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Pikaday: A friendly guide to front-end date pickers

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286 points mnemonet | 6 comments | 11 Nov 25 14:58 UTC | HN request time: 0s | source | bottom
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Muromec ◴[11 Nov 25 21:28 UTC] No.45893136[source]▶
After dealing with datepickers for (checks notes) two decades, my best advice is to use the damn input type text with a placeholder showing a format, then saving it as a string in whatever that ISO that makes sense is called.

Everything else is asking for endless trouble and pain with browsers, a11y, locales and what not. Also, may the God allmerciful save you from the cancer that custom components are, let whoever invented this wipe his ass with fiberglass insulation for the end of times.

Don't get fancy and you will not fall down 10 rabbit holes that datepickers are.

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mattmanser ◴[11 Nov 25 23:07 UTC] No.45894154[source]▶
This should be called bad advice about dates every developer should avoid.

ISO 8601 does NOT work with future dates. It does not work with cross border appointment booking.

ISO 8601 only works for dates and times that have already happened.

I have 20 years, have worked with apps that relied on future and past dates, have used date pickers since 2005 and would still hesitate to give advice about what is an incredibly complex problem that entirely depends on your use case.

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Telaneo ◴[12 Nov 25 01:59 UTC] No.45895541[source]▶
> ISO 8601 does NOT work with future dates. It does not work with cross border appointment booking.

Why is this the case? Is it some time zone shenanigans?

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mattmanser ◴[12 Nov 25 08:04 UTC] No.45897511[source]▶
Timezones change, more frequently than you realize. Some countries even used to change when summer time started regularly. It's got better than it used to be afaik.

Also you need to take into account where the user is going to be. With future dates, time is relative. So at the very least you often need the time + the timezone of the location.

Book me a table at 8, means book me a table in Berlin time at 8, not in San Francisco time at 8.

Same with displaying future dates, you need the context of where.

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Philip-J-Fry ◴[12 Nov 25 10:22 UTC] No.45898479[source]▶
This is nothing to do with ISO 8601 though.

You can represent time zones with that format. So long as you have a source time zone, target time zone and tzdata you can convert any time accounting for all the particularities of any particular zone.

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1. iso1631 ◴[12 Nov 25 13:40 UTC] No.45900037[source]▶
ISO 8601 timezone only allows an offset. You can't encode "04:00 in Cairo on 13th November 2036" as there's no way to know what UTC offset Cairo will have in October 31st 2036.

> 2036-11-13 04:00:00 Africa/Cairo

Is fine

> 2036-11-13 04:00:00 +0200

Is not, as the rules around moving from +3 to +2 may well have changed by them.

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2. seanhunter ◴[12 Nov 25 14:47 UTC] No.45900888[source]▶
That’s got literally nothing to do with ISO 8601 though. Times are just hard and there’s no way to know the future with any kind of certainty. In this case there’s no way of knowing whether Egypt will by 2036 have changed their timezone or added or eliminated DST. Nothing to do with ISO 8601, just the world is uncertain.

Take the UK for another example. The daylight savings dates are actually set by act of parliament. Although they always have fallen in the pattern that everyone knows, for dates in future years beyond the ones they have already set, they could hypothetically (if you want to be literal-minded about it) change the law to make DST happen on absolutely any day of the year or not at all.

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3. Muromec ◴[12 Nov 25 15:40 UTC] No.45901517[source]▶
Are you scheduling a restaurant reservation for 2036? Will it change from 09 to 10 in the morning depending on DST?

Sure, we cant know what unix date it resolves to, but it doesn't matter, because future dates are more of a contract intentionally bound to context that is subject to change.

4. iso1631 ◴[12 Nov 25 15:49 UTC] No.45901628[source]▶
ISO 8601 only allows timezones as offsets, not as locations.

If it allowed "Africa/Cairo" instead of "+0200" that would be fine.

> they could hypothetically (if you want to be literal-minded about it) change the law to make DST happen on absolutely any day of the year or not at all.

That's the whole point - that's why you store future date/times with the location, not the offset, and not in UTC

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5. phiresky ◴[12 Nov 25 16:41 UTC] No.45902295{3}[source]▶
There's an extension to ISO8601 that fixes this and is starting to become supported in libraries:

    2019-12-23T12:00:00-02:00[America/Sao_Paulo]
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...
6. jrochkind1 ◴[12 Nov 25 18:00 UTC] No.45903418[source]▶
The fact that ISO8601 does not store time zones (only fixed UTC offsets, which is not the same thing) obviously has something to do with ISO8601. I'm not sure what you're going on about?