onbeforeunload event confirmation

I am using Laravel and Vue js. I am creating a wizard which has three steps. And I am using onbeforeunload event for showing if a person tries to do anything unwanted. Now the thing is this event will show a message saying Leave or Stay. When the person clicks on Leave button I want to perform a specific action and when the person clicks on Stay button I don’t want that action to be executed. Right now it is running every time. How can I update that?

What I have tried:

window.onbeforeunload = function(e){
                //action here
                e.returnValue =  "Changes may not be saved";
            }

Answer

In case anyone else is wondering about it.. you can do this by calling beforeunload event and onbeforeunload simultaneously. onbeforeunload will give the warning and beforeunload will perform your action.