Merge pull request #1579 from ibaryshnikov/default-init-module

added default module path inside init function when target is web

crates/cli-support/src/js/mod.rs

@@ -450,6 +450,17 @@ impl<'a> Context<'a> {
         } else {
             ""
         };
+
+        let default_module_path = match self.config.mode {
+            OutputMode::Web => {
+                "\
+                    if (typeof module === 'undefined') {
+                        module = import.meta.url.replace(/\\.js$/, '_bg.wasm');
+                    }"
+            }
+            _ => "",
+        };
+
         let ts = Self::ts_for_init_fn(mem.import.is_some());
 
         // Initialize the `imports` object for all import definitions that we're
@@ -475,6 +486,7 @@ impl<'a> Context<'a> {
         let js = format!(
             "\
                 function init(module{init_memory_arg}) {{
+                    {default_module_path}
                     let result;
                     const imports = {{}};
                     {imports_init}
@@ -518,6 +530,7 @@ impl<'a> Context<'a> {
                 }}
             ",
             init_memory_arg = init_memory_arg,
+            default_module_path = default_module_path,
             init_memory1 = init_memory1,
             init_memory2 = init_memory2,
             start = if needs_manual_start {

examples/without-a-bundler/index.html

@@ -12,20 +12,23 @@
       // will "boot" the module and make it ready to use. Currently browsers
       // don't support natively imported WebAssembly as an ES module, but
       // eventually the manual initialization won't be required!
-      import { add, default as init } from './pkg/without_a_bundler.js';
+      import init, { add } from './pkg/without_a_bundler.js';
 
       async function run() {
         // First up we need to actually load the wasm file, so we use the
         // default export to inform it where the wasm file is located on the
         // server, and then we wait on the returned promise to wait for the
         // wasm to be loaded.
+        // It may look like this: `await init('./pkg/without_a_bundler_bg.wasm');`,
+        // but there is also a handy default inside `init` function, which uses
+        // `import.meta` to locate the wasm file relatively to js file
         //
         // Note that instead of a string here you can also pass in an instance
         // of `WebAssembly.Module` which allows you to compile your own module.
         // Also note that the promise, when resolved, yields the wasm module's
         // exports which is the same as importing the `*_bg` module in other
         // modes
-        await init('./pkg/without_a_bundler_bg.wasm');
+        await init();
 
         // And afterwards we can use all the functionality defined in wasm.
         const result = add(1, 2);