The ServiceWorkerGlobalScope.onsync event of the ServiceWorkerGlobalScope interface is fired whenever a SyncEvent event occurs. This is triggered when a call to SyncManager.register is made from a service worker client page. The attempt to sync is made either immediately if the network is available or as soon as the network becomes available. 


ServiceWorkerGlobalScope.onsync = function(SyncEvent) { ... }
self.addEventListener('sync', function(SyncEvent) { ... })


Specification Status Comment
Web Background Synchronization
The definition of 'onsync' in that specification.
Living Standard Adds the onsync event.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support49 ?441 No24 No
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support4949 ?4424 No5.0

1. Service workers (and Push) have been disabled in the Firefox 45 and 52 Extended Support Releases (ESR).

Document Tags and Contributors

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