scala-js/scala-js

Scala.js, the Scala to JavaScript compiler

TATSUNO Yasuhiro

@exoego

Thanks.

I override with below and it works.

.setings(
  fastOptJS in Compile := Attributed.blank(file("")),
  fullOptJS in Compile := Attributed.blank(file(""))
)

Mustafa Kuscu

@mcku

Also when compiling under dotty, BaseCharsetTest:

ClassType(Ljava_io_Serializable) expected but UndefType found for tree of type org.scalajs.ir.Trees$Undefined

this error when the case is empty

could not reproduce it in a minimal sense

adding expectedChars would get rid of those
See: https://github.com/scala-js/scala-js/pull/3756/files/9e0a1959e5a5d1d4f90b01bb70b7da071831a21c#diff-8e8b9776805c3c46a92816f342baf75dR225

Ntend7777

@Ntend7777

Hello

Sébastien Doeraene

@sjrd

@mcku looks like a dotty bug. It should infer Unit for the type of the match, instead of Serializable.

Mustafa Kuscu

@mcku

they ought to run the scalajs test case to reproduce the bug then, right?

Sébastien Doeraene

@sjrd

Yes.

But it's very possible that it won't reproduce on the JVM, because the JVM backend has a tendency to tolerate and fix things on the fly, whereas the Scala.js backend is more strict in what it accepts.

Eric K Richardson

@ekrich

Which versions of Scala.js emit ES5 or ES6?

For 1.0.0-M8 (Scala.js now emits ECMAScript 2015 code by default) is that ES5?

Sébastien Doeraene

@sjrd

2015 is 6

Eric K Richardson

@ekrich

So does 0.6.x also emit ES6?

Mustafa Kuscu

@mcku

yes, since 0.6.26 scalajs emits ES modules. Many people use ES/ES6 to mean ES2015 and newer.. ES5 is, roughly speaking, old, troublesome JS syntax which has no appeal..

Sébastien Doeraene

@sjrd

@ekrich 0.6.x can emit ES2015 if you ask it to. 1.x can also still emit ES5.1 if you ask it to. In both cases, you can ask them to emit scripts, CommonJS modules pour ES modules.

Eric K Richardson

@ekrich

Wow, ok thanks @sjrd and @mcku. Last time I did any serious web programming was in the IE8 era.

moritz bust

@busti

Can I call a native function that is defined multiple times with a differently typed parameter using a union type variable?

class WebSocket {
  def send(data: String): Unit = js.native
  def send(data: Blob): Unit = js.native
  def send(data: ArrayBuffer): Unit = js.native
}

val myData: String | Blob | ArrayBuffer = ???
websocketInstance.send(myData) // Error

Do I have to pattern match?
Should I wrap my data in case classes for each type to avoid having unions in my application code?

moritz bust

@busti

Also, I cannot seem to pattern match for that union.

[error]  found   : String
[error]  required: String | org.scalajs.dom.Blob | scala.scalajs.js.typedarray.ArrayBuffer
[error]     (which expands to)  String | org.scalajs.dom.raw.Blob | scala.scalajs.js.typedarray.ArrayBuffer
[error]             case d: String      => webSocket.send(d)

TATSUNO Yasuhiro

@exoego

IIUC, test uses fastOptJS-produced JS file by default. How to run test using fullOptJS? I need this to verify that full-optimied JS behave as same as fast-optimizes JS.

TATSUNO Yasuhiro

@exoego

I read this but not mentioned. https://www.scala-js.org/doc/project/testing.html

Sébastien Doeraene

@sjrd

set scalaJSStage in Global := FullOptStage before running test

TATSUNO Yasuhiro

@exoego

@sjrd Thanks !!

aappddeevv

@aappddeevv

@Busti For js functions that take complex arguments, in my definitions, I tend to break out methods with different argument types when the "js union" is too complex especially when js callback signatures are involved. But for unions with simple types, I often leave it as a union argument so you could have send above take a union type. You don't need to have myData be of type union for it to work, it could just be one of the union types. You have to widen the union result then test using js tests, it makes pattern matching much more verbose.

There is an example on stackoverflow.

mushtaq

@mushtaq

I am trying to write a facade for this npm module:
https://github.com/canjs/can-ndjson-stream/blob/master/can-ndjson-stream.js

as below:

@JSImport("can-ndjson-stream", JSImport.Namespace)
@js.native
object CanNdJsonStream extends js.Object {
  def ndjsonStream(response: ReadableStream[Uint8Array]): ReadableStream[js.Object] = js.native
}

But I get the following error:

scala.scalajs.js.JavaScriptException: TypeError: $i_can$002dndjson$002dstream.ndjsonStream is not a function

What am I missing?

Sébastien Doeraene

@sjrd

The function is exported as a default member, not under its name.

moritz bust

@busti

@aappddeevv Do you happen to have a link to that example? I cannot find it.

mushtaq

@mushtaq

thanks @sjrd I changed JSImport.Namespace to JSImport.Default, now the error is:

scala.scalajs.js.JavaScriptException: TypeError: $moduleDefault(...).ndjsonStream is not a function

Not sure I interpreted your suggestion correctly.

ok, this seems to work:

@JSImport("can-ndjson-stream", JSImport.Namespace)
@js.native
class CanNdJsonStream extends ReadableStream[Uint8Array] {
  def this(response: ReadableStream[Uint8Array]) = this()
}

mushtaq

@mushtaq

sorry, it should be extends ReadableStream[js.Object]

aappddeevv

@aappddeevv

@Busti here

Li Haoyi

@lihaoyi-databricks

Anyone know what's the current status of new java.text.DecimalFormat(template).format in Scala.js?

It seems it isn't supported in javalib, but not sure if there's a similar API I can use that does the same thing, or some third-party shim

presumably some amount of formatting ability must be present to make Float#toString work

Li Haoyi

@lihaoyi-databricks

https://github.com/cquiroz/scala-java-locales seems to support it but the library doesn't seem to be published to maven central

at least not for scala 2.13

Li Haoyi

@lihaoyi-databricks

and the version for 2.12 blows up with a NPE on https://github.com/cquiroz/scala-java-locales/blob/v0.5.5-cldr31/core/src/main/scala/java/util/Currency.scala#L36

Li Haoyi

@lihaoyi-databricks

CC @cquiroz

Li Haoyi

@lihaoyi-databricks

Seems like it doesn't like the java.util.Locale.ENGLISH locale

Li Haoyi

@lihaoyi-databricks

new java.text.DecimalFormat("0.000000E00").format(910) seems to return different values on scalajs/scalajvm

Li Haoyi

@lihaoyi-databricks

I wonder if there's a cheaper way if getting a EN/UK/US-only DecimalFormat if I don't care about other locales? Otherwise scala-java-locales adds almost a megabyte of compiled JS code

LeeTibbert

@LeeTibbert

Recently I have been porting, with thanks & appreciation, from scala-js to scalanative. I have come across two scala-js 'features' that I
changed for the SN port. Before I invest effort in creating PRs for scala-js, I thought I would describe the 'feature' and ask if it is a
candidate for a PR or if it is intended. Thank you for guidance.

The first feature is in java.util.AbstractCollection.scala. j.u.ArrayDeque.scala and, I believe, j.u.AbstractList.scala inherit toString from

LeeTibbert

@LeeTibbert

AbstractCollection. Scala JVM, and now Scala Native, format a Deque containing the elements a, b, and c as [a, b, c]. Scala-js

formats this as [a,b,c]. Note the lack of whitespace after the commas.

There is a strong requirement in SN to match JVM output where feasible. Scala-js may be trying to match some forms of CSV lists.

The fix is trivial. One character of code and probably a unit-test case. Please advise.

LeeTibbert

@LeeTibbert

The second feature is that HashMap.scala appears to be missing the getOrDefault method. Other missing methods may be identified
as I create a SN PR.

I offer these PRs in the spirit of feeding the ancestors, not of being critical of the hand that feeds me...

The HashMap.getOrDefault implementation is again trivial but will need to be reviewed for performance impact in scala-js.

I am told that a lot of work has been done in scala-js in that area and would hate to introduce a regression.

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