Cache: put() method
Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
Note: This feature is available in Web Workers.
The put()
method of the
Cache
interface allows key/value pairs to be added to the current
Cache
object.
Often, you will just want to fetch()
one or more requests, then add the result straight to your cache. In such cases you are
better off using
Cache.add()
/Cache.addAll()
, as
they are shorthand functions for one or more of these operations.
fetch(url).then((response) => {
if (!response.ok) {
throw new TypeError("Bad response status");
}
return cache.put(url, response);
});
Note: put()
will overwrite any key/value pair
previously stored in the cache that matches the request.
Note: Cache.add
/Cache.addAll
do not
cache responses with Response.status
values that are not in the 200
range, whereas Cache.put
lets you store any request/response pair. As a
result, Cache.add
/Cache.addAll
can't be used to store
opaque responses, whereas Cache.put
can.
Syntax
put(request, response)
Parameters
Return value
A Promise
that resolves with undefined
.
Exceptions
TypeError
-
Returned if the URL scheme is not
http
orhttps
.
Examples
This example is from the MDN simple-service-worker example (see simple-service-worker running live).
Here we wait for a FetchEvent
to fire. We construct a custom response
like so:
- Check whether a match for the request is found in the
CacheStorage
usingCacheStorage.match()
. If so, serve that. - If not, open the
v1
cache usingopen()
, put the default network request in the cache usingCache.put()
and return a clone of the default network request usingreturn response.clone()
. Clone is needed becauseput()
consumes the response body. - If this fails (e.g., because the network is down), return a fallback response.
let response;
const cachedResponse = caches
.match(event.request)
.then((r) => (r !== undefined ? r : fetch(event.request)))
.then((r) => {
response = r;
caches.open("v1").then((cache) => {
cache.put(event.request, response);
});
return response.clone();
})
.catch(() => caches.match("/gallery/myLittleVader.jpg"));
Specifications
Specification |
---|
Service Workers # cache-put |
Browser compatibility
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