# 2019-09-11 rust meetup malaysia
# used with git.suckless.org/sent

Rust to NPM

Why Rust? (portable nodejs dev standpoint)
- zero cost abstractions
- no garbage collector
- safe (ReferenceError: x is not defined)

1. The WASM Way

Web Assembly
- binary
- compact

wasm-bindgen, js-sys, web-sys

IIRC (warning: hand-typed)

\#[wasm_bindgen]
extern crate {
    fn alert(msg: &str);
}
\
\#[wasm_bindgen]
fn hello(msg: &str) {
    alert(format!("hello {}", msg));
}

Tradition (the manual way)

$ rustup target add wasm32-unknown-unknown
$ cargo build --target=wasm32-unknown-unknown
$ ...
\# add a bunch of client boiler plate
\# use build target/wasm32-unknown-unknown

wasm-pack

- a helper to 'pack and publish your wasm!'
- browser or nodejs target but not much
- less enum power for error handling fallback
- simple api through `proc_macro`
- no full std support, eg. `format!` needed for wasm

$ wasm-pack build --target=nodejs --release
$ wasm-pack publish

2. Node.js bindings

neon

IIRC (warning: hand-typed)

\#[macro_use]
extern crate neon;
extern crate mycrate;
\
use neon::prelude::*;
\
fn hello(mut cx: FunctionContext) -> JsResult<JsString> {
    Ok(cx.string(format!("hello {}", cx.argument::<JsString>(0)?.value())))
}
\
register_module!(mut cx, {
    cx.export_function("hello", hello)
});

- expose some garbage collector stuff
- complicated and need to tweak code
- no wasm but dynamic lib (faster?)
- still need to write minimal js glue

$ neon build
\# neon does not have publish

Summary?