fix: externalize dependencies by default during SSR

Author: benmccann

packages/vite/src/node/ssr/ssrExternal.ts

@@ -1,14 +1,7 @@
-import fs from 'fs'
 import path from 'path'
 import type { InternalResolveOptions } from '../plugins/resolve'
 import { tryNodeResolve } from '../plugins/resolve'
-import {
-  createDebugger,
-  isDefined,
-  lookupFile,
-  normalizePath,
-  resolveFrom
-} from '../utils'
+import { createDebugger, isDefined, lookupFile, resolveFrom } from '../utils'
 import type { Logger, ResolvedConfig } from '..'
 import { createFilter } from '@rollup/pluginutils'
 
@@ -79,9 +72,6 @@ export function resolveSSRExternal(
   return externals
 }
 
-const CJS_CONTENT_RE =
-  /\bmodule\.exports\b|\bexports[.\[]|\brequire\s*\(|\bObject\.(defineProperty|defineProperties|assign)\s*\(\s*exports\b/
-
 // do we need to do this ahead of time or could we do it lazily?
 function collectExternals(
   root: string,
@@ -115,7 +105,6 @@ function collectExternals(
     seen.add(id)
 
     let esmEntry: string | undefined
-    let requireEntry: string
     try {
       esmEntry = tryNodeResolve(
         id,
@@ -125,9 +114,6 @@ function collectExternals(
         undefined,
         true
       )?.id
-      // normalizePath required for windows. tryNodeResolve uses normalizePath
-      // which returns with '/', require.resolve returns with '\\'
-      requireEntry = normalizePath(require.resolve(id, { paths: [root] }))
     } catch (e) {
       try {
         // no main entry, but deep imports may be allowed
@@ -152,38 +138,9 @@ function collectExternals(
     else if (!esmEntry.includes('node_modules')) {
       const pkgPath = resolveFrom(`${id}/package.json`, root)
       depsToTrace.add(path.dirname(pkgPath))
-    }
-    // has separate esm/require entry, assume require entry is cjs
-    else if (esmEntry !== requireEntry) {
+    } else {
       ssrExternals.add(id)
     }
-    // if we're externalizing ESM and CJS should basically just always do it?
-    // or are there others like SystemJS / AMD that we'd need to handle?
-    // for now, we'll just leave this as is
-    else if (/\.m?js$/.test(esmEntry)) {
-      const pkgPath = resolveFrom(`${id}/package.json`, root)
-      const pkgContent = fs.readFileSync(pkgPath, 'utf-8')
-
-      if (!pkgContent) {
-        continue
-      }
-      const pkg = JSON.parse(pkgContent)
-
-      if (pkg.type === 'module' || esmEntry.endsWith('.mjs')) {
-        ssrExternals.add(id)
-        continue
-      }
-      // check if the entry is cjs
-      const content = fs.readFileSync(esmEntry, 'utf-8')
-      if (CJS_CONTENT_RE.test(content)) {
-        ssrExternals.add(id)
-        continue
-      }
-
-      logger.warn(
-        `${id} doesn't appear to be written in CJS, but also doesn't appear to be a valid ES module (i.e. it doesn't have "type": "module" or an .mjs extension for the entry point). Please contact the package author to fix.`
-      )
-    }
   }
 
   for (const depRoot of depsToTrace) {