timezone-boundary-builder VS js-joda

They don't really bother me. They aren't AI spam, and some folks may enjoy them. It's pretty easy to not click on a link, for me.

TZ are a fun project. I found that it's difficult to translate a long/lat into a TZ ID, so I wrote this[0].

Works a charm. It's based on the Timezone Boundary Builder[1].

[0] https://github.com/LittleGreenViper/LGV_TZ_Lookup

[1] https://github.com/evansiroky/timezone-boundary-builder

I wrote a tutorial on SpatiaLite here: https://datasette.io/tutorials/spatialite - "Building a location to time zone API with SpatiaLite"

It shows how to use SpatiaLite + Datasette to build an API that can tell you what timezone a latitude/longitude point is in, using data derived from OpenStreetMap via https://github.com/evansiroky/timezone-boundary-builder

Here's a demo: https://timezones.datasette.io/timezones/by_point?longitude=... - add ".json" to the URL for the JSON output.

I have never had an opportunity to deploy this tool, but here's a program for generating a TZ shapefile from OpenStreetMap data:

https://github.com/evansiroky/timezone-boundary-builder

In principle a calendar program could use its output to perform GIS lookups of locations then use the tzinfo DB to get the correct timezone at the given location and specified time.

You could ask google. Amazon or Microsoft probably offer similar APIs. Or you can do it yourself. It's a very complicated topic, though.

There is a separate timezone boundary builder which maps geography to timezones using a shapefile, and the shapefile is >35MB uncompressed. By comparison the latest tzdata is 1.2M uncompressed.

js-joda

So first, a simple example of how this works. Using our "What is your birthday" example, we can mock up this code. Note: I'm using TypeScript because it enforces the concepts at compile time, but the JsJoda library itself enforces the concepts at runtime so that we get the best of both.

Dealing with human dates is non-trivial thanks to localization. The easiest thing to do is to start with something zone agnostic (like UTC or epoch) do your date calculation, and then shift that into the locale you want. date-fns is fine for basic date math, but if you want something more robust, with a more cohesive API, I'd recommend js-joda.

How come the js-joda library is never mentioned in discussions about javascript date/time libraries? its API is perfect and it has been around forever. but instead the community seems to keep inventing more and more new datetime libraries. i don't understand why js-joda seems to be ignored

https://js-joda.github.io/js-joda/

I've been getting by with js joda. Temporal is a welcome addition.

Support for the domain models LocalDate, LocalDateTime, ZonedDateTime, Instant, Duration and Period. Also, supports IANA timezone, adding the plugin @js-joda/timezone you'll have access to the IANA timezone database with all the timezones available.