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.

[NexxLuo]

Set externals can't auto import async module , must load the script manually with additional code .
I have implemented it the following configuration :

rspack: {
      optimization: {
        splitChunks: {
          chunks: 'async', 
          cacheGroups: {
            vendor: {
              test: /[\\/]node_modules[\\/]/,
              name: 'vendor',
              chunks: 'async'
            }
          }
        },
      },
      output: {
        asyncChunks: true,
        chunkFilename: '[name].chunk.js',
      }
    }