How can I access the BrowserWindow JavaScript global from the main process in Electron?

Here is a reference to your comment about the webContents process in the API, in the “Note:” under remotes.

However, if you just want to trigger a function, you could also use the webContents.send() and ipc(main process) processes to trigger the appropriate code to run. Something like this…

// JavaScript inside the main process
const window = require('electron').BrowserWindow;

ipc.on('menuItem-selected', function(){
    let focusedWindow    = window.getFocusedWindow();
    focusedWindow.webContents.send('file-save');
});

// Inside the menu callback
require('ipc').on('file-save', function() {
  // File save function call here
});

For Electron version 0.35.0 and above, the ipc API changed to the following:

// In main process.
const ipcMain = require('electron').ipcMain;

// In renderer process (web page).
const ipcRenderer = require('electron').ipcRenderer;