connect signals with Gtk & Gjs

function test(data){
    var builder = new Gtk.Builder();
    builder.add_from_file("window.ui");
    var handlers = {
            on_quit: Gtk.main_quit
        };
    let signal_handlers = new SignalHandlers();
    builder.connect_signals_full(function(builder, object, signal, handler){
            object.connect(signal,handlers[handler]);
        },this);
    var win = builder.get_object("window");

    this.show_all = function(widget){
        win.show_all();
    }
}