nw-menu.js

var gui = require('nw.gui');

var menu = new gui.Menu({type:"menubar"});

// Only called on OS X
if (menu.createMacBuiltin !== undefined) {
  menu.createMacBuiltin("Recorder");
}

menu.append(new gui.MenuItem({
  label: 'Item A',
  click: function() {
    console.log("Item A clicked!");
  }
}));

gui.Window.get().menu = menu;