What is the difference between `pushManager.subscribe` and` pushManager.getSubscription` Service Worker's

Question

PushManager.getSubscription ()

Retrieves an existing push subscription. It returns a promise that resolves the PushSubscription object containing information about the existing subscription. If an existing subscription does not exist, this eliminates the null value.

[...]

PushManager.subscribe ()

Subscribes to the push service. It returns a promise that resolves the PushSubscription object containing the push subscription information. A new push subscription is created if the current service employee does not have an existing subscription.

According to MDN documentation pushManager . There, the methods are almost identical, except that in the case of getSubcription() it can be resolved with a null value.

I basically understand that I can just use subscribe() , and Service Worker will try to get a subscription if it is available, and also create a new one if it is not available.

=> But I tried to do something else. First I want to try to get a subscription, if it is allowed using null , I will try to subscribe to it.

  navigator.serviceWorker.register('./worker.js') .then(function(reg) { // Subscribe push manager reg.pushManager.getSubscription() .then(function(subscription) { if(subscription){ // TODO... get the enpoint here } else { reg.pushManager.subscribe() .then(function(sub){ // TODO... get the endpoint here }); } }, function(error) { console.error(error); }) }); 

But then I ended up with an error:

Unprepared (in promise) DOMException: subscription failed - no active Service Worker

This is confusing, and I doubt that this is a limitation of Chrome on the Push API working, or may be a mistake. Does anyone have any information about this strange behavior?

Answer 1

The problem is that your service worker is registered, but not yet activated.

You can use navigator.serviceWorker.ready instead of subscribing immediately after registering the worker.

If you want to activate a service worker as soon as possible, you can use skipWaiting and Clients.claim , as described in this CookbookWorker recipe .