Web Periodic Background Synchronization API

Secure context
This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

Draft
This page is not complete.

The Web Periodic Background Synchronization API provides a way to register tasks to be run in a service worker at periodic intervals with network connectivity. These tasks are referred to as periodic background sync requests.

Web Periodic Background Synchronization Concepts and Usage

The Periodic Background Sync API allows web applications to alert their service worker to make any updates, at a periodic time interval. Uses may include fetching latest content whilst a device is connected to wifi, or allowing background updates to an application.

The minimum time interval is set when the API is invoked; however the user agent might also take into account other factors which affect when the service worker receives the event. For instance previous website engagement, or connection to a known network.

The PeriodicSyncManager interface is available through ServiceWorkerRegistration.periodicSync. A unique tag identifier is set to 'name' the sync event, which can then be listened for within the ServiceWorker script. Once the event is received you can then run any functionality available, such as updating caches or fetching new resources.

As this API relies on service workers, functionality provided by this API is only available in a secure context.

At the time of writing, the Web Periodic Background Synchronization API is only available through an installed Progressive Web App

Web Periodic Background Synchronization Interfaces

PeriodicSyncManager
Registers tasks to be run in a service worker at periodic intervals with network connectivity. These tasks are referred to as periodic background sync requests.
PeriodicSyncEvent
Represents a synchronization event, sent to the global scope of a ServiceWorker. It provides a way to run tasks in the service worker with network connectivity.

Service Worker Additions

The following additions to the Service Worker API are specified in the Periodic Background Sync specification to provide an entry point for using Periodic Background Sync.

ServiceWorkerRegistration.periodicSync Read only
Returns a reference to the PeriodicSyncManager interface for registering tasks to run at specific intervals.
ServiceWorkerGlobalScope.onperiodicsync
An event handler fired whenever a periodicsync event occurs. This happens at timed intervals, that are specified when registering a PeriodicSyncManager.

Examples

The following examples show how to use the interface.

Requesting a Periodic Background Sync

The following asynchronous function registers a periodic background sync at a minimum interval of one day from a browsing context:

async function registerPeriodicNewsCheck() {
  const registration = await navigator.serviceWorker.ready;
  try {
    await registration.periodicSync.register('fetch-news', {
      minInterval: 24 * 60 * 60 * 1000,
    });
  } catch {
    console.log('Periodic Sync could not be registered!');
  }
}

Verifying a Background Periodic Sync by Tag

This code checks to see if a Periodic Background Sync task with a given tag is registered.

navigator.serviceWorker.ready.then(registration => {
  registration.periodicSync.getTags().then(tags => {
    if (tags.includes('get-latest-news'))
      skipDownloadingLatestNewsOnPageLoad();
  });  
});

Removing a Periodic Background Sync Task

The following code removes a Periodic Background Sync task to stop articles syncing in the background.

navigator.serviceWorker.ready.then(registration => {
  registration.periodicSync.unregister('get-latest-news');
});

Listening for a Periodic Background Sync within a Service Worker

The following example shows how to respond to a periodic sync event in the service worker.

self.addEventListener('periodicsync', event => {
  if (event.tag == 'get-latest-news') {
    event.waitUntil(fetchAndCacheLatestNews());
  }
});

Specifications

Specification Status Comment
Web Periodic Background Synchronization Working Draft Initial definition.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
PeriodicSyncManager
ExperimentalNon-standard
Chrome Full support 80Edge Full support 80Firefox No support NoIE No support NoOpera Full support 67Safari No support NoWebView Android Full support 80Chrome Android Full support 80Firefox Android No support NoOpera Android Full support 57Safari iOS No support NoSamsung Internet Android Full support 13.0
getTags
ExperimentalNon-standard
Chrome Full support 80Edge Full support 80Firefox No support NoIE No support NoOpera Full support 67Safari No support NoWebView Android Full support 80Chrome Android Full support 80Firefox Android No support NoOpera Android Full support 57Safari iOS No support NoSamsung Internet Android Full support 13.0
register
ExperimentalNon-standard
Chrome Full support 80Edge Full support 80Firefox No support NoIE No support NoOpera Full support 67Safari No support NoWebView Android Full support 80Chrome Android Full support 80Firefox Android No support NoOpera Android Full support 57Safari iOS No support NoSamsung Internet Android Full support 13.0
unregister
ExperimentalNon-standard
Chrome Full support 80Edge Full support 80Firefox No support NoIE No support NoOpera Full support 67Safari No support NoWebView Android Full support 80Chrome Android Full support 80Firefox Android No support NoOpera Android Full support 57Safari iOS No support NoSamsung Internet Android Full support 13.0

Legend

Full support  
Full support
No support  
No support
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.
Non-standard. Expect poor cross-browser support.
Non-standard. Expect poor cross-browser support.

See also