Is it possible to externalize Electron menu template code?

I have an Electron app with 3 windows and each window has a different menu. The menu template code for each menu is quite long and I would like to externalize it. So far nothing I have tried works.

I've tried different ways to "modularize" it but got lots of errors. The approach below works to set up the menu, but none of the functions referenced in the menu work (e.g. quitApplication).

Is what I am trying to do not possible or am I just "doing it wrong"?

var test = require("./app/js/menuTest.js");
var tm = new test();    
var menuTemplate = tm.getMenu();
myWindow = Menu.buildFromTemplate(menuTemplate);

menuTest.js

function testMenu() {
 this.getMenu = function () {
        var menuTemplate = [
            {
                label: global.productData.appName,
                submenu: [
                    { label: 'About ' + global.productData.appName, click: () => { showAboutWindow() } },

                    { type: 'separator' },
                    { role: 'hide' },
                    { role: 'hideothers' },
                    { role: 'unhide' },
                    { type: 'separator' },
                    { label: 'Quit', click: () => { quitApplication() }, accelerator: 'CmdOrCtrl+q' }
                ]
         // code deleted for clarity
        return menuTemplate;
    }
}
module.exports = testMenu;