wasm-bindgen interface for working with read streams

[icidasset]

A wasm-bindgen interface for a private file's stream_content method. Ideally an equivalent on the public side should also exist.

Use case I had in mind:
Ability to use the HTTP range header to get a part of a file.

[matheus23]

Yes, that would be nice!

Ideally an equivalent on the public side should also exist.

Agreed, for us that's going to be more akin to integrating iroh-unixfs (now beetle-unixfs?). Or in webnative, we could do that today if we integrated with unixfs-exporter nicely.

[matheus23]

I started on some implementation recently, but ended up refocusing my efforts. Here's some useful resources:

• we likely want to use ReadableStreams on the JS side, and ReadableStreamBYOBReader to minimize copying.
• I don't know how I ended up there (I think going from ByobReader -> AsyncRead is the way to go), but I also found this useful in general, just in case there needs to be some stream-to-asyncread conversion somewhere: https://docs.rs/futures/latest/futures/stream/trait.TryStreamExt.html#method.into_async_read
• also useful are JsStream and JsFuture