update quick-start code to match quick-start repo

docs/tutorial/quick-start.md

@@ -80,45 +80,60 @@ The `main.js` should create windows and handle system events, a typical
 example being:
 
 ```javascript
-'use strict';
-
-const electron = require('electron');
-const app = electron.app;  // Module to control application life.
-const BrowserWindow = electron.BrowserWindow;  // Module to create native browser window.
+const electron = require('electron')
+// Module to control application life.
+const app = electron.app
+// Module to create native browser window.
+const BrowserWindow = electron.BrowserWindow
 
 // Keep a global reference of the window object, if you don't, the window will
 // be closed automatically when the JavaScript object is garbage collected.
-var mainWindow = null;
-
-// Quit when all windows are closed.
-app.on('window-all-closed', function() {
-  // On OS X it is common for applications and their menu bar
-  // to stay active until the user quits explicitly with Cmd + Q
-  if (process.platform != 'darwin') {
-    app.quit();
-  }
-});
+let mainWindow
 
-// This method will be called when Electron has finished
-// initialization and is ready to create browser windows.
-app.on('ready', function() {
+function createWindow () {
   // Create the browser window.
-  mainWindow = new BrowserWindow({width: 800, height: 600});
+  mainWindow = new BrowserWindow({width: 800, height: 600})
 
   // and load the index.html of the app.
-  mainWindow.loadURL('file://' + __dirname + '/index.html');
+  mainWindow.loadURL('file://' + __dirname + '/index.html')
 
   // Open the DevTools.
-  mainWindow.webContents.openDevTools();
+  mainWindow.webContents.openDevTools()
 
   // Emitted when the window is closed.
-  mainWindow.on('closed', function() {
+  mainWindow.on('closed', function () {
     // Dereference the window object, usually you would store windows
     // in an array if your app supports multi windows, this is the time
     // when you should delete the corresponding element.
-    mainWindow = null;
-  });
-});
+    mainWindow = null
+  })
+}
+
+// This method will be called when Electron has finished
+// initialization and is ready to create browser windows.
+// Some APIs can only be used after this event occurs.
+app.on('ready', createWindow)
+
+// Quit when all windows are closed.
+app.on('window-all-closed', function () {
+  // On OS X it is common for applications and their menu bar
+  // to stay active until the user quits explicitly with Cmd + Q
+  if (process.platform !== 'darwin') {
+    app.quit()
+  }
+})
+
+app.on('activate', function () {
+  // On OS X it's common to re-create a window in the app when the
+  // dock icon is clicked and there are no other windows open.
+  if (mainWindow === null) {
+    createWindow()
+  }
+})
+
+// In this file you can include the rest of your app's specific main process
+// code. You can also put them in separate files and require them here.
+
 ```
 
 Finally the `index.html` is the web page you want to show: