import tz from 'dayjs/plugin/timezone'

dayjs.extend(utc)
dayjs.extend(tz)

const timeZone = dayjs.tz.guess()
dayjs.utc(dateToConvert).tz(timeZone)

Baccalaureate

THIS is the fix. – Skyscape

What is utcDate? – Kerchief

@Kerchief date which should be converted to desired tz – Baccalaureate

Answer 2

try this:

dayjs.extend(utc)
dayjs.extend(timezone)
dayjs("2020-09-21 20:30").tz("Asia/Taipei")

Herra

Answer 3

import dayjs from 'dayjs'
import utc from 'dayjs/plugin/utc'
import tz from 'dayjs/plugin/timezone'

dayjs.extend(utc)
dayjs.extend(tz)    

dayjs("2020-09-21 20:30").tz("Asia/Taipei").local().toDate();

dayjs("2020-09-21 20:30").tz("Asia/Taipei").local().toDate().toLocaleString();

.toString() and .toISOString() seem to always print the original date, before the timezone conversion, which may cause some confusion. toDate().toLocaleString() works.

Calenture

This is the real answer. By not setting .local().toDate() it does not convert the date to the selected timezone. Really strange approach they took with that. – Flat

Answer 4

I've fixed it by adding .local() after dayjs("2020-09-21 20:30").tz("Asia/Taipei").local()

Wehrle

Answer 5

I'm using latest version of dayjs - 1.11.1 and react native v0.66.4. When I write:

dayjs("2020-09-21 20:30").tz("Asia/Taipei")

I get null as result. Does anybody have that problem?

Immovable

Did you solve this ? – Ferdy

check this github.com/iamkun/dayjs/issues/1377#issuecomment-775941749 – Solicitor

Answer 6

Without including any plugin like utc, timezone you can easily format utc date and pass it into dayjs like below:

const utcTimestamp = 1668414677538;
const utcFormat = dayjs(utcTimestamp).format('YYYY-MM-DDTHH:mm:ss+00:00');
console.log(dayjs(utcFormat).format('DD MMM, hh:mm a'));

It will do the trick

Chancelor