Frontend & browser·Modules, bundling and the build
the JavaScript is cached for a year because its name guarantees the contents can never change.
Immutable caching
Also calledCache-Control immutable, long-term caching
Serving hashed assets with a very long max-age and the `immutable` directive, so the browser does not even revalidate them. It is the payoff for content hashing and the single biggest win for repeat visits. It is also unforgiving: an unhashed file served this way is stuck in caches you do not control until the max-age expires.