DST change in Egypt is not taken into account (GMT+2 => GMT+3)

[vsalahkar]

Describe the bug
Egypt has announced that they're bringing back DST starting from the last Friday of April this year:
→ https://egyptianstreets.com/2023/03/01/egypt-brings-daylight-saving-time-back/

We've noticed that the luxon package does not return the correct hour for dates after April 28th

To Reproduce
DateTime.fromISO('2023-05-24 18:20:00+00', { zone: Africa/Cairo })

Actual vs Expected behavior

• It will return 2023-05-24 20:20:00 (GMT+2)
• It should return 2023-05-24 21:20:00 (GMT+3)

Desktop (please complete the following information):

• OS: MacOS
• Browser Chrome Version 111.0.5563.146
• Luxon version 3.3.0
• Your timezone Europe/Paris

Additional context
Moment timezone did the update, see this PR.

Thanks four your answers.

[diesieben07]

Luxon uses the Browser's time zone data via the Intl API. If this data is not correct, you'll have to report it to the respective browsers.

Edit: You can check if your browser has the correct data with the following code:

let date = new Date(Date.parse('2023-05-24 18:20:00+00'));
let dtf = new Intl.DateTimeFormat('en', {dateStyle: 'long', timeStyle: 'long', timeZone: 'Africa/Cairo'});
console.log(dtf.format(date));

Chrome 111 does indeed not have the correct data (yet).

[vsalahkar]

Luxon uses the Browser's time zone data via the Intl API. If this data is not correct, you'll have to report it to the respective browsers.

Edit: You can check if your browser has the correct data with the following code:

let date = new Date(Date.parse('2023-05-24 18:20:00+00'));
let dtf = new Intl.DateTimeFormat('en', {dateStyle: 'long', timeStyle: 'long', timeZone: 'Africa/Cairo'});
console.log(dtf.format(date));

Chrome 111 does indeed not have the correct data (yet).

Thanks for your quick answer @diesieben07!

Does it mean every user using my app with any browser must have an up-to-date browser?

It doesn't look scalable to be honest 😅

I'm wondering if I should not switch back to moment-timezone that looks more reliable.

[diesieben07]

If you want up to date TZ data then yes, the browser must be up to date.
The problem with using moment-timezone (or other libraries that ship their own TZ data, like https://formatjs.io/docs/polyfills/intl-datetimeformat/) is that you have to ship the entire TZ database to the client, which is also "not scalable".

[icambron]

Yeah, updating your software to include new TZ data every time any zone in the world changes is not a good solution. I recommend relying on the platform.

But, of course, you do you.