PushSubscriptionOptions.applicationServerKey

The applicationServerKey read-only property of the PushSubscriptionOptions interface contains the public key used by the push server.

A public key your push server uses to send messages to client apps via a push server. This value is part of a signing key pair generated by your application server, and usable with elliptic curve digital signature (ECDSA), over the P-256 curve.

In the example below the value of applicationServerKey is printed to the console.

navigator.serviceWorker.ready.then(function(reg) {
  reg.pushManager.getSubscription().then(function(subscription) {
    let options = subscription.options;
    console.log(options.applicationServerKey); // the public key
  })
});