The PeriodicSyncEvent interface of the Web Periodic Background Synchronization API provides a way to run tasks in the service worker with network connectivity.

An instance of this event is passed to the periodicsync handler. This happens periodically, at an interval greater than or equal to that set in the PeriodicSyncManager.register() method. Other implementation-specific factors such as the user's engagement with the site decide the actual interval.

PeriodicSyncEvent.PeriodicSyncEvent() Experimental

Creates a new PeriodicSyncEvent object. This constructor is not typically used. The browser creates these objects itself and provides them to onperiodicsync callback.

PeriodicSyncEvent.tag Read only Experimental

Returns the developer-defined identifier for this PeriodicSyncEvent. Multiple tags can be used by the web app to run different periodic tasks at different frequencies.

Inherits methods from its parent ExtendableEvent.

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());
  }
});

fetchAndCacheLatestNews is a developer defined function.

• Richer offline experiences with the Periodic Background Sync API
• A Periodic Background Sync demo app