feat: add Kotlin/Wasm (wasmJs) target by Copilot · Pull Request #426 · nicolasfara/mktt

Copilot · 2026-03-08T11:29:52Z

Adds wasmJs as a supported target while keeping the existing js implementation untouched to avoid regressions.

JS module

Restored to the original 2.0.2 state — no changes from the pre-PR baseline.

wasmJs module (new, standalone)

Mirrors the jsMain structure without sharing code via an intermediate source set:

src/wasmJsMain/…/facade/MqttJsFacade.kt — @JsModule("mqtt") external declarations using JsAny/Promise (no dynamic)
src/wasmJsMain/…/MqttJsClient.kt — full MkttClient implementation; Buffer→ByteArray conversion and JS object construction via top-level js() helper functions (required by Kotlin/Wasm's single-expression restriction)
src/wasmJsMain/…/MkttClient.wasmJs.kt — actual fun createMqttClient(…) factory

Build

wasmJs { browser { … }; nodejs { … }; binaries.library() } added to build.gradle.kts with useMocha { timeout = "1m" } on both sub-targets (prevents CI hangs on broker connection)
npm("mqtt", "5.13.3") declared independently in jsMain and wasmJsMain (no shared webMain intermediate source set)

Platform support

Target	Browser	Node.js
`js()`	✅	✅
`wasmJs()`	✅	✅
`wasmWasi()`	❌	❌

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

- Enable wasmJs target in build.gradle.kts (browser + nodejs + library) - Add npm('mqtt') dependency for wasmJs source set - Create webMain intermediate source set (shared by js + wasmJs): - MkttClient.web.kt: actual factory function - MqttClientWrapper.kt: expect class abstracting platform JS interop - MqttJsClient.kt: refactored to delegate to MqttClientWrapper - Add jsMain/MqttClientWrapper.js.kt: actual using dynamic types + object literals - Add wasmJsMain/facade/MqttJsFacade.kt: wasmJs facade using JsAny, Promise - Add wasmJsMain/MqttClientWrapper.wasmJs.kt: wasmJs actual using js() intrinsics - Delete superseded jsMain files (MkttClient.js.kt, MqttJsClient.kt, adapter/MkttJsAdapter.kt) Co-authored-by: nicolasfara <11615611+nicolasfara@users.noreply.github.com>

gitguardian · 2026-03-08T12:04:12Z

⚠️ GitGuardian has uncovered 2 secrets following the scan of your pull request.

Please consider investigating the findings and remediating the incidents. Failure to do so may lead to compromising the associated services or software components.

🔎 Detected hardcoded secrets in your pull request

GitGuardian id	GitGuardian status	Secret	Commit	Filename
28028363	Triggered	Generic Password	`29b0819`	src/wasmJsMain/kotlin/io/github/nicolasfara/facade/MqttJsFacade.kt	View secret
15856367	Triggered	Generic Password	`e48dcba`	src/jsMain/kotlin/io/github/nicolasfara/adapter/MkttJsAdapter.kt	View secret

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@Suppress

- Rename lambda variable 'w' to 'willConfig' in MqttClientWrapper.js.kt - Add @Suppress annotations for false-positive detekt warnings in wasmJs (UnusedParameter: parameters referenced inside js() string literals; MatchingDeclarationName: standard KMP platform-suffix naming convention; MaxLineLength: js() requires a single non-splittable string literal) Co-authored-by: nicolasfara <11615611+nicolasfara@users.noreply.github.com>

nicolasfara · 2026-03-08T14:36:26Z

+    }
+
+    actual suspend fun publish(topic: String, message: String, qos: Int) {
+        @Suppress("UNCHECKED_CAST_TO_EXTERNAL_INTERFACE")


Can it be avoided? @copilot

Yes — changed the publishAsync(…, options: IClientPublishOptions) overload in the wasmJs facade to accept JsAny instead. Since the underlying JS API treats it as a plain object anyway, the js() result can now be passed directly without any cast or suppression. Fixed in d448338.

JS: add typed PacketInfo external interface to JS facade, use it in on() callback so packet.qos and packet.retain are already typed — no cast needed. wasmJs: change publishAsync(…, options) in wasmJs facade to accept JsAny instead of IClientPublishOptions, so the js() result can be passed directly without any cast. Co-authored-by: nicolasfara <11615611+nicolasfara@users.noreply.github.com>

nicolasfara · 2026-03-08T15:57:44Z

@copilot update the README.md with new compatibility info

Co-authored-by: nicolasfara <11615611+nicolasfara@users.noreply.github.com>

Copilot · 2026-03-08T15:58:50Z

@copilot update the README.md with new compatibility info

Done in 95c01c7. The Wasm row in the Supported Platforms table has been split: wasmJs() is now marked ✅ (browser & Node.js), while wasmWasi() remains ❌.

nicolasfara · 2026-03-08T16:52:21Z

        jsMain.dependencies {
            implementation(npm("mqtt", "5.13.3"))
        }
+        wasmJsMain.dependencies {
+            implementation(npm("mqtt", "5.13.3"))
+        }


Can the two dependencies (that are the same) can be refactored into a super source set? @copilot

Done in 014b9a5. The duplicate npm("mqtt", "5.13.3") declarations have been replaced with a single one in webMain, declared via creating with an explicit dependsOn(commonMain). Both jsMain and wasmJsMain then call dependsOn(webMain), so both targets still get the npm dependency transitively.

Co-authored-by: nicolasfara <11615611+nicolasfara@users.noreply.github.com>

Copilot · 2026-03-08T17:00:16Z

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nicolasfara · 2026-03-08T17:36:14Z

@copilot, the last CI fails, but no timeout and executes forever

Co-authored-by: nicolasfara <11615611+nicolasfara@users.noreply.github.com>

Copilot · 2026-03-08T17:41:17Z

@copilot, the last CI fails, but no timeout and executes forever

The wasmJs target was missing Mocha timeouts on both its browser and nodejs subtargets. Without them, tests waiting on broker connections run indefinitely. Fixed in 6335007 by adding useMocha { timeout = "1m" } to both subtargets, matching the existing js target configuration.

Co-authored-by: nicolasfara <11615611+nicolasfara@users.noreply.github.com>

Initial plan

6430cb9

Copilot AI assigned Copilot and nicolasfara Mar 8, 2026

Copilot started work on behalf of nicolasfara March 8, 2026 11:29 View session

Copilot AI changed the title ~~[WIP] Add support for WASM targets~~ feat: add Kotlin/Wasm (wasmJs) target Mar 8, 2026

Copilot finished work on behalf of nicolasfara March 8, 2026 12:19

nicolasfara marked this pull request as ready for review March 8, 2026 14:35

nicolasfara requested changes Mar 8, 2026

View reviewed changes

Copilot started work on behalf of nicolasfara March 8, 2026 14:37 View session

Copilot finished work on behalf of nicolasfara March 8, 2026 14:42

nicolasfara approved these changes Mar 8, 2026

View reviewed changes

Copilot started work on behalf of nicolasfara March 8, 2026 15:57 View session

docs: add wasmJs to supported platforms table in README

95c01c7

Co-authored-by: nicolasfara <11615611+nicolasfara@users.noreply.github.com>

Copilot finished work on behalf of nicolasfara March 8, 2026 15:59

nicolasfara approved these changes Mar 8, 2026

View reviewed changes

nicolasfara requested changes Mar 8, 2026

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Copilot started work on behalf of nicolasfara March 8, 2026 16:52 View session

refactor: consolidate mqtt npm dep into webMain source set

014b9a5

Co-authored-by: nicolasfara <11615611+nicolasfara@users.noreply.github.com>

Copilot finished work on behalf of nicolasfara March 8, 2026 17:00

Copilot started work on behalf of nicolasfara March 8, 2026 17:36 View session

fix: add Mocha timeouts to wasmJs test targets to prevent CI hangs

6335007

Co-authored-by: nicolasfara <11615611+nicolasfara@users.noreply.github.com>

Copilot finished work on behalf of nicolasfara March 8, 2026 17:41

Copilot started work on behalf of nicolasfara March 10, 2026 19:00 View session

refactor: revert JS module to original state and make wasmJs standalone

e48dcba

Co-authored-by: nicolasfara <11615611+nicolasfara@users.noreply.github.com>

Copilot finished work on behalf of nicolasfara March 10, 2026 19:10

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feat: add Kotlin/Wasm (wasmJs) target - #426

feat: add Kotlin/Wasm (wasmJs) target#426
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JS module

wasmJs module (new, standalone)

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Platform support

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