esm: experimental wasm modules

lib/internal/modules/esm/default_resolve.js

@@ -10,7 +10,7 @@ const preserveSymlinks = getOptionValue('--preserve-symlinks');
 const preserveSymlinksMain = getOptionValue('--preserve-symlinks-main');
 const experimentalJsonModules = getOptionValue('--experimental-json-modules');
 const typeFlag = getOptionValue('--input-type');
-
+const experimentalWasmModules = getOptionValue('--experimental-wasm-modules');
 const { resolve: moduleWrapResolve,
         getPackageType } = internalBinding('module_wrap');
 const { pathToFileURL, fileURLToPath } = require('internal/url');
@@ -44,6 +44,16 @@ const legacyExtensionFormatMap = {
   '.node': 'commonjs'
 };
 
+if (experimentalWasmModules) {
+  // This is a total hack
+  Object.assign(extensionFormatMap, {
+    '.wasm': 'wasm'
+  });
+  Object.assign(legacyExtensionFormatMap, {
+    '.wasm': 'wasm'
+  });
+}
+
 if (experimentalJsonModules) {
   // This is a total hack
   Object.assign(extensionFormatMap, {

lib/internal/modules/esm/translators.js

@@ -1,9 +1,12 @@
 'use strict';
 
+/* global WebAssembly */
+
 const {
+  JSON,
+  Object,
   SafeMap,
-  StringPrototype,
-  JSON
+  StringPrototype
 } = primordials;
 
 const { NativeModule } = require('internal/bootstrap/loaders');
@@ -141,3 +144,37 @@ translators.set('json', async function jsonStrategy(url) {
     reflect.exports.default.set(module.exports);
   });
 });
+
+// Strategy for loading a wasm module
+translators.set('wasm', async function(url) {
+  const pathname = fileURLToPath(url);
+  const buffer = await readFileAsync(pathname);
+  debug(`Translating WASMModule ${url}`);
+  try {
+    const compiled = await WebAssembly.compile(buffer);
+    // Note: This approach executes dependencies early, and will
+    // deadlock in cycles, both of which will be resolved when
+    // top-level await support lands.
+    const loader = await esmLoader.loaderPromise;
+    const imports = Object.create(null);
+    await Promise.all(
+      WebAssembly.Module.imports(compiled).map(async (impt) => {
+        imports[impt.module] = await loader.import(impt.module, url);
+      })
+    );
+    const exportNames = WebAssembly.Module.exports(compiled)
+      .map((i) => i.name);
+    return createDynamicModule(exportNames, url, (reflect) => {
+      // Creating a wasm instance with the JS api will automatically
+      // run the wasm start function, so this must be done inside the
+      // dynamic module callback.
+      const { exports } = new WebAssembly.Instance(compiled, imports);
+      exportNames.forEach((name) => {
+        reflect.exports[name].set(exports[name]);
+      });
+    });
+  } catch (err) {
+    err.message = pathname + ': ' + err.message;
+    throw err;
+  }
+});

src/node_options.cc

@@ -269,6 +269,10 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             "experimental ES Module support and caching modules",
             &EnvironmentOptions::experimental_modules,
             kAllowedInEnvironment);
+  AddOption("--experimental-wasm-modules",
+            "experimental ES Module support for webassembly modules",
+            &EnvironmentOptions::experimental_wasm_modules,
+            kAllowedInEnvironment);
   AddOption("--experimental-policy",
             "use the specified file as a "
             "security policy",

src/node_options.h

@@ -94,6 +94,7 @@ class EnvironmentOptions : public Options {
   bool experimental_json_modules = false;
   bool experimental_modules = false;
   std::string es_module_specifier_resolution;
+  bool experimental_wasm_modules = false;
   std::string module_type;
   std::string experimental_policy;
   bool experimental_repl_await = false;

test/es-module/test-esm-wasm.mjs

@@ -0,0 +1,9 @@
+// Flags: --experimental-modules --experimental-wasm-modules
+/* eslint-disable node-core/required-modules */
+import { add, addImported } from '../fixtures/es-modules/simple.wasm';
+import { strictEqual } from 'assert';
+
+strictEqual(add(10, 20), 30);
+
+strictEqual(addImported(0), 42);
+strictEqual(addImported(1), 43);

test/fixtures/es-modules/wasm-dep.mjs

@@ -0,0 +1,3 @@
+export function jsFn () {
+  return 42;
+}