fix: provide module/exports in VM sandbox for Node.js 25+ compatibility

Marukome0743 · Marukome0743 · commit 02d68f847fd1 · 2026-04-17T23:15:51.000+09:00
Templates whose child compilation output is a CommonJS module (for example Rspack's HtmlWebpackPlugin child compilation, which wraps the evaluated template in `module.exports = ...`) were failing at evaluation time with `ReferenceError: module is not defined` under Node.js 25+. In 5.6.5 the VM context was switched away from a `...global` spread because spreading `global` on Node 25 throws once `localStorage` is touched without `--localstorage-file`. The replacement clone only exposes the standard globals plus `require`, so any CommonJS-wrapped source that assigned to `module.exports` hit the ReferenceError. Provide a throwaway `module = { exports: {} }` pair (plus `exports` aliasing it) in the sandbox so CommonJS-style outputs can evaluate without assuming the host Node version populates them. Refs: PR jantimon#1880, facebook/docusaurus#11545
diff --git a/.cspell.json b/.cspell.json
@@ -28,7 +28,8 @@
     "specialattribute",
     "dircompare",
     "wagoid",
-    "autocrlf"
+    "autocrlf",
+    "Rspack"
   ],
   "ignorePaths": [
     "CHANGELOG.md",
diff --git a/index.js b/index.js
@@ -640,11 +640,17 @@ class HtmlWebpackPlugin {
     delete globalClone.eval;
     delete globalClone.Function;
     // Not using `...global` as it throws when localStorage is not explicitly enabled in Node 25+
+    // Provide a CommonJS-style `module`/`exports` pair so templates compiled as CommonJS
+    // (e.g. Rspack's child compilation output, which wraps the result in `module.exports = ...`)
+    // can assign to them instead of failing with `module is not defined`.
+    const sandboxModule = { exports: {} };
     const vmContext = vm.createContext(
       Object.assign(globalClone, {
         HTML_WEBPACK_PLUGIN: true,
         // Copying nonstandard globals like `require` explicitly as they may be absent from `global`
         require: require,
+        module: sandboxModule,
+        exports: sandboxModule.exports,
         htmlWebpackPluginPublicPath: publicPath,
         __filename: templateWithoutLoaders,
         __dirname: path.dirname(templateWithoutLoaders),
diff --git a/spec/basic.spec.js b/spec/basic.spec.js
@@ -3853,4 +3853,16 @@ describe("HtmlWebpackPlugin", () => {
       done,
     );
   });
+
+  describe("evaluateCompilationResult", () => {
+    it("evaluates templates wrapped in a CommonJS `module.exports = ...` expression", () => {
+      const plugin = new HtmlWebpackPlugin();
+      const source = 'module.exports = "<!DOCTYPE html><title>ok</title>";';
+      return plugin
+        .evaluateCompilationResult(source, "", "template.js")
+        .then((result) => {
+          expect(result).toBe("<!DOCTYPE html><title>ok</title>");
+        });
+    });
+  });
 });
