feat: import .wasm modules in service worker format workers

This allows importing `.wasm` modules in service worker format workers. We do this by hijacking imports to `.wasm` modules, and instead registering them under `[wasm_modules]` (building on the work from #409).

.changeset/ten-moons-develop.md

@@ -0,0 +1,7 @@
+---
+"wrangler": patch
+---
+
+feat: import `.wasm` modules in service worker format workers
+
+This allows importing `.wasm` modules in service worker format workers. We do this by hijacking imports to `.wasm` modules, and instead registering them under `[wasm_modules]` (building on the work from https://github.com/cloudflare/wrangler2/pull/409).

packages/example-wasm-app/README.md

@@ -1,9 +1,17 @@
 ## example-wasm-app
 
-There are 2 workers in this package. They were both created with a [`workers-rs`](https://github.com/cloudflare/workers-rs) project, running a build, removing unneeded artifacts, and copying the output folders.
+There are 3 workers in this package. They were created with a [`workers-rs`](https://github.com/cloudflare/workers-rs) project, running a build, removing unneeded artifacts, and copying the output folders.
 
-The wasm file generated, `index_bg.wasm` is copied into `./worker`, and shared by the 2 workers. `./worker/module` contains a "modules" format worker and imports the wasm module as a regular es module, while `./worker/service-worker` contains a "service-worker" format worker and uses wrangler.toml to bind the wasm module as a global `MYWASM`. They're otherwise identical.
+The wasm file generated, `index_bg.wasm` is copied into `./worker`, and shared by the 3 workers.
+
+- `./worker/module` contains a "modules" format worker and imports the wasm module as a regular es module.
+- `./worker/service-worker` contains a "service-worker" format worker and uses `wrangler.toml` to bind the wasm module as a global `MYWASM`.
+- `./worker/service-worker-module` contains a "service-worker" format worker and imports the wasm module as a regular es module.
+
+They're otherwise identical.
 
 You can run the module worker with `npx wrangler dev worker/module/index.js` (or from the `wrangler` package directory with `npm start -- dev ../example-wasm-app/worker/module/index.js`).
 
 You can run the service-worker worker with `npx wrangler dev worker/service-worker/index.js --config worker/service-worker/wrangler.toml` (or from the `wrangler` package directory with `npm start -- dev ../example-wasm-app/worker/service-worker/index.js --config ../example-wasm-app/worker/service-worker/wrangler.toml`).
+
+You can run the service-worker-module worker with `npx wrangler dev worker/service-worker-module/index.js` (or from the `wrangler` package directory with `npm start -- dev ../example-wasm-app/worker/service-worker-module/index.js`).

packages/example-wasm-app/worker/service-worker-module/export_wasm.js

@@ -0,0 +1,10 @@
+import * as index_bg from "./index_bg.js";
+import _wasm from "../index_bg.wasm";
+
+const _wasm_memory = new WebAssembly.Memory({ initial: 512 });
+let importsObject = {
+  env: { memory: _wasm_memory },
+  "./index_bg.js": index_bg,
+};
+
+export default new WebAssembly.Instance(_wasm, importsObject).exports;

packages/example-wasm-app/worker/service-worker-module/index.js

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+import * as worker from "./index_bg.js";
+
+addEventListener("fetch", (event) => {
+  event.respondWith(worker.fetch(event.request));
+});