HI! How to provide an independent TS/JS project's function implementation to Kotlin? I do not unders...

# javascript

[Марк Вавилов]

HI! How to provide an independent TS/JS project's function implementation to Kotlin? I do not understand how to do it with gradle or whatever else. Relatable stack overflow question


Situation:
I have a Kotlin project and I want to use a TypeScript function from an opensource app, so I copied the source code to my project. The app starts via yarn.

[Big Chungus]

First you need to declare an npm dependency in gradle

kotlin.sourceSets.named("jsMain") {
  dependencies {
    implementation(npm("package-name", "version"))
  }
}

Then you can either use ./gradlew generateExternals and pray that dukat works or write external declarations yourself.

[Big Chungus]

package-name and version appears the same as it would in package.json, so all the protocols like "file:xxx" are supported as well.

[Big Chungus]

You can also hack it with local TS sources, however I do not recommend it. If you still must stick with it, create a small npm module somewhere on your repo and use that via file:path/to/that/module version instead. I recommend generating absolute path to that module in gradle instead of trying to work out relative path from package.json that kotlin plugin generates

kotlin.sourceSets.named("jsMain") {
  dependencies {
    val pathToLocalNpmModule = rootProject.projectDir.resolve("js/my-module").canonicalPath
    implementation(npm("my-module", "file:$pathToLocalNpmModule"))
  }
}

[Big Chungus]

Posted all that on SO as well for persistence.

[Марк Вавилов]

@Big Chungus Thank you for the response! if I want to include the whole project, I should use package-name="file:relative_path_to_project"?

when i do so, build tells me 
Package "file:relative_path_to_project" refers to a non-existing file '"root_project/build/js/project@0.1.0"'. What is wrong?

[Big Chungus]

Note my comment about generating absolute path in gradle

[Big Chungus]

Also know that kotlin (nor any other js runtime except deno) cannot work with ts files, those need to be transpiled to js

[Big Chungus]

(drop a +1 on SO if it ends up helping you to solve your issue)

[Марк Вавилов]

@Big Chungus I declared an npm dependency like in your first comment and generated declarations via dukat. But when I call the function, it does not find it at runtime: onStart ERROR my_func is not defined. Do you have any idea what could go wrong?

[Big Chungus]

Dukat went wrong. It's still very experimental. I usually just write external declarations of the stuff I need myself. I might use dukat generations as a starting point sometimes.

[Big Chungus]

Plus it seems that dukat is unable to link stuff that have their declarations published separatelly (@types/xxx)

[Марк Вавилов]

Can you please suggest any guide on writing declarations?

[Big Chungus]

I've dropped some examples in SO. There's no definitive guide, because JS world is messed up and there are million ways of importing/exporting stuff...

[Edoardo Luppi]

Stumbled upon the SO answer two years later. Thanks!