Passing local node JS HTTP server port (running in electron) to angular service

I am running a RESTful node JS Http server on localhost within in my electron app. I listen on port 0, so that the OS gives me a random free port. How can I access the givin port within my angular code to be able to know on which URL I have to perform XHTTP requests?

restapi server (nodejs) running on 127.0.0.1:0

var listener = app.listen(port, server, function() { port = listener.address().port; console.log('Listening on port ' + port + '@' + server); });

XHTTP call in angular

private heroesUrl = 'http://localhost:1337/api/heroes';

getHeroes(): Promise { return this.http.get(this.heroesUrl).toPromise().then( ((response) => response.json() as Hero[]) ).catch(this.handleError); }

Any idea how I can replace the fixed port 1337 with the port that I get when opening the listener on the server side?

Or should I just use a fixed port on both sides and hope that it free? Sounds wrong to me.

Also I cant just go for '/api/heroes' as URL, because electron/angular is running on http://localhost:4200 (ng serve).

via capc0