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I want to pass through a file from JavaScript and get access to it as a u8 array in Rust WebAssembly. I have done this in Emscripten c++ buffer by allocating memory and passing pointer but I can't fathom it in RUST and wasm-bindgen.

Ian Knowles
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  • Possible duplicate of [How to read a file with JavaScript to WebAssembly using Rust?](https://stackoverflow.com/questions/51047146/how-to-read-a-file-with-javascript-to-webassembly-using-rust) – u32i64 Jun 20 '19 at 14:47

1 Answers1

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If you expose a function with an arg data: &[u8]

#[wasm_bindgen]
#[allow(non_snake_case)]
#[no_mangle]
pub fn processFile(fileData: &[u8])

You can pass a byte array to it from JavaScript

let fileData = new Uint8Array(23);
// populate data ...
mod.processFile(fileData)

Perhaps just with the version I'm using

λ wasm-pack -V
wasm-pack 0.8.1

Array length might be an issue, (my code has fixed length data) I would pass the len in the function and validate it because I'm not sure how rustc could validate that otherwise.

teknopaul
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