How can i use additionalData in push notification?

I am a newbie of ionic.
I’m looking for a solution to handle notification but i don’t know how i can to send a custom parameter.
I want to pass Id to notification.
I found from google and it said that i can use “additionalData” and nothing much.
my code:

 "notification": {   
                     "title": "hello",
                    "message": "My test" ,
                             "id": 1

And in “app.component.ts”:

    .subscribe((msg: any) => { 
         var id =;//
           //call alert(...)

I suspect it is wrong because i didn’t get any notification when i used this code.
please help.