alt Hacker NewsThe only time you need local dates is for scheduling. Stuff like “Report KPIs for each shift. Shifts start at 8:00 local time.”, or “send this report every day at 10:00 local time”, or “this recurring meeting was created by user X while they were in TimeZone Z, make sure meetings follow DST”.
Outside of scheduling UTC is the way.
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The pathological case with scheduling is: It's 2015. You live in NYC. Your pal in Santiago, Chile says "hey next time you're here let's hang out." You say "great, I have a business trip there next April. Let's have dinner at 7pm on the 15th." They agree. You enter it into your calendar. If you store it as UTC, you're going to show up to dinner at the wrong time—the DST rules changed in between when you talked and when you expected dinner to happen. If you'd stored it as a local time with tzdb name America/Santiago you'd be there at the correct local time.
> Report KPIs for each shift. Shifts start at 8:00 local time.
To represent this you probably don't want a local date. Plain times [1] and plain date/times [2] are a better fit.
[1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...
[2]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...