preact-cli: All routes are chunked, causing hydration of prerendered pages to flicker

It appears that all routes are being chunked and async loaded, even without the presence of the async! prefix.

I’ve reproduced this using preact-cli 1.4.1 here: https://github.com/ajoslin/preact-cli-issue-all-routes-chunked. Just build and serve and check the network tab, it loads both bundle and route-home.chunk. And it does a render before the home chunk is loaded.

Details

I have a prerendered homepage. Here’s the process when the user visits the site:

1. Index.html loads with prerendered content
2. Main JS bundle loads
   • Initial render is triggered without the home component downloaded
   • Bundle begins downloading route-home.chunk.js
3. Wait for route-home.chunk.js is loaded
4. Home route chunk loads and the home content renders

Between (2) and (4), a version of the app is rendered that does not include the home route’s content, because the home route’s JS is still loading.

This results in a noticeable “flicker” of the home content being removed then re-appearing as soon as the initial bundle loads.

I’m not using the async! prefix when importing my home route, but it looks like the home route is being chunked anyway.