How should I open links on web-push notification click - service worker or"click_action"?

Question

I'm currently working on integrating Firebase Cloud Messaging (FCM) for push notifications in my web application. I have a question regarding the behavior of clicks on web-push notifications and how to define this behavior and gather information and analytics.

My question is some what similar to these questions:

• click_action attribute for web push notification through FCM
• Missing click-action key for webpush payload on message sent via FCM HTTPv1
• HTTP v1 API: "click_action" for webpush notification

However, there are some differences.

The Firebase documentation doesn't explicitly address whether to use click_action or service worker to handle click behavior.

I have read the Message Types article, which mentions two types of messages:

• Notification messages
• Data messages

But I didn't understand the difference between them.

Let's say I want end-users who receive notifications from my backend systems to be directed to example.com when they click on the notification.

I've achieved this using a service worker:

self.addEventListener("notificationclick", (event) => {
    const notificationData = event.notification.data;
    const targetPageUrl = notificationData && notificationData.tracking
    return clients.openWindow(targetPageUrl);
 }

As you can see, it parses the data field in the notification payload and then opens the URL.

Here's the payload I'm using:

"webpush": {
"notification": {
  "title": "This is a test notification",
  "body": "test test test",
  "data": {
    "tracking": "https://example.com?source=data_field"
  },
  "actions": [
    {
      "action": "yes",
      "title": "Enter to the site",
    },
    {
      "action": "no",
      "title": "Ignore",
    }
  ],
},
"fcm_options": {
  "link": "https://example.com?source=fcm_options"
 }
}

However, if I understand correctly from the Firebase documentation, I shouldn't need to do this. I can implement the URL in the payload as part of fcm_options.link, and this should handle the click operation without the need to handle it in the service worker.

But for some reason, it doesn't work for me - nothing happens when I click on the notification (if I remove the handling of the onclick from the service worker).

I would appreciate some assistance and clarification on how to handle the click behavior of web-push notifications by using the fcm_options.link field and without the need of the service worker.