esnext builds are deoptimized by empty types.js files #2896
Description
Issue summary
webpack flags any file without an import/export statement as a CommonJS module. CommonJS modules cannot be concatenated, which causes them to be wrapped in webpack boilerplate. This increases asses sizes.
Polaris 4.17.0 ships with multiple empty types.js files (e.g., features). For consumers without sewing-kit's workaround, these add a little bit of bulk :(
But types.js files existed before this!
Yeah, but:
- Some index files don't export their types
- Some types files contain non-const enums (which generate exportable code)
Probably other stuff; I haven't looked at this in depth.
But only sewing-kit consumers should be using the esnext build!
Even if that's true, these modules are causing another breakage for all sewing-kit consumers.
Expected behavior
All of Polaris to be treated as es modules.
Actual behavior
Some CommonJS boilerplate 😭
Note: I haven't verified this because all of my consumers use sewing-kit, but I'm usually right about this sort of thing 🤷♀
Steps to reproduce the problem
That's pretty involved! If you need help with that, I can cook something up for sure.