electron-Menu建立原生應用菜單和上下文菜單。

當在MacOS、Windows、Linux中使用menu設置程序菜單時，會設置在各個程序窗體的頂層。

Note: 若是沒有在app中設置一個菜單，系統會自動生成一個默認菜單， 默認生成的菜單中包含了一些初始選項，例如 文件,編輯, 視圖,窗口,幫助。

app.on('ready', function () {
  createWindow ();createMenu();
});
function createMenu(){
  const {app, Menu} = require('electron');
  const template = [
    {
      label: 'Edit',
      submenu: [
        {role: 'undo'},
        {role: 'redo'},
        {type: 'separator'},
        {role: 'cut'},
        {role: 'copy'},
        {role: 'paste'},
        {role: 'pasteandmatchstyle'},
        {role: 'delete'},
        {role: 'selectall'}
      ]
    },
    {
      label: 'View',
      submenu: [
        {role: 'reload'},
        {role: 'forcereload'},
        {role: 'toggledevtools'},
        {type: 'separator'},
        {role: 'resetzoom'},
        {role: 'zoomin'},
        {role: 'zoomout'},
        {type: 'separator'},
        {role: 'togglefullscreen'}
      ]
    },
    {
      role: 'window',
      submenu: [
        {role: 'minimize'},
        {role: 'close'}
      ]
    },
    {
      role: 'help',
      submenu: [
        {
          label: 'Learn More',
          click () { require('electron').shell.openExternal('https://electron.atom.io'); }
        }
      ]
    }
  ];

  if (process.platform === 'darwin') {
    template.unshift({
      label: app.getName(),
      submenu: [
        {role: 'about'},
        {type: 'separator'},
        {role: 'services', submenu: []},
        {type: 'separator'},
        {role: 'hide'},
        {role: 'hideothers'},
        {role: 'unhide'},
        {type: 'separator'},
        {role: 'quit'}
      ]
    });

    // Edit menu
    template[1].submenu.push(
        {type: 'separator'},
        {
          label: 'Speech',
          submenu: [
            {role: 'startspeaking'},
            {role: 'stopspeaking'}
          ]
        }
    );

    // Window menu
    template[3].submenu = [
      {role: 'close'},
      {role: 'minimize'},
      {role: 'zoom'},
      {type: 'separator'},
      {role: 'front'}
    ];
  }

  const menu = Menu.buildFromTemplate(template);
  Menu.setApplicationMenu(menu);
}