default export from svelte-kit package

[janosh]

How do I create a default export in a svelte-kit package? Would be cool if the docs included some guidance on that. If I add an index file that re-exports a Svelte component as default,

// src/lib/index.js
export { default } from './MyComponent.svelte'

and then install the package and try

import MyComponent from 'my-package'

I get

Must use import to load ES Module: my-package/index.js
require() of ES modules is not supported.
require() of my-package/index.js from repo/node_modules/vite/dist/node/chunks/dep-0ed4fbc0.js is an ES module file as it is a .js file whose nearest parent package.json contains "type": "module" which defines all .js files in that package scope as ES modules.
Instead rename index.js to end in .cjs, change the requiring code to use import(), or remove "type": "module" from my-package/package.json.

The easiest solution to this in the past was to use the "svelte" field in package.json but sveltekit package does not copy that field into its output.

I asked this question here as well.

[ignatiusmb]

There's nothing wrong with your export code, it's still a vite problem that can't properly handle it, #1148 patches it by forcing packages with "svelte" to be bundled in ssr.noExternal. Since library published with svelte-kit package have a predefined package keys, there's no other way to fix it (currently) other than manually adding "svelte": "index.js" after packaging, or your library name to ssr.noExternal in the svelte config file.

#1735 would solve this as it will preserve the original package.json as is, so you can write "svelte" key yourself and point it to any file you want.

[janosh]

@ignatiusmb Thanks, that was helpful! Which vite issue is the one that tracks correctly handling (Svelte?) exports?