Converting JsValue to Vec<u8>

Question

I need to use web_sys::Blob::array_buffer which returns a Promise that resolves to an ArrayBuffer. Promise currently only resolves to JsValue in Rust. How do I convert that to Vec<u8>?

Answer 1

First you must convert it to Uint8Array with Uint8Array::new which takes a &JsValue.

Then you can use:

• Uint8Array::to_vec to get a Vec<u8>
• Uint8Array::copy_to to fill an existing &mut [u8] of the same size

let buffer: JsValue = /* ... */;
let array = Uint8Array::new(&buffer);
let bytes: Vec<u8> = array.to_vec();