Update to Kotlin 1.9.22 and migrate to Kotlin/Wasm

README.md

@@ -15,13 +15,13 @@ Further documentation for Wrangler can be found [here](https://developers.cloudf
 After setting up Kotlin per the linked instructions above,
 
 ```
-./gradlew :compileProductionExecutableKotlinJs
+./gradlew :compileProductionExecutableKotlinWasmJs
 ```
 
 That will compile your code and package it into a JavaScript executable, after which you can run `wrangler publish` to push it to Cloudflare.
 
 ```
-wrangler publish build/js/packages/kotlin-worker-hello-world/kotlin/kotlin-worker-hello-world.js
+wrangler publish build/js/packages/kotlin-worker-hello-world-wasm-js/kotlin/kotlin-worker-hello-world-wasm-js.mjs
 ```
 
 For more information on interop between Kotlin and Javascript, see the [Kotlin docs](https://kotlinlang.org/docs/reference/js-interop.html).  Regarding coroutines, see [this issue and workaround](https://github.com/cloudflare/kotlin-worker-hello-world/issues/2)

build.gradle.kts

@@ -1,5 +1,8 @@
+import org.jetbrains.kotlin.gradle.targets.js.nodejs.NodeJsRootExtension
+import org.jetbrains.kotlin.gradle.targets.js.npm.tasks.KotlinNpmInstallTask
+
 plugins {
-    kotlin("js") version "1.7.10"
+    kotlin("multiplatform") version "1.9.22"
 }
 
 group = "org.example"
@@ -10,9 +13,21 @@ repositories {
 }
 
 kotlin {
-    js(IR) {
+    wasmJs {
         nodejs {
         }
         binaries.executable()
+
+        // Uncomment the next line to apply Binaryen and get optimized wasm binaries
+        // applyBinaryen()
     }
 }
+
+// To run in Node.js
+rootProject.the<NodeJsRootExtension>().apply {
+    nodeVersion = "22.0.0-nightly2024021536dcd399c0"
+    nodeDownloadBaseUrl = "https://nodejs.org/download/nightly"
+}
+tasks.withType<KotlinNpmInstallTask>().configureEach {
+    args.add("--ignore-engines")
+}

src/main/kotlin/main.kt → src/wasmJsMain/kotlin/main.kt

@@ -1,14 +1,15 @@
+import org.w3c.fetch.Headers
 import org.w3c.fetch.Request
 import org.w3c.fetch.Response
 import org.w3c.fetch.ResponseInit
 
 @OptIn(ExperimentalJsExport::class)
 @JsExport
 fun fetch(request: Request) : Response {
-    val headers: dynamic = object {}
-    headers["content-type"] = "text/plain"
+    val headers = Headers()
+    headers.append("content-type", "text/plain")
     return Response(
-        "Kotlin Worker hello world",
+        "Kotlin Worker hello world".toJsString(),
         ResponseInit(headers = headers)
     )
 }