scala-js/scala-js

Scala.js, the Scala to JavaScript compiler

Tobias Schlatter

@gzm0

Ah, that would be nice.

Good point. We have done this with very old scala versions.

So, how many screens of IR cleaner report are left?

Sébastien Doeraene

@sjrd

In one of my branches, I'm down to 2000 errors IIRC :sweat_smile:

(usually they get fixed in the dozens at a time, though)

Greg Fagan

@gregfagan

Hello, I'm new to scala coming from a typescript/react background. Was trying to get scalajs-react imported to my project after following the scalajs hello world tutorial, but it looks like scalajs-react hasn't been updated for scalajs 1.0 yet. I changed my scalajs dependency version to 0.6.32, but it looks like scalajs-react is still trying to import a version for sjs1:

[error] (update) sbt.librarymanagement.ResolveException: Error downloading com.github.japgolly.scalajs-react:core_sjs1_2.13:1.6.0

can anyone help? sorry I do not understand very much about scala or sbt yet

trepidacious

@trepidacious

What's a good, simple, light logging library for scala and scala-js 1.0?

@gregfagan If you're running sbt interactively, have you run reload?

Greg Fagan

@gregfagan

yes

this is my plugins.sbt:

addSbtPlugin("org.scala-js" % "sbt-scalajs" % "0.6.32")
addSbtPlugin("ch.epfl.scala" % "sbt-scalajs-bundler" % "0.17.0")

and this is build.sbt:

import Dependencies._

enablePlugins(ScalaJSPlugin)
enablePlugins(ScalaJSBundlerPlugin)

ThisBuild / scalaVersion := "2.13.1"
ThisBuild / version := "0.1.0-SNAPSHOT"
ThisBuild / organization := "com.example"
ThisBuild / organizationName := "example"

lazy val root = (project in file("."))
  .settings(
    name := "hello",
    libraryDependencies += scalaTest % Test,
    libraryDependencies += "org.scala-js" %%% "scalajs-dom" % "1.0.0",
    libraryDependencies += "com.github.japgolly.scalajs-react" %%% "core" % "1.6.0"
  )

npmDependencies in Compile ++= Seq(
  "react" -> "16.13.1",
  "react-dom" -> "16.13.1"
)

scalaJSUseMainModuleInitializer := true

Tobias Schlatter

@gzm0

You are using the wrong bundler version.

https://scalacenter.github.io/scalajs-bundler/

You need addSbtPlugin("ch.epfl.scala" % "sbt-scalajs-bundler-sjs06" % "0.17.0")

Greg Fagan

@gregfagan

thank you!!

are there other view libraries that scalajs developers prefer? I was looking at react because that's what I'm familiar with, but maybe the community uses something else. Ideally with declarative UI semantics

trepidacious

@trepidacious

I've enjoyed using React, slinky is a very good alternative to scalajs-react as well

Oh also, slinky is available for scalajs 1.0 I think

Habris Mun

@HabrisMun_twitter

anyone here familiar with scala react?

having troubles understanidng modState, setState etc

with one of my react components, it has the capability of creating a new item into the database. It enters the database just fine, but i don't know how to get it to modify the list without refreshing.

AsyncCallback.fromFuture(Api.People.addInsurancePlan(company, planName)).flatMap(a => state.setState(magic goes here).asAsyncCallback).toCallback

and i really don't know what to do because i don't think i understand what's going on underneath the hood. FlatMap lets me access the item from the database, but how do i get it to use that item that is now inserted the database, and insert it into the list for me? saying state.setState(a) doesn't work , says methods are overloaded

state is a StateSnapshot

Roberto Leibman

@rleibman

It's fairly complicated, though the documentation is not bad. I suggest you start with something simpler, start with a button add a non-async callback to start with, then try an asynccallback (you need to map and completeWith, I believe so that you can convert the result to a callback when the async completes). BTW, the project has its own gitter, you may find more detailed help there.

Anthony Cerruti

@srnb_gitlab

@gregfagan declarative? check out outwatch

Antoine Doeraene

@sherpal

@gregfagan you can also check laminar (https://github.com/raquo/Laminar) (not sure about the declarative part, though)

Anthony Cerruti

@srnb_gitlab

Ooh Laminar looks sick

Yilin Wei

@yilinwei

@HabrisMun_twitter Are you still having issues?

Dawid Dworak

@ddworak

@gregfagan you can try https://udash.io as well :)

Rich

@Rich2

How does Scala.js handle Array[Long]s?

Sébastien Doeraene

@sjrd

@Rich2 In a way that they are compatible with the semantics of Array[Long] on the JVM.

Rich

@Rich2

Is the performance reasonable?

Sébastien Doeraene

@sjrd

It depends how you define reasonable. It's not the end of the world, but if you expect it to as fast as the JVM, you're going to be disappointed.

Giuseppe Cannella

@gekomad

how can i passing a js class to scala?
example:

class Car {
    constructor(brand) {
    this.carname = brand;
    }
}
mycar = new Car("Ford");
JSwrapper.f(mycar)

@JSExportTopLevel("JSwrapper")
object JSwrapper {
 @JSExport def f[A](s: A) = ???
}

Sébastien Doeraene

@sjrd

What's wrong with what you've got so far?

Giuseppe Cannella

@gekomad

@sjrd println(s.toString) doesn't print any fields

it prints [[object Object]]

Anthony Cerruti

@srnb_gitlab

Sébastien Doeraene

@sjrd

Well, that is consistent to doing mycar.toString() directly in JavaScript.

Anthony Cerruti

@srnb_gitlab

println and console.log do different things

Sébastien Doeraene

@sjrd

So that is the expected behavior.

Anthony Cerruti

@srnb_gitlab

If you want to call console.log, call js.Dynamic.global.console.log( (although I think global was changed in SJS 1.x so correct me if I'm wrong please)

Giuseppe Cannella

@gekomad

no, println is only an example, actually I need to get the class's fields

Sébastien Doeraene

@sjrd

global was changed in 1.x but that answer still applies

@gekomad Do you mean be able to write s.carname in Scala.js?

For that you'll need to define a facade type for the JS class:

// in Scala.js:
class Car(brand: String) extends js.Object {
  val carname: String = js.native
}

@JSExport def f(s: Car): Unit = println(s.carname)

Giuseppe Cannella

@gekomad

thanks @sjrd I'll look into it

Habris Mun

@HabrisMun_twitter

@yilinwei Yes i apologize for not responding earlier. Power keeps going out here, likely by influence of corona which is affecting productivity -.-

I haven't tried to make progress since i've posted

Nikolay Khoroshevskyi

@rossoha

@sjrd I’va found this repo https://github.com/sjrd/scalatscomp - Could you please give a couple words about it? Seems that it was’t update for some time. Is it still wip ? Also I see that it doens’t compiles and it seems to me that it was genrated programaticaly.. if I’m right, could you give a coule words about that as well. Thanks.

Sébastien Doeraene

@sjrd

@rossoha That was the product of a 24-hour hackaton. We barely had the beginning of a proof of concept. It's completely unusable.

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