NavigationPreloadManager.setHeaderValue()
The setHeaderValue()
method of the NavigationPreloadManager
interface sets the value of the Service-Worker-Navigation-Preload
header that will be sent with requests resulting from a fetch()
operation made during service worker navigation preloading.
It returns an empty Promise
that resolves with undefined
.
The presence of the Service-Worker-Navigation-Preload
header in preloading requests allows servers to configure the returned resource differently for preloading fetch requests than from normal fetch requests.
The default directive is set to true
: this method allows the possibility of configuring multiple different responses to preload requests.
Note: If a different response may result from setting this header, the server must set Vary: Service-Worker-Navigation-Preload
to ensure that the different responses are cached.
Syntax
setHeaderValue(value)
Parameters
value
-
An arbitrary string value, which the target server uses to determine what should returned for the requested resource.
Return Value
Exceptions
InvalidStateError
DOMException
-
There is no active worker associated with the registration to which this
NavigationPreloadManager
belongs.
Examples
The code below demonstrates how the value might be set.
navigator.serviceWorker.ready
.then((registration) => {
return registration.navigationPreload.setHeaderValue(newValue);
})
.then(() => {
console.log("Done!");
})
.catch(e => console.error("NavigationPreloadManager not supported: " + e.message));
Specifications
No specification found
No specification data found for api.NavigationPreloadManager.setHeaderValue
.
Check for problems with this page or contribute a missing spec_url
to mdn/browser-compat-data. Also make sure the specification is included in w3c/browser-specs.
Browser compatibility
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