Make vite.config.ts support pure esm modules without setting type: "module"

[egoist]

Clear and concise description of the problem

In a cjs project (i.e. without type: 'module' in package.json), if you import a package written in pure esm in vite.config.ts, it will panic:

 Error [ERR_REQUIRE_ESM]: require() of ES Module

Since Vite will bundle vite.config.ts in cjs format.

Suggested solution

Switching to https://github.com/egoist/bundle-require:

It outputs the bundled config as .mjs with a random filename (to get rid of import cache) and loaded with dynamic import by default.

// Not sure if this would break existing behavior tho.

Alternative

Just adding type: 'module' to your package.json would also fix this.

Additional context

No response

Validations

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[sodatea]

Alternative: support vite.config.mts.

[Akryum]

Reposting the minimal repro here:
https://github.com/Akryum/vite-config-esm-issue

[bluwy]

vite.config.mts supported has landed in #8729. Given the thumbs-up for the alternative I'll go ahead and close this as resolved.

Though I think using bundle-require could potentially still be something we can explore if someone's interested in implementing it.