fix: esbuild code split

[screetBloom]

Version

4.14.0

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update
• Refactor
• Docs
• Underlying tools
• Other, please describe:

Questions

code splitting in esbuild must be esm. see here 👉 esbuild-splitting

When we encounter problems with __require.resolve we can solve them with esbuild --format=cjs

But in tsup we can't do that, we have to tsup --format cjs --no-splitting

I looked at the source code, and find:

1. tsup defaults to cjs, tsup-src/index.js-355
2. By default. --no-splitting will be undedined, So that always options.splitting !== false
3. Then splitting && format === 'cjs' ? 'esm' : format will be esm

Related bugs

• bug: tsup#369

Steps to reproduce

tsup-mini-repo

This is also the first pr I mentioned to tsup. If can merged I will be very happy. And very much open to feedback on this PR if you have suggestions for improvements.

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[screetBloom]

@egoist
When have time you can check this pr, I would like to get some feedback💡

[egoist]

When we encounter problems with __require.resolve we can solve them with esbuild --format=cjs

But in tsup we can't do that, we have to tsup --format cjs --no-splitting

This is expected in v4, we achieved code splitting for cjs by bundling the code in esm format and then convert to cjs format, see https://tsup.egoist.sh/#why-does-export--get-transpiled-to-module-exports-default

But it seems this has been causing a lot of issues, so I may disable code splitting for cjs format in v5. #317

[github-actions]

🎉 This PR is included in version 5.0.0 🎉

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