electron/atom/browser/default_app/default_app.js

const electron = require('electron');
const app = electron.app;
const BrowserWindow = electron.BrowserWindow;

var mainWindow = null;

// Quit when all windows are closed.
app.on('window-all-closed', function() {
  app.quit();
});

exports.load = function(appUrl) {
  app.on('ready', function() {
    mainWindow = new BrowserWindow({
      width: 800,
      height: 600,
      autoHideMenuBar: true,
      useContentSize: true,
    });
    mainWindow.loadURL(appUrl);
    mainWindow.focus();
  });
};