Error: Cannot find module 'abort-controller' - REST call with JS

[FabianRohr]

Ktor Version and Engine Used (client or server and name)
ktor 1.3.0

Describe the bug
When performing a simple get request via the compiled JS code in a Kotlin multiplatform project using ktor, the following error is thrown:

(node:46932) UnhandledPromiseRejectionWarning: Error: Cannot find module 'abort-controller'
Require stack:
- /example-js/node_modules/ktor-ktor-client-core.js
- /example-js/node_modules/ktor-ktor-client-auth.js
- /example-js/node_modules/common.js
- /testRest.js
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:794:15)
    at Function.Module._load (internal/modules/cjs/loader.js:687:27)
    at Module.require (internal/modules/cjs/loader.js:849:19)
    at require (internal/modules/cjs/helpers.js:74:18)
    at AbortController_0 (/example-js/node_modules/ktor-ktor-client-core.js:15169:24)
    at /example-js/node_modules/ktor-ktor-client-core.js:15106:20
    at /example-js/node_modules/ktor-ktor-client-core.js:15081:3
    at Coroutine$commonFetch.doResume (/example-js/node_modules/ktor-ktor-client-core.js:15136:116)
    at commonFetch (/example-js/node_modules/ktor-ktor-client-core.js:15164:23)
    at Coroutine$execute_dkgphz$.doResume (/example-js/node_modules/ktor-ktor-client-core.js:14513:25)

To Reproduce
Setup a Kotlin multiplatform project so that when you build via gradle, Kotlin generates the node_modules folder with your JS code including kotlin.js and common.js via the assembleJs gradle task. Then try to perform a simple get request using the ktor client like so:

test.kt in common/src/jsMain/kotlin/com.myApp/test.kt:

suspend fun getGoogle(): String {
    val client = HttpClient()
    return client.get<String>("https://www.google.de")
}

fun returnPromise(): Promise<String> = //or Promise<Unit> for voids
        GlobalScope.promise {
            getGoogle() // return a String
        }

testRest.js in example-js/:

const common = require("./node_modules/common")
console.log(common.returnPromise())

Also, when I add the actual abort-controller manually via npm, I just get another error about it missing another module, so I gave up at that point.

Expected behavior
Perform the get request and return the content of the requested web page.

[SebastianAigner]

Hey @FabianRohr! There is currently a known issue regarding transitive dependencies that we hope to address soon. In the meantime, the workaround is indeed to add NPM dependencies directly to your build file.
Check out this sample Gradle build file, which should contain all dependencies you need to get Ktor clients running in Kotlin/JS: https://github.com/kotlin-hands-on/jvm-js-fullstack/blob/master/build.gradle.kts#L72

[oleg-larshin]

Please check the following ticket on YouTrack for follow-ups to this issue. GitHub issues will be closed in the coming weeks.