Web Push API in Firefox

When I was playing around with the Web Push API, I worked exclusively with Google Chrome. It looked like Google had spearheaded this browser feature, and at some points they required the developer to interact with GCM/FCM. It was pretty unclear how (or whether) any of this worked with Firefox.

I ran the following JavaScript in Firefox:

navigator.serviceWorker.ready.then(reg => {
  reg.pushManager.subscribe({userVisibleOnly: true}).then(sub => {
    console.log("Subscription:", sub);
    window.sub = sub;
  });
})

Here’s the subscription object I get:

{
  "endpoint": "https://updates.push.services.mozilla.com/wpush/v1/<BIG_STRING>",
  "keys": {
    "auth": "<BIG_STRING>",
    "p256dh": "<BIG_STRING>"
  }
}

Compare this to the subscription object I get in Google Chrome:

{
  "endpoint": "https://android.googleapis.com/gcm/send/<BIG_STRING>",
  "expirationTime":null,
  "keys": {
    "auth": "<BIG_STRING>",
    "p256dh": "<BIG_STRING>"
  }
}

What is updates.push.services.mozilla.com? It’s part of the Mozilla Push Service! Specifically, it’s the domain that the server component of web applications can send notifications to. There is another domain, push.services.mozilla.com, that browsers holds open connections to, waiting for new pushes.

It looks like Google (?) are rolling out several Web Push libraries, but there’s no official Go library yet. However, I was able to send a notification to this subscription using the Go library SherClockHolmes/webpush-go. This looks something like:

package main
import (
	"bytes"
	"encoding/json"
	"log"
	webpush "github.com/sherclockholmes/webpush-go"
)
func main() {
	s := webpush.Subscription{}
  err := json.NewDecoder(bytes.NewBufferString(`{ THE JSON SUBSCRIPTION DATA }`)).Decode(&s)
	if err != nil {
		log.Fatal(err)
	}
	_, err = webpush.SendNotification(
    []byte(`{"method": "notification", "title": "Hello"}`),
    &s,
    &webpush.Options{ VAPIDPrivateKey: "MY VAPID KEY" }
  )
	if err != nil {
		log.Fatal(err)
	}
}

I wrote this because I felt like it. This post is not associated with my employer.