Comment by josephg
Are any other languages more sane with this stuff? Because I've also been to this particular corner of hell. Also in a web app.
But - wouldn't this be just as horrible in Go or Rust or any other language? (Or god forbid, C?) Are there better timezone APIs in other languages than what you can find in NPM that make these problems any easier to deal with?
Elixir handles all of this pretty well, for example differentiating between Date, Time, NaiveDateTime (a date and time), and DateTime (a date and time in a particular timezone). The Timex library is a great improvement too.
JS has libraries that make the problem easier too. Though you'll never find a magic library that makes all the complexity disappear, because at the end of the day, you do need to tell the computer whether you mean 7 pm on the wall clock of where the users happen to be, 7 pm on a specific date in a specific time zone, etc. and doing math between dates is inherently complex with e.g. daylight savings changes. You might end up creating a datetime that doesn't exist (which Elixir handles well).