I have an auth workflow that opens a window to an external URL. The URL redirects to another URL that returns a token. I need to retrieve that token in my application.

Right now I have the following code:

    const url = await retrieveAuthURL()
    console.log(`Redirecting to auth url ${url}`)
    if (url === null) {
      console.log('Received null auth url')
      return
    }
    window.open(url, '_blank', 'location=yes,height=700,width=600,scrollbars=0,status=1')
    window.addEventListener('message',handleEvent)

where handleEvent takes the event and mutates the state of the program to set the user info based on it. But the event doesn't fire - I am guessing because a redirect, differently from a fetch, doesn't count as an event?

How do I go about retrieving the auth information I need?