EntryPointError: libp2p fails to build - exports map support missing?

[achingbrain]

The libp2p module does not include a main field in it's package.json, instead it uses an export map with a "." property which is the default package entry point.

When trying to look at bundle sizes for this module I see EntryPointError: We could not guess a valid entry point for this package. - does bundlephobia understand export maps or does it only support the "main" field?

[donmccurdy]

I'm interested in this question too. I noticed the @sindresorhus/safe-stringify package is fine on bundlephobia, specifying:

	"type": "module",
	"exports": "./index.js",

https://github.com/sindresorhus/safe-stringify/blob/b1278c4c45c09a6cd888e0b94dab989ea559a941/package.json#L13-L14

But my own package fails:

  "type": "module",
  "sideEffects": false,
  "exports": "./dist/ktx-parse.modern.js",
  "types": "./dist/index.d.ts",

https://github.com/donmccurdy/KTX-Parse/blob/639716009a382c892dfdf906357b61dd271973f6/package.json#L5-L9

[owenallenaz]

I booted it up locally and messed around with it, and it looks like the root culprit is two issues.

• If the package contains an "index.js" file it uses it, regardless of what is in the exports key.
• If the package doesn't contain an index.js, as yours doesn't, and mine as well, then it just bombs. This is due to webpack version 4 in the loader system. I attempted to update it in a PR, but is really messy because it requires updating a bunch of the loaders and a really complex webpack config file. I think there's a chance if webpack was updated and the breaking changes from webpack v4 to webpack v5 were resolved the solution would "just work" like magic.

pastelsky/package-build-stats@master...owenallenaz:package-build-stats:v5-attempt . Unfortunately the webpack changes are a bit out of my depth with the intent of the package and it's internals...

[achingbrain]

For those still hitting this problem, I started using https://packagephobia.com instead, it supports modern packaging conventions so works with exports maps.