Adding link to payload

[Katastrophenmagnet]

Right now I am using this very example for a small project of mine and have a small issue.
I added a clickListener on the notification, so that the user follows a certain link upon clicking the notification. Looks like this and works fine:

from my serviceWorker.js

self.addEventListener('notificationclick', function(event) {  
  event.notification.close();

  // This looks to see if the current is already open and  
  // focuses if it is  
  event.waitUntil(
    clients.matchAll({  
      type: "window"  
    })
    .then(function(clientList) { 
	  console.log(clientList); 
      for (var i = 0; i < clientList.length; i++) {  
        var client = clientList[i];  
        if (client.url == '/' && 'focus' in client)  
          return client.focus();  
      }  
      if (clients.openWindow) {
	     console.log(clients.openWindow);
        return clients.openWindow(LINK);  
      }
    })
  );
}

My problem is that the link is a variable in serviceWorker.js but I'd like it to be sent from the backend, therefore I'd like to attach the data (link) in the file send_push_notification.php at this part:

$res = $webPush->sendNotification( $subscription, "Hello!", true );

and then read it somewhere here in the serviceWorker.js

self.addEventListener('push', function (event) {
	eventData = event.data;
    if (!(self.Notification && self.Notification.permission === 'granted')) {
        return;
    }

    const sendNotification = body => {
        // you could refresh a notification badge here with postMessage API
        const title = "Web Push example";

        return self.registration.showNotification(title, {
            body,
        });
    };

    if (event.data) {
        const message = event.data.text();
        event.waitUntil(sendNotification(message));
    }
});

Could you please explain me how exactly this would be done? I am somewhat confused since I am not fit in php (need it though), tried some stuff, nothing really seemed to do the trick.

Thank you!

[Katastrophenmagnet]

Hello!
Just wanted to let you know, that after some time of trying I found out that one possibility would be to just add a json object here instead of "Hello!":

$res = $webPush->sendNotification( $subscription, "Hello!", true );

and then read it via event.data.json() instead of event.data.text() here:

if (event.data) { const message = event.data.text(); event.waitUntil(sendNotification(message)); }

Sorry and thank you!

If you have better ideas I am all ears.

BTW: Is there some good and exact documentation for all this?

[Minishlink]

Hello,
Cool that you found the solution by yourself. You have several examples here, I highly recommend the Web Push book.