Service-Worker-Navigation-Preload request header indicates that the request was the result of a
fetch() operation made during service worker navigation preloading.
It allows a server to respond with a different resource than for a normal
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.
The header below is sent by default.
The service worker can set a different header value using
For example, in order to request that a fragment of the requested resource be returned in JSON format, the value could be set with the string
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