Post

wouldn't it be nice if sites could share a cache of common js? ... stuff like react, or vue or svelte? 👉 there's an early stage proposal for cross-origin storage which enables exactly this. there are challenges but I think it's very interesting indeed

We used to have this many years ago by default. It was common to load jQuery et al from a public CDN so most people wouldn't have to download it again just for your site. Then marketers started using it to fingerprint. And hackers used it to poison cross-origin JS. The feature got removed sigh

Due to the way caches are domain sharded for privacy, it doesn’t really work that well. Caches aren’t as effective as people had hoped. That, and a third party takeover of a CDN is too bigger security risk for most websites

Being hash-based helps us there. You can be sure about the content as long as the hash matches. A resource with hash abc123 put in the COS cache can be trusted, even if it came from sketchy-server dot com. The hash is checked before writing to COS.

As an aside, we adopted SSRI for @calibreapp.com RUM and it’s a really great assurance to have as a script provider.