docs/middleware/cache-control.js

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1.7 KiB
JavaScript

// Return a function you can pass a Response object to and it will
// set the `Cache-Control` header.
//
// For example:
//
// const cacheControlYear = getCacheControl(60 * 60 * 24 * 365)
// ...
// cacheControlYear(res)
// res.send(body)
//
// Or, if you want to make it definitely not cache:
//
// const noCacheControl = getCacheControl(0) // you can use `false` too
// ...
// noControlYear(res)
// res.send(body)
//
// Max age is in seconds
export function cacheControlFactory(
maxAge = 60 * 60,
{ key = 'cache-control', public_ = true, immutable = false } = {}
) {
const directives = [
maxAge && public_ && 'public',
maxAge && `max-age=${maxAge}`,
maxAge && immutable && 'immutable',
!maxAge && 'private',
!maxAge && 'no-store',
]
.filter(Boolean)
.join(', ')
return (res) => {
if (process.env.NODE_ENV !== 'production' && res.hasHeader('set-cookie')) {
console.warn(
"You can't set a >0 cache-control header AND set-cookie or else the CDN will never respect the cache-control."
)
}
res.set(key, directives)
}
}
// 24 hours for CDN, we soft-purge this with each deploy
const defaultCDNCacheControl = cacheControlFactory(60 * 60 * 24, {
key: 'surrogate-control',
})
// Shorter because between deployments and their (sort) purges,
// we don't want the browser to overly cache because with them we
// can't control purging.
const defaultBrowserCacheControl = cacheControlFactory(60)
// A general default configuration that is useful to almost all responses
// that can be cached.
export function defaultCacheControl(res) {
defaultCDNCacheControl(res)
defaultBrowserCacheControl(res)
}