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is there something wrong with the following test (on kotlin/js)?

@Test fun `on zero throws`() {
    assertFailsWith<ArithmeticException> {
      1 / 0
    }
  }

it fails with the following message “AssertionError: Expected an exception of class ArithmeticException to be thrown, but was completed successfully.”

Hello there, Currently service.kt [Snippet 1]

@file:JsExports

external interface ServiceConfiguration {
  var appId: String
  var debug: Boolean?
}

fun service(config: ServiceConfiguration)

Yields the following typescript declaration (code out of this context is redacted): [Snippet 2]

type Nullable<T> = T | undefined | null

export interface ServiceConfiguration {
  appId: string;
  debug: Nullable<boolean> // want this to be optionally provided
}

export function service(config: ServiceConfiguration);

After importing this bundled library in typescript, calling [Snippet 3]

const service = service({ appId: "<app-id>" }) // troubles the ts compiler

The compiler expects both arguments like so [Snippet 4]

const service1 = service({ appId: "<app-id>", debug: undefined }) // ts compiler is happy
const service2 = service({ appId: "<app-id>", debug: true }) // ts compiler still happy

Question is, how do I make the kotlin compiler to generate [Snippet 5]

export interface ServiceConfiguration {
  appId: string;
  debug?: boolean // want this to be optionally provided
}

instead of the one being generated on [Snippet 2]. So that I may use it as written in [Snippet 3]?

Hey guys, with react, how do you decide whether you'd use RComponent, FC function or the RBuilder extension? In regular react I only used functions and arrow functions but then I could return HTML code and put my useStates and logic before that. What's the state of kotlin, I am kinda confused where to put logic and whether to use the classes or the functions. So with these 3 approaches is it up to preference or are there benefits to each one?

Hi folks, how does one filter javascript test in a KMP project with gradle?

./gradlew jsTest --tests integration.*

Throws with

Unknown command-line option '--tests'.

./gradlew jsBrowserTest --tests integration.*

runs all the tests (does not filter)

./gradlew jsNodeTest --tests integration.*

runs all the tests (does not filter)

Hey guys, Any update on a compatible mocking library for Kotlin/JS? Already tried Mockk, but seems that's not supported yet.

Any idea why I start getting this when I remove

-Xir-property-lazy-initialization

? I thought the lazy init is exeprimental, and stuff might broke with it, not without it. 🤡

Hey, does anybody have a robust heuristic they use when wrapping a javascript library? I've wrapped several quite easily, but there are edge cases with others that I don't really understand. For example, https://pouchdb.com/?ref=w3use (npm: pouchdb-browser) looks quite straightforward from the docs, but it doesn't seem to let me apply @JsModule to a package (with a PouchDB object or class), object, class, function, or function property (I get the usual "not a constructor", "not a function", etc). (Right now for this one I made a

dynamic

using require (

val DB = require("pouchdb-browser").default; val db = DB("my_new_db")

) and am just delegating to that in a wrapper class, which is fine.) Just an example, but maybe useful to help illustrate the process one can step through to make the JsModule approach work.

When trying to run my web app i get "Something went wrong when displaying this page, Error SIGTRAP". Running

./gradlew run

gives no errors, and the devtools are disconnected. How do I go about debugging this? I have no feedback and absolutely no idea what is causing this, gradle is giving me thumbs up and successful tasks for build and run.

:web-app:browserDevelopmentRun > webpack 5.35.0 compiled successfully in 9236 ms

Hey guys, any idea how to test coroutines in KotlinJs? Most solutions I've come across workarounds that should potentially work with Kotlin Multiplatform, but not Kotlin/JS on it's own. Tried using the workaround suggested here: https://youtrack.jetbrains.com/issue/KT-22228. However, the

promise

keyword doesn't exist in Kotlin/JS alone.

Hello everyone, is this a dead project or we expect some updates soon? https://github.com/Kotlin/kotlinx-nodejs

I get this error when I recompile my Kotlin/JS project in Idea while running it using `jsBrowserDevelopmentRun`:

Uncaught Error: Module build failed (from ../../node_modules/source-map-loader/dist/cjs.js):
Error: ENOENT: no such file or directory, open '...idea-project-folder\build\js\node_modules\webpack-dev-server\client\index.js'

I use Kotlin 1.5.30 with Compose/Web 1.0.0-alpha4-build348. The

build\js\node_modules\webpack-dev-server

folder really does not exist. I have already tried setting

versions.webpackDevServer.version = "4.0.0"

(I found this hint somewhere), and setting

config.watchOptions

but nothing seems to help 😞 Do you have any idea? Thanks.

Does the equivalent of https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/toString exist? I.e. can I get at the source after it has been compiled to js?

How do you pass children props to a class component in Kotlin React? Currently, I'm doing:

child(MyClassComponent::class) {
  child(SomeFunctionalComponent)
}

then, in MyClassComponent.render:

if (...) {
  props.children()
}

This works fine with

run

, but fails with `browserProductionWebpack`:

TypeError: _.render is not a function

Follow up question regarding JsExports. Asking to see if someone already asked so that I may not open a duplicate ticket currently exporting

val lambdaFunction: (user: User)->Unit

yields the following typescript definitions

readonly lambdaFunction: (p0: User)-> void

Which hurts readability. I would expect it to be exported to

readonly lambdaFunction: (user: User)-> void

Is there already a ticket for this?

Hello there! I am trying to switch the Javascript part of multi-platfatform library to IR. But now things do not compile anymore and I get the error below. Does anyone know what is going on there? Things work fine with the Legacy compiler.

> Task :commonmp:compileKotlinJs FAILED
e: org.jetbrains.kotlin.util.KotlinFrontEndException: Front-end Internal error: Failed to analyze declaration TypedAttributes
File being compiled: (3,1) in .../TypedAttributes.kt
The root cause java.lang.AssertionError was thrown at: org.jetbrains.kotlin.builtins.KotlinBuiltIns$3.invoke(KotlinBuiltIns.java:93)
        at org.jetbrains.kotlin.resolve.ExceptionWrappingKtVisitorVoid.visitDeclaration(ExceptionWrappingKtVisitorVoid.kt:43)
        at org.jetbrains.kotlin.psi.KtVisitorVoid.visitDeclaration(KtVisitorVoid.java:453)
        at org.jetbrains.kotlin.psi.KtVisitorVoid.visitDeclaration(KtVisitorVoid.java:21)
        at org.jetbrains.kotlin.psi.KtVisitor.visitNamedDeclaration(KtVisitor.java:398)
        ...
Caused by: java.lang.AssertionError: Built-in class kotlin.Any is not found
        at org.jetbrains.kotlin.builtins.KotlinBuiltIns$3.invoke(KotlinBuiltIns.java:93)
        at org.jetbrains.kotlin.builtins.KotlinBuiltIns$3.invoke(KotlinBuiltIns.java:88)
        at org.jetbrains.kotlin.storage.LockBasedStorageManager$MapBasedMemoizedFunction.invoke(LockBasedStorageManager.java:578)
        at org.jetbrains.kotlin.storage.LockBasedStorageManager$MapBasedMemoizedFunctionToNotNull.invoke(LockBasedStorageManager.java:651)
        at org.jetbrains.kotlin.builtins.KotlinBuiltIns.getBuiltInClassByName(KotlinBuiltIns.java:223)
        at org.jetbrains.kotlin.builtins.KotlinBuiltIns.getAny(KotlinBuiltIns.java:228)
        ...

I have a kotlin/js project that generates code based on skeleton files by doing only simple replacements (replace "[-name-]" with name coming from user input for example). I end up processing .h, .cpp, readme, etc... (live here https://jamba.dev/quickstart/web/) Of course now I want to make it more sophisticated and have if/loop in my "replacement" so clearly a search/replace strategy won't work... any idea of a lightweight project that would work with kotlin js?

I am trying to use squirrelly in my program but was unable to import it as Kotlin, so reverting to use dynamic:

val templateEngine: dynamic = js("Sqrl")
 templateEngine.render(content, tokens)

The issue is that

tokens

is a

Map<String, String>

and Sqrl is not happy with it... I used this code to workaround the issue:

val data: dynamic = js("{}")
tokens.forEach { e -> val k = e.key; val v = e.value; js("data[k] = v") }
templateEngine.render(content, data)

which works... But this seems so hacky. Is there a better way?

Is it possible How to change the nodejs version that is used to run webpack? It uses 14/LTS even when changing the system default to 16

Hey guys, I’m compiling a lib that is supposed to be consumed by TypeScript. How do I export a

Long

to JS with the IR compiler ???

@JsExport
fun long(): Long = 0x12_34_56_78_9A_BC_DE_F0

Calling this

long

function with typescript returns the following object:

Long { _low: -1698898192, _high: 305419896 }

Casting to int does NOT do the trick as the compiler overflows :

@JsExport
fun int(): Int = 0x12_34_56_78_9A_BC_DE_F0.toInt()

Calling this

int

function with typescript returns a negative number:

-1698898192

How can I export a

Long

?

Hello! I’m trying to reduce the size of a multiplatform library that I want to use on a web project, and even after enabling the IR compiler and divided into sub-modules it’s still too big to be used on a browser (~3MB). While doing some tests, with a clean project (with only the greeting function), I’ve noticed: • library is smaller with kotlin 1.5.10 • adding ktor (without making any call), automatically adds the kotlinx.atomicfu to the .js output Is there any possibility to manually exclude it? I’m also listening for solutions on how I can reduce it’s size 🙂

Is there some article about best practices for Kotlin/JS development? Something like use simple arrays when possible, use external interfaces instead of data classes, etc.?

Hey friends! I'm migrating to the JS IR compiler and had a question: We previously had some "js interface tests" in our

jsTest

sourceset which would basically do something ugly like:

js("""
  var assert = require('assert');
  var moduleUnderTest = require('myGroup-myModule');
  assert(moduleUnderTest.method("parameter") == expectedResponse);
""")

While a little janky, this kind of test let us verify that things like JsName were added where expected and that we didn't accidentally break the public API for our JS consumers. Now, under JS IR, the

require

for my module is failing, because there's no JS file in the expected path. There is a package.json though. Does anyone know how to get the module import working again under IR? I'd also be happy to replace this with a JS file (instead of using

js()

) that actually uses the final JS artifacts if anyone has an example of a project that does that! EDIT: it looks like I can remove the

require(…)

and get some stuff working, but not everything...

After bumping to the JS IR Compiler (and Kotlin 1.5.31) I'm running into a compiler error that I can't seem to track down when compiling a specific test compilation. All of my main compilations, and all of my other test compilations seem to compile and run just fine. Does this look like a known issue to anyone? Does anyone know if there's a logfile lingering somewhere that might give me some more details? Truncated stacktrace below -- full stacktrace in thread.

> Task :my-module:compileTestDevelopmentExecutableKotlinJs FAILED
e: java.lang.NullPointerException
	at org.jetbrains.kotlin.ir.backend.js.transformers.irToJs.IrElementToJsStatementTransformer.visitCall(IrElementToJsStatementTransformer.kt:132)
	at org.jetbrains.kotlin.ir.backend.js.transformers.irToJs.IrElementToJsStatementTransformer.visitCall(IrElementToJsStatementTransformer.kt:20)

* What went wrong:
Execution failed for task ':my-module:compileTestDevelopmentExecutableKotlinJs'.
> A failure occurred while executing org.jetbrains.kotlin.compilerRunner.GradleCompilerRunnerWithWorkers$GradleKotlinCompilerWorkAction
   > Internal compiler error. See log for more details

I have a plenty of DTO `data class`es from our backend team (so Ican't change them). I need to serialize some of them to GraphQL, so I'm writing custom serializers:

val MessageTemplateTextDtoCreateInput.gql
    get() = buildString {
        append('{')
        appendKV("body", body)
        appendKV("languageId", languageId)
        appendKV("subject", subject, true)
        append('}')
    }

fun StringBuilder.appendKV(key: CharSequence, value: Any?, last: Boolean = false) {
    append(key)
    append(':')
    if (value is String) {
        append('"')
    }
    append(
        when (value) {
            is Array<*> -> value.joinToString(",", "[", "]") {
                it.asDynamic().gql as? CharSequence ?: "" // !!! PROBLEM HERE !!!
            }
            else -> value
        }
    )
    if (value is String) {
        append('"')
    }
    if (!last) {
        append(',')
    }
}

The problem is, how can I dynamicaly get the

.gql

extension value I created? • I understand, that Kotlin can't know from

Array<*>

that the members has the

.gql

extension. • I know I can't use rflection in JS to look if the extension is there. • Sealed classes/interfaces might be the solutionm, but I can't change the DTOs. •

asDynamic().gql

does not work (this is a bit WTF to me, I thought this might work and at worst throw an exception or something.) So, any idea how to do this?

Hello How can I configure Kotlin/JS so that in

webpack.config.js

I will be able to set custom file name (instead of webApp.js)

Normally this channel is full of questions, issues, bug reports. I just want to give kudos to the Kotlin team that makes using K Kotlin for js possible. Great job folks, keep up the great work! 💪 Thanks to you, I actually like web development. I can't wait for K/JS to be a real, prod-ready alternative for TS. It already makes a difference for some projects and I heard this surprise "wow, so Kotlin works for JS?" multiple times. Let's bring proper type-safety to the web dev world 😄

I'm using npm-publish plugin (by Martynas Petuška) and after I upgraded to Kotlin 1.5.30 the

packages.json

generated has neither

dependencies

nor

bundledDependencies

entries. Do we need to explicitly set those from now on?

Hi everyone ! So I was trying to push a little project to github pages, everything works fine locally but when I try to deploy it, it fails on the

testing

part saying this :

> Failed to execute all tests:
  :browserTest: java.lang.IllegalStateException: Errors occurred during launch of browser for testing.
  - Opera
  - Firefox
  - Chromium
  Please make sure that you have installed browsers.
  Or change it via
  browser {
      testTask {
          useKarma {
              useFirefox()
              useChrome()
              useSafari()
          }
      }
  }

I know that the issue is related to the fact that it can't find firefox / chromium / opera... But how can I make it so tests are run correctly when deploying without having to remove the whole UI related part in my tests ?

Hello all! If I want to extend a external class with some es6+ apis, what is the proper way to do that? I tried to do an extension function (although I know that doesn't really makes sense) like

external fun Blob.stream(): Promise<ReadableStream>

But the compiler told me that's illegal. Intellij suggested I change it to

@Suppress("NOTHING_TO_INLINE")
inline fun Blob.stream(): Promise<ReadableStream> = asDynamic().stream() as Promise<ReadableStream>

which I think will work for me, but I was wondering if anyone knows of a better way to do this?