rollupjs avoid duplicated functions with multi files - rollup

Question

I'm trying to pack all the common libraries to be used with multiple projects without an actual entry files. Thus I need all the functions to be included in the bundle
Thus I'm trying to achieve that using #rollup/plugin-multi-entry pointing to all the files inside the directory
The problem I'm facing currently is that, some of the files extends each other, when packed, the extended function is duplicated multiple times with the name $n and so on, is it possible to make rollup not duplicate those extended functions?
Thanks

Answer 1

Bundling libraries inside a vendor file is now considered an anti-pattern since you will neglect the benefits of three-shaking. It will also come with worse caching since every time some lib changes the cache of the whole vendor will be invalidated and, finally, you won't benefit from http2 multiplexing that much.
If you still want to do it, in order to give them reliable names (and avoid naming conflicts) it is much easier to do it manually:
// vendor.js
import * as lib1 from 'lib1';
import * as lib2 from 'lib2';
export {lib1, lib2}
The previous module, when used as entry point, will result in exporting all exports from both libraries under its respective namespaces, and rollup will internally handle dependencies between libs correctly.
Edit: if you can bundle the libraries along with the project and not in a different process you can do it like so:
// rollup.config.js
const libs = ['lib1', 'lib2'];
{
input: 'index.js',
manualChunks: {
vendor: libs.map((lib) => require.resolve(lib))
},
// ...
}