fix: CJS detection regression for packages with "export" in comments#3793
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bartlomieju merged 2 commits intomainfrom Apr 28, 2026
Merged
fix: CJS detection regression for packages with "export" in comments#3793bartlomieju merged 2 commits intomainfrom
bartlomieju merged 2 commits intomainfrom
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The content-based heuristic (`code.includes("export ")`) was fooled by
CJS files containing the word "export" in comments — e.g.
`@opentelemetry/api`'s CJS entry has a comment:
// TODO: Remove ProxyTracerProvider export in the next major version.
This caused the CJS shim to be skipped, leaving `exports` undefined
when Vite's ESModulesEvaluator ran the file.
Replace the naive string check with two-layer detection:
1. Package.json "type" field (Node.js semantics): .cjs is always CJS,
.js is CJS unless the nearest package.json has "type": "module".
Results are cached per directory.
2. ESM statement regex fallback: for dual CJS/ESM packages that ship
ESM in .js without "type": "module" (e.g. @opentelemetry/api),
detect actual ESM syntax (export/import statements) including
minified forms like `import{` and `export*from`.
Also adds a test that imports from a real CJS npm package (qs) in
node_modules, since the existing CJS test fixtures were local ESM
files that never exercised the shim path.
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## Summary - Bump `@fresh/core` 2.3.1 → 2.3.2 - Bump `@fresh/plugin-vite` 1.1.0 → 1.1.1 - Bump `@fresh/init` 2.3.1 → 2.3.2 - Bump `@fresh/update` 2.3.1 → 2.3.2 Patch release for the CJS detection regression fix (#3793).
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bartlomieju
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## Summary Reverts two commits that broke CJS package handling in dev mode: - Reverts #3793 (CJS detection regex fix) - Reverts #3767 (removal of Babel CJS→ESM transform) The simplified CJS shim introduced in #3767 has two fundamental issues: 1. **Detection**: the heuristic (`code.includes("export ")`) is fooled by comments containing "export" 2. **Named exports**: the shim only provides `export default module.exports`, so `import { trace } from "@opentelemetry/api"` returns `undefined` (#3797) The Babel-based transform handled both correctly. Bringing it back until we can replace it with a proper solution using `deno_ast`'s CJS parser.
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Closes #3794
Fixes a regression from #3767 where CJS npm packages fail with
exports is not definedin dev mode.code.includes("export ")) was fooled by the word "export" appearing in comments of CJS files — e.g.@opentelemetry/apihas// TODO: Remove ProxyTracerProvider export in the next major version.which caused the CJS shim to be skipped entirelytypefield (Node.js semantics):.cjs→ always CJS,.js→ CJS unless nearestpackage.jsonhas"type": "module". Results cached per directory..jswithout"type": "module"(e.g.@opentelemetry/api,preact-render-to-string), detects actual ESM syntax including minified forms likeimport{andexport*fromqs) innode_modules— the existing "CJS test" fixtures were local ESM files that never exercised the shim path