GraalVM announced preliminary WASM target

[ScraM-Team]

The GraalVM team demoed Java bytecode to WASM compilation at wasm.io, via their 'native-image' tool. The slides are here: https://2025.wasm.io/slides/the-future-of-write-once-run-anywhere-from-java-to-webassembly-wasmio25.pdf

To me, Slide 7 shows just how much work they still have to catch TeaVM:

• 1MB Hello World size
• No threading
• No networking
• No graphics (not sure if they mean AWT or native browser graphics)

The slides discuss some design choices they made to work within WASM constraints.

There is no sign they plan a JavaScript target.

[konsoletyper]

Yes, I know.

No threading

TeaVM Wasm GC does not have threading yet as well. And JS version does not support fair threading, but emulation over coroutines.

No graphics (not sure if they mean AWT or native browser graphics)

Sure they mean AWT. They provide some interop API (@JS annotation, much like @JSBody, but it's everything they have), so you can in theory build UI calling DOM via interop.

There is no sign they plan a JavaScript target.

And they don't need it. If you have Wasm GC target, why would you need JavaScript? I also was going to drop JS BE eventually (not quite soon yet).

I would add my points:

• How long does it take to produce an image?
• Do they provide fair stack traces?
• What about performance?
• Is there a way to quickly rebuild an image?
• Where's the documentation?
• What about tooling: Maven, Gradle, debugging?

Anyway, I'm afraid TeaVM won't survive after this. I see all these "wow, at last we can run Java in the browser", as if it was not possible all these years. Being a large company is always a winning strategy.

Also I'd mention that once I attempted to get a job in GraalVM team and got a refusal because "I'm not good enough". So what do "good enough" guys do? With all possible support, full-time job of several employees they end up with a tool that produces 1MB Hello World?

[ScraM-Team]

You should feel proud of TeaVM, Alexey! I posted about GraalVM mainly to "know thy enemy". I still think TeaVM is better in just about every respect, and I gave many examples. My donations continue and I hope you stay excited about this incredible project. I use numerous TeaVM-powered apps every day.

Many Java to JavaScript AOT tools have come and gone, yet TeaVM still stands strong! Look at this trail of would-be competitors, now idle or fading compared to TeaVM's 2.8k stars:

• J2CL: 1.3k stars
• JSweet: 1.5k stars
• Bytecoder: 0.9k stars

I will keep evangelizing for TeaVM. I know others here will too. Thank you, Alexey!