How to create an async chunk when buliding umd package?

[NexxLuo]

There are some large npm package , eg : pdfjs、xlsx .
I import then by using import() , but them always bundle into an one umd file.
How to build them into runtime async chunk ?
Of course i know externals can ignore bundle , but can`t auto dynamic import when runtime .

[Timeless0911]

Maybe you can set tools.rspack.output.asyncChunks: true to enable async chunks.

BTW, I think use dynamic import with externals is enough. I've never done split chunks with UMD format, so I can't be of much help. If you've successfully configured UMD split chunks with webpack or Rspack, you can directly transfer your configuration here via tools.rspack.