FetchEvent.navigationPreload

This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The navigationPreload read-only property of the FetchEvent interface returns a Promise that resolves to the instance of NavigationPreloadManager associated with the current service worker registration.

Syntax

var promise = fetchEvent.navigationPreload

Value

A Promise that resolves to the instance of NavigationPreloadManager.

Example

The following example shows the implementation of a fetch event that uses a preloaded response. 

addEventListener('fetch', event => {
  event.respondWith(async function() {
    // Respond from the cache if we can
    const cachedResponse = await caches.match(event.request);
    if (cachedResponse) return cachedResponse;

    // Else, use the preloaded response, if it's there
    const response = await event.preloadResponse;
    if (response) return response;

    // Else try the network.
    return fetch(event.request);
  }());
});

Specifications

Specification Status Comment
Service Workers
The definition of 'navigationPreload' in that specification.
Working Draft Initial definition.

Browser Compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
navigationPreload
Experimental
Chrome Full support 59Edge ? Firefox ? IE No support NoOpera Full support 46Safari No support NoWebView Android Full support 59Chrome Android Full support 59Firefox Android ? Opera Android Full support 43Safari iOS No support NoSamsung Internet Android Full support 7.0

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.