The new web APIs are promise-ified by default rather than using the callback model of the past. So rather than register(callback), it's register().then(...).
Whether this is a good thing or not is another question I don't know the answer to.
My comment was mainly about serviceWorker.ready.then.
I've never seen a JS API using such pattern - the name of the event as a property which is a promise.
A manager object/class also usually rings a bell.
Not that I'm an API specialist but I would rather implement it as:
document.addEventListener("serviceready", function() {
window.pushNotification.register().then(.....
For an event that only happens once, then the
navigator.serviceWorker.ready.then(function(){...
document.addEventListener("serviceready", function() {
The idea behind this is awesome (although we already have this for some platforms - e.g. https://developer.apple.com/library/mac/documentation/Networ...)
But the API looks over-engineered. e.g.
navigator.serviceWorker.ready.then(function(serviceWorkerRegistration) {
serviceWorkerRegistration.pushRegistrationManager.register().then(...