[WASM] Run WebAssembly in Node.js using the node-loader

WebAssembly is great for targeting performance bottlenecks in the browser. Now with node-loader, we can do the same on the server through Node.js

While Node offers also bindings to native extensions for C/C++ via node-gyp, there was no straight forward way to write Rust extensions. In addition did the node-gyp API change often and developers had to be careful to make their C/C++ code work with various operating systems.

Compiling Rust to WebAssembly solves both of these issues. The API is stable and once compiled to WebAssembly it will run on every operating system supported by Node.

Since Node doesn't support loading .wasm files a loader is needed. The loader flag though is only supported when using the --experimental-modules flag in Node 10 or higher.

Install:

npm i --save @wasm-tool/node

Run:

cargo new crate --name=utils --lib

Cargo.toml:

[package]
name = "utils"
version = "0.1.0"
authors = ["zhentian-wan <answer881215@gmail.com>"]
edition = "2018"

[lib]
crate-type = ["cdylib"]

[dependencies]

Build:

cd crate
cargo build --target wasm32-unknown-unknown --release

Create js file:

index.mjs

import { add_one } from "./crate/target/wasm32-unknown-unknown/release/output.wasm"

console.log(add_one(1));
console.log(add_one(41));

Run:

node --experimental-modules --loader @wasm-tool/node index.mjs