Support wasm-pack frontend in mdBook

[titaneric]

This PR aim to solve #1500.

Change of code

• Add new run_wasm_pack_code function in theme/book.js to fetch wasm-pack results and rendering them in Iframe
• Support wasm className in theme/book.js to differentiate the normal Rust and Wasm code
• Add new theme/iframe.html and theme/wasm-entry.mjs for Iframe
• Move iframe.html and wasm-entry.mjs to built directory by Rust

Note

• This implementation is different than Support wasm-pack frontend rust-playground#707
• It's possible to avoid new iframe.html and wasm-entry.mjs if we adapt their method, but the real implementation needs to be discussed.

Demo

2021-04-15.11-29-30.mp4

P.S.

This implementation is more like prototype than production, feel free to point out where I could do better or rewrite suitibly.

[titaneric]

Hi, I have already served my own rust-playground with wasm-pack feature, perhaps it's ready to be reviewed now.

[ehuss]

Sorry, I'm maybe a little confused on what this is doing. Has the corresponding PR been accepted by integer32? Have they committed to allowing that endpoint to be used by public tools? I probably won't review until they commit to it. If you're proposing to use a new service, I unfortunately probably won't accept that. I think I would prefer making the backend more configurable (#350), so that books can define their own (maybe through some kind of theme files?), but that would need some design work.

[titaneric]

Yes, #350 would be the better solution when it comes to plenty of available backends.
I do propose a new service to let user to try wasm-pack on the mdBook, and the real backend in rust-playground is still under PR and haven't been reviewed yet. Perhaps I could try #350 first and let someone could use my own service.
Thanks for your comment and I may closed it until #350 is been implemented.