Baseline Widely available *
Note: This feature is available in Web Workers.
The cache
read-only property of the Request
interface contains the cache mode of the request. It controls how the request will interact with the browser's HTTP cache.
A RequestCache
value. The available values are:
default
â The browser looks for a matching request in its HTTP cache.
no-store
â The browser fetches the resource from the remote server without first looking in the cache, and will not update the cache with the downloaded resource.
reload
â The browser fetches the resource from the remote server without first looking in the cache, but then will update the cache with the downloaded resource.
no-cache
â The browser looks for a matching request in its HTTP cache.
force-cache
â The browser looks for a matching request in its HTTP cache.
only-if-cached
â The browser looks for a matching request in its HTTP cache. Experimental
The "only-if-cached"
mode can only be used if the request's mode
is "same-origin"
. Cached redirects will be followed if the request's redirect
property is "follow"
and the redirects do not violate the "same-origin"
mode.
// Download a resource with cache busting, to bypass the cache
// completely.
fetch("some.json", { cache: "no-store" }).then((response) => {
/* consume the response */
});
// Download a resource with cache busting, but update the HTTP
// cache with the downloaded resource.
fetch("some.json", { cache: "reload" }).then((response) => {
/* consume the response */
});
// Download a resource with cache busting when dealing with a
// properly configured server that will send the correct ETag
// and Date headers and properly handle If-Modified-Since and
// If-None-Match request headers, therefore we can rely on the
// validation to guarantee a fresh response.
fetch("some.json", { cache: "no-cache" }).then((response) => {
/* consume the response */
});
// Download a resource with economics in mind! Prefer a cached
// albeit stale response to conserve as much bandwidth as possible.
fetch("some.json", { cache: "force-cache" }).then((response) => {
/* consume the response */
});
// Naive stale-while-revalidate client-level implementation.
// Prefer a cached albeit stale response; but update if it's too old.
// AbortController and signal to allow better memory cleaning.
// In reality; this would be a function that takes a path and a
// reference to the controller since it would need to change the value
let controller = new AbortController();
fetch("some.json", {
cache: "only-if-cached",
mode: "same-origin",
signal: controller.signal,
})
.catch((e) =>
e instanceof TypeError && e.message === "Failed to fetch"
? { status: 504 } // Workaround for chrome; which fails with a TypeError
: Promise.reject(e),
)
.then((res) => {
if (res.status === 504) {
controller.abort();
controller = new AbortController();
return fetch("some.json", {
cache: "force-cache",
mode: "same-origin",
signal: controller.signal,
});
}
const date = res.headers.get("date"),
dt = date ? new Date(date).getTime() : 0;
if (dt < Date.now() - 86_400_000) {
// if older than 24 hours
controller.abort();
controller = new AbortController();
return fetch("some.json", {
cache: "reload",
mode: "same-origin",
signal: controller.signal,
});
}
// Other possible conditions
if (dt < Date.now() - 300_000)
// If it's older than 5 minutes
fetch("some.json", { cache: "no-cache", mode: "same-origin" }); // no cancellation or return value.
return res;
})
.then((response) => {
/* consume the (possibly stale) response */
})
.catch((error) => {
/* Can be an AbortError/DOMException or a TypeError */
});
Specifications Browser compatibility See also
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4