How do you tell if a datetime is am or pm using luxon / moment?

Question

This:

import {DateTime} from "luxon";

[
   "2022-05-30T11:00:00Z",
   "2022-05-30T11:00:00+01:00",
   "2022-05-30T11:00:00-01:00",
].map(raw => {
   var sysTime = DateTime.fromISO(raw);
   var amPm = sysTime.hour < 12 ? "am" : "pm";
   console.log(`${raw}: ${amPm}`);
});

Emits this:

2022-05-30T11:00:00Z: pm
2022-05-30T11:00:00+01:00: pm
2022-05-30T11:00:00-01:00: pm

Which is clearly wrong.

Yes, it is wrong, because 2022-05-30T11:00:00+01:00 is not pm in that timezone.

Since luxon automatically stores SystemZone, you have to explicitly convert it to correct timezone, if you happen to know what it is, for example:

[
   "2022-05-30T11:00:00Z",
   "2022-05-30T11:00:00+01:00",
   "2022-05-30T11:00:00-01:00",
].map(raw => {
   var sysTime = DateTime.fromISO(raw);
   var realTime = sysTime.setZone('UTC+1'); // <---- explicit
   var amPm = realTime.hour < 12 ? "am" : "pm";
   console.log(`${raw}: ${amPm}`);
});

Emits this:

2022-05-30T11:00:00Z: pm <---- still wrong
2022-05-30T11:00:00+01:00: am <--- correct
2022-05-30T11:00:00-01:00: pm

So, what's the right way to do this?

...and to be clear, I'm not trying to parse these date times without a timezone, I'm trying to parse them in a way that preserves the "UTC+X" timezone that is in the raw date string.

Is that possible?

Answer 1

use: setZone: true in fromISO.

import {DateTime} from "luxon";

[
   "2022-05-30T11:00:00Z",
   "2022-05-30T11:00:00+01:00",
   "2022-05-30T11:00:00-01:00",
].map(raw => {
   var sysTime = DateTime.fromISO(raw, {setZone: true});
   var amPm = sysTime.hour < 12 ? "am" : "pm";
   console.log(`${raw}: ${amPm}`);
});