This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
mySyncManager = ServiceWorker.sync
|Web Background Synchronization||Living Standard||Initial definition.|
|Feature||Android webview||Chrome for Android||Edge mobile||Firefox for Android||Opera Android||iOS Safari||Samsung Internet|
1. From version 16: this feature is behind the
Enable service workers preference.
2. Service workers (and Push) have been disabled in the Firefox 45 and 52 Extended Support Releases (ESR).