[lomnakkus]

Right, but the JS and JVM runtimes have quite different behavior. And I'm willing to bet that implementing something as non-trivial as java.time again in Scala(.js) will end up causing quite a few bugs because they aren't identical.

That's why I'd rather have a single implementation for anything non-trivial and just retarget that to each backend using more low-level primitives. After all you're using a different language -- using a different date/time API shouldn't be much of a problem.

[justthistime_]

Yeah, inventing an API and implementation of a date/time/calendar library from scratch without an existing spec, implementation, tests or experience will surely be totally bug-free.

[lomnakkus]

I'm not sure why you're being sarcastic.

I'm not saying it'll be bug-free. My point is that it'll have exactly the same bugs on either platform. This may be preferable to having different bugs on different platforms.

[justthistime_]

Same bugs on different platforms are extremely hard to find.

Different bugs on different platforms are like an early Christmas present:

You don't even need to write tests which include your "expectations" of the result anymore.

Just call the code with randomized inputs for both platforms, and if there is a difference, you found a bug.

[lomnakkus]

That's a good point. As a (shim) library developer I think I might agree -- because it would perhaps be easier to find bugs in my library -- as an application developer I wouldn't because I would have to find different workarounds for different bugs.