Core: Fix false-positive CJS warning when 'exports' appears in strings or comments

[reeseo3o]

Closes #33507

What I did

Fixed a false-positive CommonJS (CJS) deprecation warning that was incorrectly triggered when the word exports appeared inside string literals or comments, even in projects fully using ESM.

This PR adds a small preprocessing step to strip string literals and comments from the source code before applying the existing CJS detection regex in build-dev.ts.

As a result, the warning is now triggered only by actual CommonJS syntax (e.g. module.exports, exports.foo, require()), and not by file names, import paths, or comments.

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

Added unit tests (Vitest) for stripCommentsAndStrings to verify that
string literals and comments are removed while preserving actual CJS syntax.

Manual testing

Caution

This section is mandatory for all contributions. If you believe no manual test is necessary, please state so explicitly. Thanks!

Manual verification steps

1. Used an existing Vite-based Storybook project configured with ESM.
2. Added an import path containing exports, for example:

import { foo } from './drei-exports.ts';

3. Added comments and string literals containing exports, for example:

// missing components/exports
const file = 'exports.ts';

4. Ran Storybook and confirmed that no CommonJS deprecation warning was shown.
5. Added actual CommonJS syntax (e.g. module.exports = {}) and confirmed that the warning is still triggered.

Summary by CodeRabbit

Release Notes

• Bug Fixes

  • Improved CommonJS deprecation warning accuracy by filtering out comments and strings before pattern detection, preventing false positives.

• Tests

  • Added comprehensive test suite for comment and string stripping functionality, covering single/double quotes, template literals, and block/line comments.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

📝 Walkthrough

Walkthrough

A new utility function stripCommentsAndStrings is introduced to remove comments and string literals from JavaScript code, with comprehensive tests validating its behavior across various scenarios. The function is then integrated into the build-dev process to normalize content before evaluating CommonJS deprecation warnings.

Changes

Cohort / File(s)	Summary
New Utility Function code/core/src/core-server/utils/strip-comments-and-strings.ts	Adds exported function that strips string literals (single, double, backtick quotes) and comments (block and line) from code via sequential regex/string replacements.
Utility Tests code/core/src/core-server/utils/strip-comments-and-strings.test.ts	New test suite validating string removal (all quote styles and template literals), line comment stripping, block comment stripping, and preservation of unaffected code.
Build Integration code/core/src/core-server/build-dev.ts	Imports and applies stripCommentsAndStrings to preprocess mainJsContent before running CommonJS pattern regex test, changing control flow to normalize content first.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

✨ Finishing touches

• 📝 Generate docstrings

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[storybook-app-bot]

Package Benchmarks

^{Commit: 7bb50d1, ran on 28 January 2026 at 08:01:43 UTC}

The following packages have significant changes to their size or dependencies:

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