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Extenstionless main files and ES modules interaction #33223
Description
Activity
@nodejs/modules-active-members
This is intentional. See #31415. The intent is to preserve the ability for extensionless files under
"type": "module"to be non-JavaScript in the future, e.g. WASM.The workarounds are to either make a symlink (e.g.
mochawhich points tomocha.js) or to create a new"type": "commonjs"package scope and havemochabe a CommonJS file (even if all it does isimport()the ESM one). See #31415 (comment).Reacted by Jordan HarbandThe problem is that node is supposed to be treating the
./mochaentrypoint as CommonJS, not ESM. mocha's package.json does not declare"type": "module". I believe this is a mistake in the original description of this bug report.The addition of the
--loaderflag is causing node to treat the entrypoint as ESM. When--loaderis omitted, node correctly treats the entrypoint as CommonJS.To reproduce on node v14.0.0:
echo '{}' > package.json touch hooks.mjs touch foo node ./foo # <-- this works; no output; exit code 0 node --loader ./hooks.mjs ./foo # <-- this fails with an error, even though ./foo should be treated as CommonJSReacted by Eugene and Jordan HarbandI believe this is a mistake in the original description of this bug report.
Do you mind please opening a new issue for this? I think it'll get lost in this one.
What steps will reproduce the bug?
Create file
package.json:{ "type": "module" }Create file
main(no extension):Run:
node ./mainHow often does it reproduce? Is there a required condition?
Always.
What is the expected behavior?
mainfile to be executed.What do you see instead?
Additional information
This works in version 12. But does not work in versions 13 and 14.
--experimental-specifier-resolution=nodeflag does not help.Real world example: we have mocha (which main entry file is extensionless), we have ts-node esm-loader, now we want to test ts files with native es modules, like that:
node --loader ts-node/esm.mjs node_modules/mocha/bin/mocha --extension tsbut we get the error described above. But if we rename
node_modules/mocha/bin/mochatonode_modules/mocha/bin/mocha.js, then everything works as expected.