Allow vite to split dynamic imports to multiple files

[arbassett]

related #739

by not allowing vite to split dynamic imports rollup is unable to do any dead code elimination... with the current setup vite will always include dynamic imports even if they are never available like clientOnly in ssr. also vite's default output in esm so setting it to esm its redundant

How does this effect adapters?

• For adapters that use file output nothing is changed it will still output a single file
• For adapters that use dir output rollup will dump the extra files in the output folder which is just dist in all cases currently and from my testing the frameworks had no issue picking up the extra files.

to confirm that client only is removed i have a example repo here https://github.com/arbassett/solid-start-clientOnly-fix with the patch and committed dist dir to show that the clientOnly import was removed from the server build

[ryansolid]

I really want to look back at why we added this. It feels like it was for a reason. But I'm glad you found the problem. I'm pretty sure routing removes dynamic imports on server anyway so it probably isn't that. It looks like the adapters pass so it isn't that either. There are some consequences for synchronous SSR will dynamic imports but it probably doesn't matter enough.

[arbassett]

I'm not familiar with how solid routers internals work but from the bundler perspective having two files and one file doesn't change the end result being a Promise based import

without patch

const Lazy$2 = lazy(() => Promise.resolve().then(() => Lazy$1));

with Patch

const Lazy = lazy(() => import('./Lazy.b41f2dd3-bba4a033.js'));

hopefully this info helps your decision

[ryansolid]

With the router we just remove the lazy on the server. We didn't always. The other reason I could have seen was like quick solve for bundling for old Cloudflare stuff.. But like everything passes here so it is probably fine now. Some legacy thing long forgotten.