From 23c05dd19bf0f2d4dfab7dc26ed92819d562ebcb Mon Sep 17 00:00:00 2001
From: Michael Shilman <shilman@users.noreply.github.com>
Date: Fri, 11 Feb 2022 12:09:48 +0800
Subject: [PATCH] Revert "Revert "Core: Rename `generated-stories-entry` to
 `cjs` extension so require works""

---
 lib/builder-webpack5/src/preview/iframe-webpack.config.ts | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/lib/builder-webpack5/src/preview/iframe-webpack.config.ts b/lib/builder-webpack5/src/preview/iframe-webpack.config.ts
index 21e1dc9cf503..7ee55f9f1800 100644
--- a/lib/builder-webpack5/src/preview/iframe-webpack.config.ts
+++ b/lib/builder-webpack5/src/preview/iframe-webpack.config.ts
@@ -128,6 +128,8 @@ export default async (options: Options & Record<string, any>): Promise<Configura
       const clientApi = storybookPaths['@storybook/client-api'];
       const clientLogger = storybookPaths['@storybook/client-logger'];
 
+      // NOTE: although this file is also from the `dist/cjs` directory, it is actually a ESM
+      // file, see https://github.com/storybookjs/storybook/pull/16727#issuecomment-986485173
       virtualModuleMapping[`${configFilename}-generated-config-entry.js`] = interpolate(
         entryTemplate,
         {
@@ -142,7 +144,10 @@ export default async (options: Options & Record<string, any>): Promise<Configura
       const storyTemplate = await readTemplate(
         path.join(__dirname, 'virtualModuleStory.template.js')
       );
-      const storiesFilename = path.resolve(path.join(workingDir, `generated-stories-entry.js`));
+      // NOTE: this file has a `.cjs` extension as it is a CJS file (from `dist/cjs`) and runs
+      // in the user's webpack mode, which may be strict about the use of require/import.
+      // See https://github.com/storybookjs/storybook/issues/14877
+      const storiesFilename = path.resolve(path.join(workingDir, `generated-stories-entry.cjs`));
       virtualModuleMapping[storiesFilename] = interpolate(storyTemplate, { frameworkImportPath })
         // Make sure we also replace quotes for this one
         .replace("'{{stories}}'", stories.map(toRequireContextString).join(','));