I want to build wasm for Deno.

[kahirokunn]

💡 Feature description

I want to build wasm for Deno.
https://github.com/denoland/deno

I try write rust and do wasm-pack.
And then I got .wasm file, I put it file on the Deno.
But the wasm file never work....(´；ω；｀)

💻 Basic example

$ wasm-pack build --target deno

[csmoe]

wasm-pack's build target reiles on wasm-bindgen cc https://rustwasm.github.io/docs/wasm-bindgen/reference/cli.html?highlight=target#--target

[ibaryshnikov]

@kahirokunn is there require function in deno?

[ashleygwilliams]

related denoland/deno#1325

[ashleygwilliams]

@kahirokunn in order to run wasm-packed wasm, you'll need to require the js wrapper generated by wasm-bindgen. can deno load JS?

[kevinkassimo]

fyi Deno has resolved the original issue posted above and have also recently just introduced WASM imports (should be very similar to Node.js's --experimental-wasm-modules):

import { exportedFunc1, exportedFunc2 } from "./my.wasm";

If my.wasm imports from other JS/TS files, it could be done by specifying import names like

(module
  (import "./wasm-dep.js" "jsFn" (func $jsFn (result i32)))
  (import "http://127.0.0.1:4545/cli/tests/051_wasm_import/remote.ts" "jsRemoteFn" (func $jsRemoteFn (result i32)))
)

with corresponding local/remote file set up with correct named exports.

[ytoune]

I use below for a while

cargo generate --git https://github.com/rustwasm/wasm-pack-template -n myproject
cd myproject
# deno has not alert but has console.log.
sed -i -e "s/fn alert(s: &str);/#[wasm_bindgen(js_namespace = console, js_name = log)] fn alert(s: \\&str);/" src/lib.rs

wasm-pack build --target web --out-name index
# deno hasn't supported fetch('file:// ...') yet.
sed -i -e "s#input = import\\.meta\\.url\\.replace(/\\\\\\.js$/, '_bg\\.wasm');#input = import.meta.url.replace(/\\\\.js$/, '_bg.wasm'); if ('undefined' !== typeof Deno) input = new WebAssembly.Module(await Deno.readFile(new URL(input).pathname));#" pkg/index.js

echo "import * as pkg from './pkg/index.js'
await pkg.default()
pkg.greet()" >| app.js
deno run --allow-read app.js

denoland/deno#2150

[bsunderhus]

Just for future references of those who are still a little confused and end up in this opened issue.

To build for deno just build for web: wasm-pack build --target web

The only problem at the moment is that Deno doesn't support fetch for local files, and the web targeted build will try to get the .wasm binary with fetch, so to solve this when calling the initializing function from the generated package you'll have to manually pass the content extracted from the .wasm file

example:

import init, {greet} from "./pkg/greet.js";

await init(Deno.readFile('./pkg/greet_bg.wasm'));
greet();

[drager]

Fixed in v0.11.0.