warning with rollup-plugin-svelte

[saiballo]

If I use just-debounce-it with rollup I receive this warning:

[rollup-plugin-svelte] The following packages did not export their package.json file so we could not check the "svelte" field. If you had difficulties importing svelte components from a package, then please contact the author and ask them to export the package.json file.

[saibotsivad]

Summarized Discussions

Reading through the discussion at rollup-plugin-svelte#181, probably the most pertinent information comes from the NodeJS docs:

Warning: Introducing the "exports" field prevents consumers of a package from using any entry points that are not defined, including the package.json (e.g. require('your-package/package.json'). This will likely be a breaking change.
https://nodejs.org/api/packages.html#packages_package_entry_points

And in a discussion on a different repo PR, a comment points out:

[...] it's about the "package.json" not being accessible to the outside world. Doesn't matter who or what is trying to read the package.json file, anything outside of this module's own files can't look at the file cuz it's not defined as an export.

This is very standard & has been part of the ESM resolution algorithm and official documentation + example since very early days.

Where was it introduced in just?

So for example, in just-kebab-case the package.json has the exports property which looks like this:

  "exports": {
    ".": {
      "require": "./index.js",
      "default": "./index.mjs"
    }
  },

It looks like all these were introduced in #315 "enable esm", which was a big refactor and update.

What's the solution?

The "enable esm" change was not recorded as a breaking change, see conversation, however the NodeJS docs say

Introducing the "exports" field [...] will likely be a breaking change.

and indeed it is a breaking change for projects that want to import the package.json file, so it seems like a bug-fix patch is in order to add the package.json file to the exports.

That would look like this:

  "exports": {
    ".": {
      "require": "./index.js",
      "default": "./index.mjs"
    },
    "./package.json": "./package.json"
  },

Unfortunately, this would need to be done to all the packages.

[saibotsivad]

@angus-c if you'd like a pull request for the above solution, I can put one together that "just" (tee-hee!) runs that diff for all appropriate package.json files.

[angus-c]

That would be great. Thanks!

[saibotsivad]

I got you fam, see PR #484 🎉