package.json exports resolution uses fallback conditions, unlike Node (original) (raw)

Bug Report

🔎 Search Terms

I’ve never been more confident, without searching, that I’m the first person to notice this

💻 Code

{ "exports": { ".": { "import": "./dist/main.mjs", "types": "./dist/foo.d.ts" } } }

🙁 Actual behavior

Importing this package from an ESM file, in --moduleResolution nodenext, searches for types at these locations:

• ./dist/main.mts
• ./dist/main.d.mts
• ./dist/foo.d.ts

🙂 Expected behavior

It should not search the types condition, because import already matched, and contained a valid target ./dist/main.mjs. Resolution here should fail for consistency with Node, which would throw a resolution error if it matched a condition but then failed to find the file specified in it.

Fixing this bug may cause more harm than good. I noticed it because I claimed that a popular library would be broken under certain conditions due to misconfigured exports, but was proven wrong in reality. I figured this may be worth documenting, but likely not worth fixing. But if someone can make a good case for why it matters, I would reconsider.