web-message 0.0.2

A crate for sending and receiving messages via postMessage.

Any type that implements [Message] can be serialized and unserialized. Unlike using Serde for JSON encoding, this approach preserves Transferable Objects and can avoid expensive allocations and copying. Unlike using #[wasm-bindgen], this approach works outside of the wasm-bindgen ABI, supporting more types (ex. named enum variants).

For example, the main thread can send a [js_sys::ArrayBuffer] or a Web Worker without copying the data. If the WASM worker only needs to process a few header bytes, it can use the [js_sys::ArrayBuffer] instead of copying into a [Vec]. The resulting bytes can then be passed to VideoDecoder and the resulting VideoFrame (transferable) can be posted back to the main thread. You can even pass around a [web_sys::MessagePort]!

This crate is designed to be used in conjunction with the web-message-derive crate. We currently attempt parity with ts-rs so the resulting types can use postMessage directly from Typescript.

// NOTE: This is not possible with `wasm-bindgen` or `wasm-bindgen-serde`
#[derive(Message)]
#[msg(tag = "command")]
enum Command {
    Connect {
        url: String,
    },
    Frame {
        keyframe: bool,
        payload: js_sys::ArrayBuffer,
    },
    Close,
}

Some transferable types are gated behind feature flags: