I'm confused, the result in build/distributions is a somewhat correctly looking webpackd file. Howev...

# javascript

[JoakimForslund]

I'm confused, the result in build/distributions is a somewhat correctly looking webpackd file. However, there is no exports open what so ever and the result from importing it into a javascript project and logging the object is:

module {__esModule: true, Symbol(Symbol.toStringTag): "Module"}

The code that is supposted to be exported is from multiplatform common, but I also tried to export directly from the javascript target. What am I missing?

[Ilya Goncharov [JB]]

Hello, could you please specify, what do you want to import? Webpack is commonly used for browser needs, it bundle all modules in one javascript file, that browser can execute
If you want to import your Kotlin/JS module from external JavaScript application, you can configure Webpack to bundle in “library” mode (https://webpack.js.org/configuration/output/#outputlibrary) or you can use “nodejs” target
If you want to reuse your Kotlin/JS modules from another Kotlin/JS projects, you can publish Kotlin/JS module to Maven repository for example

[JoakimForslund]

As far as I gathered there was a lot of things needed to be done in order to make the output from js-dce and the javascript output to become exportable as a library.

First and foremost it does not seem to support esModule system yet. So whatever code gets built needs to make sure it adds export default to the top of the file.

Something like this:

contents = contents.replace("(function (_, Kotlin) {", "export default (function (_, Kotlin) {")
        contents = contents.replace("}(module.exports, require('kotlin')));", "}({}, require('kotlin')));")

and then you need to make sure as you said, that webpack uses the library mode. Which for whatever reason works the best when using commonjs2 as a target

[JoakimForslund]

There is also the issue with missing babel dependencies on the produced output, especially if the output file contains data classes, enums and linkage between them, because of typeof

[JoakimForslund]

I created a gradle task which creates this webpack config.
It then uses the output from jc-dce and tries to glue this together into an exportable npm package.

Untitled

[Ilya Goncharov [JB]]

ESModules are not supported yet, but webpack supports commonjs, amd and umd module sustems as well, as I know
You can find pure compiler output in
build/js/packages/<package-name>/kotlin folder

[JoakimForslund]

Yeah I tried that, but it has all the same problems as the js-dce does. Oh and also, yes the code/library is supposed to be used in a browser project

[JoakimForslund]

And I wanted the library to become as small as possible

[Ilya Goncharov [JB]]

Why do you want to declare all Kotlin/JS dependencies as entry of webpack?
You can easily add configuration to your webpack config via webpack.config.d folder in your project root
In this folder you can create js file with configuration of webpack config object, that you can call with config
For example
webpack.config.d/additional.js

config.output = config.output || {};
config.output.library = 'lib-commin'
config.output.libraryTarget = 'comminjs2'
config.output.libraryExport = 'default'

[JoakimForslund]

Oh yeah, so along with the custom webpack file, I also create a custom package.json, which has devDependencies needed.

The reason is because for whatever reason "@babel/runtime": "^7.6.0",

Is needed, I'm not sure if this is because of the project using the library or not, but I figure it should be the same

[JoakimForslund]

At any case. if i run: npm ../build/js/packages/<package-name>/

And try to import that, I get issues with babel and typeof

[JoakimForslund]

(My webproject is in another folder in the same root as the multiplatform project)

[JoakimForslund]

I'll try to do what you are suggesting, and give back with the specific "log problem"

[JoakimForslund]

(I'll also remove the dependency on kotlinx-serialization-kotlinx-serialization-runtime, since there is no npm dependency in existance for that right now) In the test of using the above folder as install source

[Ilya Goncharov [JB]]

Do you declare npm dependencies in build.gradle file?

[JoakimForslund]

No, only the dependencies { implementation..} in the javascript target

[Ilya Goncharov [JB]]

You can do it, it can support to work with npm
You can find it in release notes of 1.3.40 (first version with this feature)
https://blog.jetbrains.com/kotlin/2019/06/kotlin-1-3-40-released/
Part Experimental support for NPM and Webpack

[JoakimForslund]

Yeah but what should I add? There is no public npm package for kotlin-serialization

[JoakimForslund]

Afaik

[JoakimForslund]

So the error that pops up trying to run npm ../build/js/packages/<package-name>/

and then later in the webapp code using the exported library (which is transpiled with babel)
i run import * as libObj from 'lib-common';

When trying to print the libObj object to console
I get Cannot read property 'MyPackageName' of undefined

Which then points me towards this section:

var package$MyPackageName = _.MyPackageName || (_.MyPackageName = {});
  package$MyPackageName.CoreRepository = CoreRepository;
  package$MyPackageName.Device = Device;
  package$MyPackageName.Game = Game;

[JoakimForslund]

And that is because (function (_, Kotlin, $module$kotlinx_coroutines_core) {

never sends in the module.exports

[JoakimForslund]

so _ is in this case undefined

[Ilya Goncharov [JB]]

Do you use DCE?

[Ilya Goncharov [JB]]

If possible, it will be great, if you share your project, it will reveal many of additional questions

[JoakimForslund]

I have it in the project, but is the output in /build/js/packages/<package-name>/ not pure?

[JoakimForslund]

I can go ahead and publish a trimmed down repo of it all

[Ilya Goncharov [JB]]

Basically, webpack integrated to work with this folder
And in this folder there is pure output of compiler
DCE’s output will be in another folder

[JoakimForslund]

So it should not have affected this specific test

[JoakimForslund]

In essence, it feels like the kotlin javascript output format is not behaving well to export a library or a default

[JoakimForslund]

The same result happens no matter what moduleKind
i define in:

kotlinOptions {
        moduleKind = "commonjs"
        metaInfo = true
        sourceMap = false
        sourceMapEmbedSources = null
        //outputFile = jsOutputFile
    }

[JoakimForslund]

@Ilya Goncharov [JB] https://github.com/Syrou/KotlinMultiplatformWithJavascriptNotLibraryFriendly

So basicly build the :common module

Write npm install ../build/js/packages/companyxr-common while inside the webapp-folder

and then try npm run start

This will give you an error with @babel and that it needs runtime, once you get passed that
you will run into the error i posted above

[JoakimForslund]

(Given that you uncomment the rows in index.js)

[Ilya Goncharov [JB]]

Ok, I see problem
Now we have no implemented story with JavaScript application, consuming Kotlin/JS module (it is in plan)
The problem is how node (and webpack) resolve required modules
It tries to find in local node_modules, then tries to find in parent’s node_modules etc
When you run webpack in your webapp folder, you have babel installed only in ./webapp node_modules, but Kotlin/JS module is parallel hierarchy level in ./build/js
When webpack build bundle, it finds babel’s dependencies for Kotlin/JS module in build/js/node_modules instead of webapp/node_modules, where babel is installed

[JoakimForslund]

Yes, that is why i went ahead and created a gradle task
as you can see in the build.gradle.kts which creates a custom package.json and webpack.config.js in order to solve that problem

[JoakimForslund]

But it still does not solve the issue where the exported kotlin javascript code does not seem to be mix nicly with how a default exports default or module.exports should behave

[JoakimForslund]

So that is in planning phase?

[Ilya Goncharov [JB]]

You have several options:
1. You can define resolve.modules for your webpack in webapp
https://webpack.js.org/configuration/resolve/#resolvemodules
You should define it in absolute style to point to node_modules of your webapp or in relative style based on build/js/packages/<package-name>/kotlin
For example:

resolve.modules = ['node_modules', '../../../../../webapp/node_modules]

2. You can change your layout
You need to declare your own package.json in root of project
In this case, npm install modules in root node_modules and node should find babel

[JoakimForslund]

So adding resolve.modules = ['node_modules', '../../../../../webapp/node_modules] inside the folder webpack.config.d as a new file?

[Ilya Goncharov [JB]]

No, you should patch your webpack.config.js in webapp
I added to it:

resolve: {
    modules: ['node_modules', '../../../../../webapp/node_modules']
}

[Ilya Goncharov [JB]]

It heals babel’s error during webpack start

[Ilya Goncharov [JB]]

But when I open webpack-dev-server page on the browser, I get error
Uncaught TypeError: Cannot read property 'company' of undefined

Without babel-loader, your sample works well
It can be babel-related problem

[JoakimForslund]

Yeah thats the issue, because module.exports never get bound to the exported kotlin code

[JoakimForslund]

Thats why I did

contents = contents.replace("(function (_, Kotlin) {", "export default (function (_, Kotlin) {")
        contents = contents.replace("}(module.exports, require('kotlin')));", "}({}, require('kotlin')));")

in the custom task that I created (Which is currently commented out)

[JoakimForslund]

Which makes sure the is a export default

[JoakimForslund]

Because the reason we get that error is because _ is indeed undefined

[JoakimForslund]

And that works as well

[Ilya Goncharov [JB]]

It is a bit strange for me, that it works without babel, and doesn’t works with babel
Seems that it doesn’t works properly in this case and loose module.exports value

[JoakimForslund]

So if you add "@babel/plugin-transform-modules-commonjs": "^7.6.0", to devDependencies in the webapp

[JoakimForslund]

and then add it to the babel plugins in webpack

[JoakimForslund]

That solves that issue right?

[JoakimForslund]

plugins: [
                '@babel/plugin-transform-regenerator',
                '@babel/plugin-transform-runtime',
                '@babel/plugin-syntax-dynamic-import',
                '@babel/plugin-transform-modules-commonjs'
              ],

[Ilya Goncharov [JB]]

Sorry, unfortunately I don’t know, what babel’s presets can solve this issue

[JoakimForslund]

Oh it does solve it, just wanted you to verify on your end. But now the issue with kotlin serialization remain. where I can't add it the the common project without the webapp compile getting problems again

[JoakimForslund]

since there is no npm repo for it

[Ilya Goncharov [JB]]

Why can’t you declare it in as usual maven dependency in build.gradle.kts?

[JoakimForslund]

Because it get exported to build/js/packages/companyxr-common/package.json as a dependency that does not exist

[JoakimForslund]

Resulting in: npm ERR! 404 Not Found - GET <https://registry.npmjs.org/kotlinx-serialization-kotlinx-serialization-runtime> - Not found

[Ilya Goncharov [JB]]

The option is not to declare companyxr-common as dependencies in package.json, but as alias for webpack

[JoakimForslund]

How do you mean?

[JoakimForslund]

If I understand you correctly, this is what I tried with the js-dce solution I came up with:

entry: {
        "kotlin":"./src/kotlin.js",
        "glootxr-common" :'./src/glootxr-common.js',
        "kotlinx-serialization-kotlinx-serialization-runtime": "./src/kotlinx-serialization-kotlinx-serialization-runtime.js",
        "kotlinx-coroutines-core":"./src/kotlinx-coroutines-core.js"

    },
    resolve: {
        alias: {
            "kotlin": path.resolve(__dirname, './src/kotlin.js'),
            "kotlinx-serialization-kotlinx-serialization-runtime": path.resolve(__dirname, './src/kotlinx-serialization-kotlinx-serialization-runtime.js'),
            "kotlinx-coroutines-core": path.resolve(__dirname, './src/kotlinx-coroutines-core.js')
        },
        extensions: [".js"]
    },

inside of webpack

[JoakimForslund]

(I have no clue what I'm doing, but it seems to be doing something)

[Ilya Goncharov [JB]]

You can add to resolve section of your webpack.config.js

alias: {
     "companyxr-common": path.resolve(__dirname, "../build/js/packages/companyxr-common")
}

And not install companyxr-common via npm

[JoakimForslund]

That is probably the best way to be honest.
Question though, How would you do it then if this was all being done through DceJs?

[JoakimForslund]

So everything is minified

[JoakimForslund]

I know team members on web will be frustrated if i don't present a solution that is a bit slimmer

[Ilya Goncharov [JB]]

I find that you override DCE task, if js files are appeared in “shared” folder, you can configure alias for webpack on this folder instead of “build/js/...”

[JoakimForslund]

I'll try that, thanks so much for all your help! 🙂