NavigationPreloadManager: setHeaderValue() method
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since April 2022.
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 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
InvalidStateErrorDOMException-
There is no active worker associated with the registration to which this
NavigationPreloadManagerbelongs.
Examples
The code below demonstrates how the value might be set.
navigator.serviceWorker.ready
.then((registration) =>
registration.navigationPreload.setHeaderValue(newValue),
)
.then(() => console.log("Done!"))
.catch((e) =>
console.error(`NavigationPreloadManager not supported: ${e.message}`),
);
Specifications
| Specification |
|---|
| Service Workers # dom-navigationpreloadmanager-setheadervalue |
Browser compatibility
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