scala-js/scala-js

Scala.js, the Scala to JavaScript compiler

Sébastien Doeraene

@sjrd

It worked by chance before.

Michael Pilquist

@mpilquist

yep

aappddeevv

@aappddeevv

I need to pass an async iterator to a js API. Has anyone found any patterns in scala.js that can help interface to this type of requirement? I need this server-side/node.js so I'm wondering if a package like https://github.com/achingbrain/it could help with interfacing to scala.js.

Iurii Malchenko

@yurique

does anyone know if it possible to enable a plugin only for .js project when using crossProject(…).crossType(Pure)? (for the ScalaJSJUnitPlugin)

Sébastien Doeraene

@sjrd

.jsConfigure(_.enablePlugins(...))

Iurii Malchenko

@yurique

Thank you! (how did I miss that?.. 🤔)

Eric K Richardson

@ekrich

Is there a parallel one for Scala Native? I couldn't find one.

Sébastien Doeraene

@sjrd

There should be .nativeConfigure

Eric K Richardson

@ekrich

If it is there, it doesn't seem visible.

Sébastien Doeraene

@sjrd

It's defined here, though: https://github.com/portable-scala/sbt-crossproject/blob/e1ec68f1321a313abeb27c7bb7f7bca1a5ac9d91/sbt-scala-native-crossproject/src/main/scala/scalanativecrossproject/ScalaNativeCrossPlugin.scala#L23-L24

If it's in a Build.scala, it might need an explicit import of the autoImport._ members.

Victor Hiairrassary

@vhiairrassary

Hi there :wave: I have a couple of open pull requests for different repositories around Scala.js. Ideally, I would love to get feedbacks & be able to participate in the community. (feel free to discard this comment if it is not in the correct conversation)
scalajs-bundler:

Webpack 5 support (scalacenter/scalajs-bundler#390)
Fix webpack-dev-server logs w/ sbt 1.4.x (scalacenter/scalajs-bundler#391)
Sync NPM lock file (scalacenter/scalajs-bundler#392)
Use GitHub Actions, following Travis CI announcements (scalacenter/scalajs-bundler#393)
scala-js-dom:
Add ParentNode.replaceChildren (scala-js/scala-js-dom#439)
Add onwheel (scala-js/scala-js-dom#436)

Anyway, thank you to all the people involved in this project and for the time spent!

1 reply

Sébastien Doeraene

@sjrd

Hi @vhiairrassary. Sorry we haven't been responsive so far. I don't put my head into scalajs-bundler or scalajs-dom very often. I'll try to allocate time this week to look at those.

1 reply

Eric K Richardson

@ekrich

@sjrd I was using build.sbt and it is there and works - for some reason Metals does not find it. With the 1.0.0 plugin, everything is like magic - so used to imports, enables, etc.

Andreane Schultz

@Andreane56_gitlab

Thanks yo for posting that it could be just the in thing to give inspiration to someone who need it! Keep up the great work. https://www.myaarpmedicare.review/

Dave Smith

@davesmith00000

Hi @sjrd - I was wondering if I could ask your opinion: I'm going to pass a potentially large nested case class structure (also contains ADTs but could possibly be factored out if that helps) to a Web Worker. What do you think is the most efficient/performant way to convert the structure to JS objects and back? (worker interface takes js.Any I believe)
I'm currently hand rolling it all using js.Dynamic.literal() to produce a crude codec, which is boring but ok, but I'm wondering about the allocate costs of such a thing (?) and thought I'd see if there was a simpler/better solution? I would be doing this 60 times per second...

Sébastien Doeraene

@sjrd

I don't really have a good suggestion. It's either literal()s, or serializing a to an ArrayBuffer. An ArrayBuffer would probably be quicker to allocate, but you have to pay the price of serialization and deserialization. Only measuring can decide which is truly better.

Anton Sviridov

@keynmol

we don't use web workers, but for lots of small objects we do use literals, but our data structures are small and not recursive, so hand cranking those codecs is simple.

In a different usecase with a huge recursive case class I'm using upickle, but the size of the result doesn't please me - so I want to give boopickle a go, which should improve the serialisation roundtrip. I wonder if it can benefit from 1.4.0 typed array improvements?

Dave Smith

@davesmith00000

Thanks both, good to know. 👍

Anton Sviridov

@keynmol

If you do get round to benchmarking - let us know how it goes :)

Dave Smith

@davesmith00000

I will, though don't hold your breath, I'm still in the "gosh I hope this works at all" stage. 😉

Andriy Plokhotnyuk

@plokhotnyuk

@davesmith00000 @keynmol Here are results of parsing and serialization of different data types and message samples in browsers using different JSON libraries, including uPickle. Sources of benchmarks are here, and instructions how to build and run them are here. Feel free to try with your data structures and codecs.

Dave Smith

@davesmith00000

That's a great page, thanks! One slight wrinkle is that I'm trying to avoid macro based systems at the moment since I'm targeting Scala 2 & 3, so I'd need to be carefully about which libraries I used. The other thing is that I'm running on an assumption (always dangerous...) that although full serialisation would be easier (much!), it's probably heavier than a conversion to a native JS objects - no parsing for one thing.

Anton Sviridov

@keynmol

damn @plokhotnyuk that's awesome. I don't have no-macro requirements as Dave does, so I'll check out everything on that page and see how it works out for my particular usecase

Andriy Plokhotnyuk

@plokhotnyuk

@keynmol Cool! Any you feedback will be greatly appreciated! Also, if you can give a description of your usecase please share it in the project chat.

Sébastien Doeraene

@sjrd

All interested: should we create a gitter8 template for Scala.js? And if yes, what should it contain? scala-js/scala-js#4390

Martijn

@martijnhoekstra:matrix.org

[m]

I would love a g8 template that has a shared jvm/js lib project and a js web project, if at all possible cross-building with scala3

Anton Sviridov

@keynmol

I think it's a rad idea, so I put a few ideas on the issue

Hanns Holger Rutz

@Sciss

My understanding is that in 1.4 Array[Byte] will be represented by a typed-array, like Int8Array? Then, if I have an ArrayBuffer, is there a straight forward way to get an Array[Byte] without copying? Like is there a better way than doing new Int8Array(ab).toArray[Byte] (is that even correct?)?

Tobias Schlatter

@gzm0

@Sciss there isn't a way to do this without copying.

Hanns Holger Rutz

@Sciss

ok. is toArray[Byte] correct then?

Tobias Schlatter

@gzm0

Yes, if you need an Array[Byte]. Alternatively, if you use ByteBuffer, you can avoid copying.

Uh, actually, I don't think you need the type parameter. Lemme check.

Simply toArray is sufficient: http://www.scala-js.org/api/scalajs-library/latest/scala/scalajs/js/typedarray/package$$TA2AB.html

(btw. all of this is not new in 1.4.0)

Hanns Holger Rutz

@Sciss

ok, thanks. Can't use ByteBuffer in this case.

Tobias Schlatter

@gzm0

This lets you make a ByteBuffer (without copying): http://www.scala-js.org/api/scalajs-library/latest/scala/scalajs/js/typedarray/TypedArrayBuffer$.html

Hanns Holger Rutz

@Sciss

cheers

unarist

@unarist

I wonder if supporting Dynamic module loading in sjs 1.4 also means js.import() is compatible with fullLinkJS...

Sébastien Doeraene

@sjrd

It's compatible. But as soon as you choose to emit ES modules, the sbt plugin will deactivate Closure.

unarist

@unarist

oh, I forgot that sjs deactivate closure with ESM outputs

So it means less optimized for size or performance than CJS outputs?

unarist

@unarist

(I've used js.Function to wrap import()calls to use it in CJS outputs though)

Sébastien Doeraene

@sjrd

It's less optimized for size. But it's typically more performant.

It seems ES modules are faster than CommonJS modules, which are themselves faster than scripts.

unarist

@unarist

Oh really? I will take a look later. thanks!

Iurii Malchenko

@yurique

Hi everyone.
Following the footsteps of @lolgab (https://github.com/lolgab/scalajs-snowpack-example — kudos!) I’ve made a more complete example of using the Snowpack with Scala.js: https://github.com/yurique/laminar-snowpack-example

Tobias Schlatter

@gzm0

@yurique @lolgab in case you have any experience with snowpack incremental build times combined with module splitting in SmallestModules mode, I'd love your input on #4327.

happyhua

@happyhua

Hi here, I have a question about using scala-js. Can it be used together with gwt?
If not, what is the obstacle here? Scala self is compiled in java byte code, and fully compatible with Java.
Would it not be nice that scala-js can also support java-2-javascript compilation?

Anton Sviridov

@keynmol

Scala.js actually compiles files down to its own internal representation (.sjsir), from which it generates JavaScript - not from the JVM-compatible bytecode directly.

There's some architectural notes from this excellent blogpost: https://www.scala-lang.org/2020/11/03/scalajs-for-scala-3.html which also hints at the ability to compile Java to .sjsir, but I can't imagine it's a priority

1 reply

Where communities thrive

People

Repo info

Activity