fix: refactor browser external proxy module to avoid missing export error

Author: underfin

packages/vite/src/node/plugins/resolve.ts

@@ -447,15 +447,26 @@ export function resolvePlugin(resolveOptions: InternalResolveOptions): Plugin {
     load(id) {
       if (id.startsWith(browserExternalId)) {
         if (isProduction) {
-          return `export default {}`
+          // return `export default {}`
+          // The rolldown missing export is always error level, it will break build.
+          // So here using the cjs module to avoid it.
+          return `module.exports = {}`
         } else {
           id = id.slice(browserExternalId.length + 1)
+          // The rolldown using esbuild interop helper, so here copy the proxy module from https://github.com/vitejs/vite/blob/main/packages/vite/src/node/optimizer/esbuildDepPlugin.ts#L259
           return `\
-export default new Proxy({}, {
+module.exports = Object.create(new Proxy({}, {
   get(_, key) {
-    throw new Error(\`Module "${id}" has been externalized for browser compatibility. Cannot access "${id}.\${key}" in client code.  See https://vitejs.dev/guide/troubleshooting.html#module-externalized-for-browser-compatibility for more details.\`)
+    if (
+      key !== '__esModule' &&
+      key !== '__proto__' &&
+      key !== 'constructor' &&
+      key !== 'splice'
+    ) {
+      throw new Error(\`Module "${id}" has been externalized for browser compatibility. Cannot access "${id}.\${key}" in client code.  See https://vitejs.dev/guide/troubleshooting.html#module-externalized-for-browser-compatibility for more details.\`)
+    }
   }
-})`
+}))`
         }
       }
       if (id.startsWith(optionalPeerDepId)) {

playground/optimize-deps/vite.config.js

@@ -62,8 +62,8 @@ export default defineConfig({
     minify: false,
     rollupOptions: {
       onwarn(msg, warn) {
-        // filter `"Buffer" is not exported by "__vite-browser-external"` warning
-        if (msg.message.includes('Buffer')) return
+        // // filter `"Buffer" is not exported by "__vite-browser-external"` warning
+        // if (msg.message.includes('Buffer')) return
         warn(msg)
       },
     },
@@ -97,19 +97,20 @@ export default defineConfig({
         }
       },
     },
-    // TODO: Remove this one support for prebundling in build lands.
-    // It is expected that named importing in build doesn't work
-    // as it incurs a lot of overhead in build.
-    {
-      name: 'polyfill-named-fs-build',
-      apply: 'build',
-      enforce: 'pre',
-      load(id) {
-        if (id === '__vite-browser-external') {
-          return `export default {}; export function readFileSync() {}`
-        }
-      },
-    },
+    // Remove this one because the resolve plugin already handle '__vite-browser-external'
+    // // TODO: Remove this one support for prebundling in build lands.
+    // // It is expected that named importing in build doesn't work
+    // // as it incurs a lot of overhead in build.
+    // {
+    //   name: 'polyfill-named-fs-build',
+    //   apply: 'build',
+    //   enforce: 'pre',
+    //   load(id) {
+    //     if (id === '__vite-browser-external') {
+    //       return `export default {}; export function readFileSync() {}`
+    //     }
+    //   },
+    // },
   ],
 })