My first Javascript app

Last night I tried to make a small app/script in javascript (gjs) and it actually worked. :) Here is the code:

const GLib = imports.gi.GLib;
const GUPnP = imports.gi.GUPnP;
const Mainloop = imports.mainloop;

// This doesn't start any threads
GLib.thread_init (null);

let context = new GUPnP.Context ({ main_context: null,
                                   host_ip: null,
                                   port: 0
});

let cp = new GUPnP.ControlPoint ({ client: context,
                                   target: "ssdp:all"
});

function onDeviceProxyAvailable (cp, proxy) {
        log (proxy.get_friendly_name ());
}

// Tell us when there is a new device available
cp.connect ("device-proxy-available", onDeviceProxyAvailable);

// Search and listen for UPnP resources on the network
cp.set_active (true);

Mainloop.run ("0");