WASM with ffi arrays

Hi! If I have a JS array and want to pass it to Rust/WASM and return it (modified), how do I do that? When using arrays I only get undefined. :frowning: If it helps I can my code

Does that help?

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hmm. Big thanks for your reply, @hellow! :slight_smile: But I would like to avoid wasm-bindgen. I seem to me that FFI is more small scale, more ‘light-weight’ than wasm-bindgen. Do you by any chance have and good ideas? I think it should be possible when I read the documentation, just can’t figure out how… :frowning: :slight_smile:

Wasm-bindgen should be the lightest possible thing that works.


Ah, ok. Sorry! Did not know that. :slight_smile: I thought that it was way larger… will look into that then! Hmm… perhaps I thought that, because you can (right?) generate stuff (elements and so on) directly into the browser. This lib is only for the ‘communication’ in-between, I think. I am a bit new to this. :slight_smile: Really think it is very fun to play around with anyways! :slight_smile:

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yes, bindgen is purely for generating your own bindings between javascript and rust code;

you might have had it mixed up with web-sys which more or less wraps all web APIs using bindgen which is somewhat heavier but handy if you want to avoid writing javascript completely


nice! thank to you both for clearing this up for me! :slight_smile:

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@hellow Hello, This does help a bit. But in my case I want to return same Vec (with transformed values) from rust (wasm) to JS.

Please start a new thread, optionally linking to this one, instead of reviving a year old thread.


@alice Well, Not required.. I got the answer from https://rustwasm.github.io/docs/wasm-bindgen/reference/arbitrary-data-with-serde.html