feat: added support for wasm2js

This is *extremely* preliminary, and Perseus provides almost no support
for this. This just makes the server integrations host a
`bundle.wasm.js` file, there is no inbuilt facility for transpiling from
Wasm to JS.

Author: arctic-hen7

examples/basic/.perseus/server/src/main.rs

@@ -116,6 +116,8 @@ fn get_props(is_standalone: bool) -> ServerProps<impl MutableStore, impl Transla
         js_bundle: "dist/pkg/perseus_engine.js".to_string(),
         // Our crate has the same name, so this will be predictable
         wasm_bundle: "dist/pkg/perseus_engine_bg.wasm".to_string(),
+        // This probably won't exist, but on the off chance that the user needs to support older browsers, we'll provide it anyway
+        wasm_js_bundle: "dist/pkg/perseus_engine_bg.wasm.js".to_string(),
         // It's a nightmare to get the templates map to take plugins, so we use a self-contained version
         // TODO reduce allocations here
         templates_map: get_templates_map_atomic_contained(),

packages/perseus-actix-web/src/configurer.rs

@@ -20,6 +20,9 @@ async fn js_bundle(opts: web::Data<Rc<ServerOptions>>) -> std::io::Result<NamedF
 async fn wasm_bundle(opts: web::Data<Rc<ServerOptions>>) -> std::io::Result<NamedFile> {
     NamedFile::open(&opts.wasm_bundle)
 }
+async fn wasm_js_bundle(opts: web::Data<Rc<ServerOptions>>) -> std::io::Result<NamedFile> {
+    NamedFile::open(&opts.wasm_js_bundle)
+}
 async fn static_alias(
     opts: web::Data<Rc<ServerOptions>>,
     req: HttpRequest,
@@ -79,6 +82,7 @@ pub async fn configurer<M: MutableStore + 'static, T: TranslationsManager + 'sta
             // This contains everything in the spirit of a pseudo-SPA
             .route("/.perseus/bundle.js", web::get().to(js_bundle))
             .route("/.perseus/bundle.wasm", web::get().to(wasm_bundle))
+            .route("/.perseus/bundle.wasm.js", web::get().to(wasm_js_bundle))
             // This allows getting the static HTML/JSON of a page
             // We stream both together in a single JSON object so SSR works (otherwise we'd have request IDs and weird caching...)
             // A request to this should also provide the template name (routing should only be done once on the client) as a query parameter

packages/perseus-warp/src/perseus_routes.rs

@@ -48,6 +48,9 @@ pub async fn perseus_routes<M: MutableStore + 'static, T: TranslationsManager +
     let wasm_bundle = warp::path!(".perseus" / "bundle.wasm")
         .and(warp::path::end())
         .and(warp::fs::file(opts.wasm_bundle.clone()));
+    let wasm_js_bundle = warp::path!(".perseus" / "bundle.wasm.js")
+        .and(warp::path::end())
+        .and(warp::fs::file(opts.wasm_js_bundle.clone()));
     // Handle JS interop snippets (which need to be served as separate files)
     let snippets = warp::path!(".perseus" / "snippets").and(warp::fs::dir(opts.snippets.clone()));
     // Handle static content in the user-set directories (this will all be under `/.perseus/static`)
@@ -121,6 +124,7 @@ pub async fn perseus_routes<M: MutableStore + 'static, T: TranslationsManager +
     // Now put all those routes together in the final thing (the user will add this to an existing Warp server)
     js_bundle
         .or(wasm_bundle)
+        .or(wasm_js_bundle)
         .or(snippets)
         .or(static_dir)
         .or(static_aliases)

packages/perseus/src/server/html_shell.rs

@@ -61,6 +61,8 @@ impl<'a> HtmlShell<'a> {
         }
 
         // Define the script that will load the Wasm bundle (inlined to avoid unnecessary extra requests)
+        // If we're using the `wasm2js` feature, this will try to load a JS version instead (expected to be at `/.perseus/bundle.wasm.js`)
+        #[cfg(not(feature = "wasm2js"))]
         let load_wasm_bundle = format!(
             r#"
         import init, {{ run }} from "{path_prefix}/.perseus/bundle.js";
@@ -72,6 +74,18 @@ impl<'a> HtmlShell<'a> {
         "#,
             path_prefix = path_prefix
         );
+        #[cfg(feature = "wasm2js")]
+        let load_wasm_bundle = format!(
+            r#"
+        import init, {{ run }} from "{path_prefix}/.perseus/bundle.js";
+        async function main() {{
+            await init("{path_prefix}/.perseus/bundle.wasm.js");
+            run();
+        }}
+        main();
+        "#,
+            path_prefix = path_prefix
+        );
         scripts_before_boundary.push(load_wasm_bundle.into());
 
         // Add in the `<base>` element at the very top so that it applies to everything in the HTML shell

packages/perseus/src/server/options.rs

@@ -15,6 +15,8 @@ pub struct ServerOptions {
     pub js_bundle: String,
     /// The location on the filesystem of your Wasm bundle.
     pub wasm_bundle: String,
+    /// The location on the filesystem of your JS bundle converted from your Wasm bundle. This isn't required, and if you haven't generated this, you should provide a fake path.
+    pub wasm_js_bundle: String,
     /// The location on the filesystem of your `index.html` file.
     // TODO Should this actually be a raw string of HTML so plugins can inject efficiently?
     pub index: String,