feat(check:policy): Prevent .js file extension #19106
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| /** | ||
| * A policy handler that checks for JavaScript source files that just use the .js file extension. Such files may be | ||
| * interpreted by node as either CommonJS or ESM based on the `type` field in the nearest package.json file. However | ||
| * this is not deterministic. Using file extensions reduces ambiguity and makes the behavior deterministic. |
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What is not deterministic? You just mean that we might change the package type?
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I mean that you can break things that are seemingly unrelated by adding type: module to a package. It's not obvious that adding a field to a package.json would cause an unrelated config file like .eslintrc.js to stop being interpreted correctly.
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Doesn't seem not related. That is the system.
Brings to mind the missing fluid build dependency on package.json. Change package.json as you like. Build cache doesn't care.
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Clarified the comment. I understand that this is node's behavior, but it is not obvious, and it's also new(ish).
build-tools/packages/build-tools/src/repoPolicyCheck/handlers/noJsFiles.ts
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build-tools/packages/build-tools/src/repoPolicyCheck/handlers/noJsFiles.ts
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Adds a policy handler that checks for JavaScript source files that just use the .js file extension. Such files may be interpreted by node as either CommonJS or ESM based on the `type` field in the nearest package.json file. However, this is can lead to confusing behavior when updating packages to use `type`. Using explicit file extensions reduces ambiguity and ensures a CJS file isn't suddenly treated like an ESM file.
Adds a policy handler that checks for JavaScript source files that just use the .js file extension. Such files may be interpreted by node as either CommonJS or ESM based on the
typefield in the nearest package.json file. However, this is can lead to confusing behavior when updating packages to usetype. Using explicit file extensions reduces ambiguity and ensures a CJS file isn't suddenly treated like an ESM file.