Add Electron example (#1430)

* Add Electron usage example

* Remove the deploy part

* Only allow GET request to our HTTP server

* Only allow request from an electron app (checking the user agent)

* Add warning about the local HTTP server

* Update package.json

* Update example to use Next.js v3

* Added required package.json fields with placeholders

* Use next:// file protocol to open internal built files

* Create next.config.js

* Update set-menu.js

* Update example to merge it with electron-next-skeleton ideas

examples/with-electron/README.md

@@ -0,0 +1,25 @@
+# Electron application example
+
+## How to use
+
+Download the example [or clone the repo](https://github.com/zeit/next.js):
+
+```bash
+curl https://codeload.github.com/zeit/next.js/tar.gz/master | tar -xz --strip=2 next.js-master/examples/with-electron
+cd with-electron
+```
+
+Install it and run:
+
+```bash
+npm install
+npm start
+```
+
+## The idea behind the example
+
+This example show how you can use Next.js inside an Electron application to avoid a lot of configuration, use Next.js router as view and use server-render to speed up the initial render of the application.
+
+For development it's going to run a HTTP server and let Next.js handle routing. In production it use `next export` to pre-generate HTML static files and use them in your app instead of running an HTTP server.
+
+You can create the production app using `npm run dist`.

examples/with-electron/main/index.js

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+// Native
+const { join } = require('path')
+const { format } = require('url')
+
+// Packages
+const { BrowserWindow, app, ipcMain } = require('electron')
+const isDev = require('electron-is-dev')
+const prepareNext = require('electron-next')
+
+// Prepare the renderer once the app is ready
+app.on('ready', async () => {
+  await prepareNext('./renderer')
+
+  const mainWindow = new BrowserWindow({
+    width: 800,
+    height: 600
+  })
+
+  const url = isDev
+    ? 'http://localhost:8000/start'
+    : format({
+      pathname: join(__dirname, '../renderer/start/index.html'),
+      protocol: 'file:',
+      slashes: true
+    })
+
+  mainWindow.loadURL(url)
+})
+
+// Quit the app once all windows are closed
+app.on('window-all-closed', app.quit)
+
+// listen the channel `message` and resend the received message to the renderer process
+ipcMain.on('message', (event, message) => {
+  event.sender.send('message', message)
+})

examples/with-electron/package.json

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+{
+  "name": "electron-next-skeleton",
+  "productName": "ElectronNext",
+  "version": "1.0.0",
+  "main": "main/index.js",
+  "scripts": {
+    "start": "electron .",
+    "build": "next build renderer && next export renderer",
+    "dist": "npm run build && build --dir"
+  },
+  "build": {
+    "asar": false,
+    "extraResources": [
+      {
+        "from": "renderer/out",
+        "to": "app/renderer"
+      }
+    ]
+  },
+  "devDependencies": {
+    "electron": "^1.6.11",
+    "electron-builder": "^19.19.1",
+    "next": "beta",
+    "react": "15.6.1",
+    "react-dom": "15.6.1"
+  },
+  "dependencies": {
+    "electron-is-dev": "0.3.0",
+    "electron-next": "3.0.8"
+  }
+}

examples/with-electron/renderer/next.config.js

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+module.exports = {
+  webpack (config, { dev }) {
+    config.target = 'electron-renderer'
+    return config
+  },
+  exportPathMap () {
+    // Let Next.js know where to find the entry page
+    // when it's exporting the static bundle for the use
+    // in the production version of your app
+    return {
+      '/start': { page: '/start' }
+    }
+  }
+}

examples/with-electron/renderer/pages/start.js

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+import { Component } from 'react'
+import { ipcRenderer } from 'electron'
+
+export default class extends Component {
+  state = {
+    input: '',
+    message: null
+  }
+
+  componentDidMount () {
+    // start listening the channel message
+    ipcRenderer.on('message', this.handleMessage)
+  }
+
+  componentWillUnmount () {
+    // stop listening the channel message
+    ipcRenderer.removeListener('message', this.handleMessage)
+  }
+
+  handleMessage = (event, message) => {
+    // receive a message from the main process and save it in the local state
+    this.setState({ message })
+  }
+
+  handleChange = event => {
+    this.setState({ input: event.target.value })
+  }
+
+  handleSubmit = event => {
+    event.preventDefault()
+    ipcRenderer.send('message', this.state.input)
+    this.setState({ message: null })
+  }
+
+  render () {
+    return (
+      <div>
+        <h1>Hello Electron!</h1>
+
+        {this.state.message &&
+          <p>{this.state.message}</p>
+        }
+
+        <form onSubmit={this.handleSubmit}>
+          <input type='text' onChange={this.handleChange} />
+        </form>
+
+        <style jsx>{`
+          h1 {
+            color: red;
+            font-size: 50px;
+          }
+        `}</style>
+      </div>
+    )
+  }
+}