In the example code, if the subscription object does not exist, the subscribeUser function is invoked. The service worker registration object is passed as the only parameter:
registration.pushManager.getSubscription().then(function (subscription) { if(subscription === null){ subscribeUser(registration); } });
The pushManager subscribe method has a single parameter, an object with two properties, userVisibleOnly and applicationServerKey.
The subscribe function returns a promise that resolves after the user has granted permission to send notifications and the browser sends a request to the push service.
As part of the subscribe function work flow, the User Agent is required to prompt the user for permission. ...
