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 AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung Internet
Basic support
Experimental
Chrome Full support 59Edge ? Firefox ? IE ? Opera Full support 46Safari ? WebView Android Full support 59Chrome Android Full support 59Edge Mobile ? Firefox Android ? Opera Android Full support 46Safari iOS ? Samsung Internet Android Full support 7.0

Legend

Full support  
Full support
Compatibility unknown  
Compatibility unknown
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.

Document Tags and Contributors

Contributors to this page: fscholz, jpmedley
Last updated by: fscholz,