Problem

When Dioxus fullstack serves resources like the app.wasm and web.js files, these are not properly cached by the browser or any intermediate CDNs like CloudFlare.

Expected behavior

All immutable resources should be served with proper cache control headers and with unique hashed names to enable most efficient caching.

How to improve

Here's a network snapshot of a second load of a Dioxus web app.

Even though none of the resources are actually downloaded (beyond the initial index.html), it still takes over 500ms for the page to properly load. This is due to browser issuing requests for all resources with if-modified-since: Tue, 03 Dec 2024 17:49:30 GMT header, to which the server promptly responses 304 Not Modified. But due to network latency, this takes 136ms.

Having an intermediate cache like CloudFlare would not help, since it would also need to check with the origin server if the resource has changed.

Solution involves two things:

1. Encode a content hash to resource file names to make them unique (instead of web_bg.wasm use web_bg_12398718923.wasm)
2. Provide proper cache control headers indicating immutability and a very long max age

Third thing is to bundle up all the JS files into a single JS file as suggested in #3277

Example header

Cache-Control: public,max-age=31536000,immutable

This same strategy should also be extended to all public application assets coming through Manganis. But not to any (user) private assets, but these would probably not be managed with Manganis in the first place.

See also https://engineering.fb.com/2017/01/26/web/this-browser-tweak-saved-60-of-requests-to-facebook/