PushSubscription: getKey() method

getKey(name)

reg.pushManager.getSubscription().then((subscription) => {
  // Enable any UI which subscribes / unsubscribes from
  // push messages.

  subBtn.disabled = false;

  if (!subscription) {
    console.log("Not yet subscribed to Push");
    // We aren't subscribed to push, so set UI
    // to allow the user to enable push
    return;
  }

  // Set your UI to show they have subscribed for
  // push messages
  subBtn.textContent = "Unsubscribe from Push Messaging";
  isPushEnabled = true;

  // initialize status, which includes setting UI elements for subscribed status
  // and updating Subscribers list via push
  const endpoint = subscription.endpoint;
  const key = subscription.getKey("p256dh");
  const auth = subscription.getKey("auth");

  // …
});