Hi, I try to create a wrapper around expressjs (wi...

# javascript

[mmaillot]

Hi, I try to create a wrapper around expressjs (with enhancements). I have this code :

@JsModule("express")
external class Express {
    fun get(route: String, callback: (req: Request, res: Response) -> Unit)
    fun listen(port: Int, callback: Callback?)
}

And I create a class ExpressKt to overload express :

class ExpressKt(private val express: Express = Express()) {
    fun listen(port: Int, callback: Callback) {
        express.listen(port, callback)
    }
}

And finally the code to run :

fun main(args: Array<String>) {
    //val app = Express()
    val app = ExpressKt()
    app.listen(3000, {
        println("Listening on port 3000")
    })
}

But when i compile code, the index import the wrong library (module.exports, require('kotlin'), require('lib'))

[mmaillot]

If I use directly Express in place of ExpressKt, it's good, I have : module.exports, require('kotlin'), require('express'))

[mmaillot]

Do you know why ?

[mmaillot]

Express and ExpressKt are in another gradle module

[mmaillot]

Ok, ifI move all the code in the same module, it works. It comes from gradle module split...

[anton.bannykh]

So did the compiler generate require('express') in the lib.js originally?

[mmaillot]

Ok, I should set output also in the lib ? You can see the project here : https://github.com/m-maillot/expresskt

[mmaillot]

I don't have any lib.js

[mmaillot]

Yes, I have a lib.js in lib/build/classes/kotlin/mail/lib with express

[anton.bannykh]

If it has require('express') then it works as intended

[anton.bannykh]

The logic being that you don't need to require a library if you don't use any declarations

[anton.bannykh]

If you use it in a seprate module, that module itself should require the library.

[anton.bannykh]

Does that make some sense?

[mmaillot]

Not really, I have a subproject gradle to be able to reuse this code. And I want to link my gralde module to this submodule to use this code. KotlinJS can't merge these two modules in one file ?

[anton.bannykh]

Do you just want to be able to run your code in, say, Node? Or do you want to create a self-contained js file? How familiar are you with JS tools (e.g. npm, webpack, etc)?

[anton.bannykh]

(there is a number of solutions, not sure which to suggest)

[anton.bannykh]

Unless you are a seasoned JS developer, I would suggest starting with https://github.com/Kotlin/kotlin-frontend-plugin

[anton.bannykh]

It 'just works' for a lot of cases.

[mmaillot]

I'm a java dev, not a JS dev. I want to use kotlin to dev backend for firebase. I'll look for JS tools to accomplish what I want. Thank for your help !

[anton.bannykh]

@mmaillot In that case take a look at the kotlin-frontend-plugin I've mentioned. 😃 It sets things up for you so that you can run and test your code, pack it into a bundle, etc. I imagine it should work well for your case.

[anton.bannykh]

And the configuration files it generates (inside the build directory) is also a reasonable starting point to get familiar with webpack, npm, karma, etc.

[anton.bannykh]

Good luck!

[mmaillot]

Finally, I use the yarn link and change config to make it works, almost... 😄 Generated index.js code require('index') in place of require('expresskt')... I don't know why if you have an idea ? https://github.com/m-maillot/expresskt/blob/master/demo/output/index.js#L36

[anton.bannykh]

Probably due to this line: https://github.com/m-maillot/expresskt/blob/master/lib/build.gradle#L38

[mmaillot]

Yes, thank you, it works now 🙂
Is it a good practices to publish lib on npmjs and maven repo and to use it in other project to add dependency into package.json and build.gradle ?

[anton.bannykh]

Well, that's what we do. If you do that, don't forget to publish .meta.js at the minimum, and optionally js.map, and *.kjsm files for best experience.

[mmaillot]

Yes, thank you !