# Swift for Wasm June 2026 Updates **URL:** \ **Category:** Swift for WebAssembly\ **Tags:** wasmkit, javascriptkit, emscripten, elementary\ **Created:** [June 29, 2026, 1:19pm UTC](https://forums.swift.org/t/swift-for-wasm-june-2026-updates/87820 "2026-06-29T13:19:17Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![Max\_Desiatov](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/max_desiatov/32/20654_2.png) [@Max\_Desiatov](https://forums.swift.org/u/Max_Desiatov)\ **Post date:** [June 29, 2026, 1:19pm UTC](https://forums.swift.org/t/swift-for-wasm-june-2026-updates/87820/1 "2026-06-29T13:19:17Z")
Notable changes this month: the [Swift.org](http://Swift.org) blog covered how Goodnotes shipped its app to the web with Swift and WebAssembly; Emscripten support improved in the Swift compiler, the standard library, and the test suite; JavaScriptKit shipped multiple releases (0.54.0–0.56.0) with substantial BridgeJS work; WasmKit 0.3.0 released, bringing initial Component Model support with three new Wasm proposals (SIMD, Atomics, Exception Handling); and ElementaryUI reached 0.4.0. Many thanks to @etcwilde, @jackguac, @kateinoigakukun, @krodak, @sliemeobn, @wfltaylor for contributions! ## Blog Posts - [Bringing Goodnotes to the Web with Swift and WebAssembly](https://www.swift.org/blog/bringing-goodnotes-to-web-with-swift/): Yuta Saito (@kateinoigakukun) explains how Goodnotes compiled its shared Swift code to WebAssembly with SwiftWasm, using JavaScriptKit for bidirectional Swift-JavaScript interop and WASI threads for high performance. ## Forum Discussions - [Wasm WebGPU State Machine Engine](https://forums.swift.org/t/a-swift-wasm-webgpu-state-machine-engine/87289): SwiftXState, an early-stage state-machine engine with a WebGPU proof-of-concept running Swift in the browser via Wasm. ## [Swift Toolchain](https://github.com/swiftlang/swift) On `main`, toolchain work this month mostly focused on improvements to Emscripten support: - `utils/build-script`: extract Wasm helpers from WASI-only products [swift#89549](https://github.com/swiftlang/swift/pull/89549); - `wasistdlib.py`: add `SILOptimizer` to lit test paths [swift#89420](https://github.com/swiftlang/swift/pull/89420); - CMake: add Emscripten build system configuration [swift#89768](https://github.com/swiftlang/swift/pull/89768); - `wasiswiftsdk`: put the toolchain version into the Swift SDK bundle name [swift#89841](https://github.com/swiftlang/swift/pull/89841); - Synchronization: use busywait when wasi-libc opts into busywait mode [swift#89829](https://github.com/swiftlang/swift/pull/89829); - Enable the lit test suite for `wasm32-unknown-emscripten` [swift#89806](https://github.com/swiftlang/swift/pull/89806); - stdlib: add an `EmscriptenLibc` overlay [swift#89797](https://github.com/swiftlang/swift/pull/89797); - Split ELF and Wasm Swift runtime registration files [swift#89930](https://github.com/swiftlang/swift/pull/89930); - stdlib: add necessary `EmscriptenLibc` conditions [swift#89799](https://github.com/swiftlang/swift/pull/89799); - Embedded: fix concurrency dynamic-isolation linker errors [swift#87877](https://github.com/swiftlang/swift/pull/87877); - Add tests for `swiftasyncc` tail calls on Wasm [swift#88074](https://github.com/swiftlang/swift/pull/88074); - Enable Emscripten in `LocalTestingDistributedActorSystem.swift` [swift#87797](https://github.com/swiftlang/swift/pull/87797); ## [JavaScriptKit](https://github.com/swiftwasm/JavaScriptKit) The most notable additions, landing across the [0.54.0](https://github.com/swiftwasm/JavaScriptKit/releases/tag/0.54.0)–[0.56.0](https://github.com/swiftwasm/JavaScriptKit/releases/tag/0.56.0) releases, were BridgeJS support for associated-value and case enums, throwing/async closures, and Swift doc comments carried through to the generated `.d.ts`. - Change `Data.construct(from uint8Array:)` return type from `Data?` to `Data` [#752](https://github.com/swiftwasm/JavaScriptKit/pull/752); - BridgeJS: support optional `@JS` struct in imported function signatures [#755](https://github.com/swiftwasm/JavaScriptKit/pull/755); - BridgeJS: support case enums as imported function parameters and returns [#756](https://github.com/swiftwasm/JavaScriptKit/pull/756); - BridgeJS: use a `BigInt` zero placeholder for Wasm i64 in generated JS [#757](https://github.com/swiftwasm/JavaScriptKit/pull/757); - BridgeJS: support non-`ConvertibleToJSValue` async exported return types [#758](https://github.com/swiftwasm/JavaScriptKit/pull/758); - BridgeJS: support optional `@JSClass` as exported function parameters [#754](https://github.com/swiftwasm/JavaScriptKit/pull/754); - Fix error descriptions for Embedded Swift compatibility [#759](https://github.com/swiftwasm/JavaScriptKit/pull/759); - BridgeJS: fix reject path of zero-parameter async throwing exports [#760](https://github.com/swiftwasm/JavaScriptKit/pull/760); - BridgeJS: support associated-value enums in import and async paths [#764](https://github.com/swiftwasm/JavaScriptKit/pull/764); - BridgeJS: support `throws` and `async` for closures [#766](https://github.com/swiftwasm/JavaScriptKit/pull/766); - BridgeJS: normalize Wasm pointer offsets in JS [#768](https://github.com/swiftwasm/JavaScriptKit/pull/768); - BridgeJS: emit static members in `declare global` class declarations [#772](https://github.com/swiftwasm/JavaScriptKit/pull/772); - BridgeJS: include Swift doc comments in generated `.d.ts` [#771](https://github.com/swiftwasm/JavaScriptKit/pull/771); - BridgeJS: export types using a separate JS representation [#750](https://github.com/swiftwasm/JavaScriptKit/pull/750); ## [WasmKit](https://github.com/swiftwasm/WasmKit) [WasmKit 0.3.0](https://github.com/swiftwasm/WasmKit/releases/tag/0.3.0) shipped with initial WebAssembly [Component Model](https://component-model.bytecodealliance.org) support behind a non-default `ComponentModel` package trait (a binary parser/encoder, `ComponentInstance`/`ComponentLoader`, and CLI invocation of simple components with WAVE-encoded arguments); three new core-Wasm proposals (Fixed-Width SIMD, Atomics, and Exception Handling); substantially expanded WASIp1 coverage (`poll_oneoff` timers, an in-memory file system, thread-safety, and fd-leak/IO fixes); and a move to typed throws via a unified `WasmKitError` coinciding with the minimum supported Swift version raised to 6.3. Notable changes merged in June: - Add support for the WebAssembly Exception Handling proposal [#311](https://github.com/swiftwasm/WasmKit/pull/311); - Represent Component Model valtypes as type index or inline primitive [#353](https://github.com/swiftwasm/WasmKit/pull/353); - Make `WASIBridgeToHost` thread-safe [#347](https://github.com/swiftwasm/WasmKit/pull/347); - Per-node locking for the in-memory WASI file system [#358](https://github.com/swiftwasm/WasmKit/pull/358); - Make `InstructionTranslator` non-copyable [#209](https://github.com/swiftwasm/WasmKit/pull/209); - `SystemExtras`: stop shadowing the C `stat` type (fixes build with swift-system 1.7.0) [#349](https://github.com/swiftwasm/WasmKit/pull/349); - Add `Sendable` conformance to `CatchClause` and `TryCatch` [#355](https://github.com/swiftwasm/WasmKit/pull/355); ## [ElementaryUI](https://github.com/elementary-swift/elementary-ui) [Version 0.4.0 released](https://github.com/elementary-swift/elementary-ui/releases/tag/0.4.0), upgrading to JavaScriptKit 0.55 and broadening the `swift-collections` dependency version range. As with 0.3.0, existing projects need to reinstall the bundled `BrowserRuntime` npm package and clear the Vite dev cache (see the release notes for the exact commands). - Upgrade to JavaScriptKit 0.55 [#108](https://github.com/elementary-swift/elementary-ui/pull/108); - Unpin `swift-collections` and bump to 1.6.0 [#107](https://github.com/elementary-swift/elementary-ui/pull/107); - Fix attributes without values [#110](https://github.com/elementary-swift/elementary-ui/pull/110); * * * Thank you for reading, and please feel free to add any comments or suggestions if we missed anything! If you'd like to catch up with changes from previous months, here's a list of relevant updates: - [May 2026](https://forums.swift.org/t/swift-for-wasm-may-2026-updates/86981); - [April 2026](https://forums.swift.org/t/swift-for-wasm-april-2026-updates/86371); - [March 2026](https://forums.swift.org/t/swift-for-wasm-march-2026-updates/85725); - [February 2026](https://forums.swift.org/t/swift-for-wasm-february-2026-updates/85046); - [January 2026](https://forums.swift.org/t/swift-for-wasm-january-2026-updates/84458).