moduleDirectories vs modulePaths

[andrewbaxter]

Documentation Is:

• Missing
• Needed
• Confusing
• Not Sure?

Please Explain in Detail...

The descriptions for the two are not meaningfully different, in addition the link to NODE_PATH doesn't work and (assuming I found the current documentation) says roughly the same thing as the other two.

I looked at the code and AFAICT moduleDirectories identifies stopping directories when trying to find the package.json for a specific json file (i.e. it stops going up looking for further directories at that point). This surprises me because it seems to have nothing to do with the current description in the documentation, but somewhat explains why / is forbidden (it would also be helpful if the error message mentioned / explicitly since "name" does not always imply a single path segment).

Having read the code, I'd guess that if you specify a/b/c as a modulePaths element, moduleDirectories should include c for the same reason it by default includes node_modules.

[eliot-akira]

I was also confused by the difference between moduleDirectories and modulePaths.

I had a working setup with @rollup/plugin-node-resolve version 14.0.1, which broke on version 14.1.0 with the following error.

Error: `moduleDirectories` option must only contain directory names. If you want to load modules from somewhere not supported by the default module resolution algorithm, see `modulePaths`.

The error message is confusing too - perhaps it should link to the docs for these two options.

Apparently modulePaths is for absolute paths (/a/b/c), and moduleDirectories is for matching single directory name (c) regardless of where it is.

[davidhellmann]

Same error here.
My config looks like this:

...
nodeResolve({
  moduleDirectories: [path.resolve('./node_modules')],
}),

works until I update to the latest version.

[stale]

Hey folks. This issue hasn't received any traction for 60 days, so we're going to close this for housekeeping. If this is still an ongoing issue, please do consider contributing a Pull Request to resolve it. Further discussion is always welcome even with the issue closed. If anything actionable is posted in the comments, we'll consider reopening it. ⓘ

[jorenbroekema]

Yeah this was quite confusing to me as well. Seems like I could just drop-in replace moduleDirectories with modulePaths, but is very unclear on what the difference is exactly and when to use what.

[jorenbroekema]

#1104 (review) here's a bit more info, I believe it was completely missed in this PR that this change was a breaking change. Users of this plugin may have relied on moduleDirectories being paths with '/'s, I certainly did, so breaking that by throwing an error and forcing users to use the new option is definitely a breaking change.