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Last active January 6, 2022 17:47
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Electron Fiddle Gist
Raw
index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Context Bridge Example</title>
<link rel="stylesheet" type="text/css" href="./styles.css">
</head>
<body>
<main class="app">
<button onclick="window.app.setFullscreen(true)">Enter fullscreen</button>
<button onclick="window.app.setFullscreen(false)">Exit fullscreen</button>
</main>
</body>
</html>
Raw
main.js
// Modules to control application life and create native browser window
const {app, BrowserWindow, ipcMain} = require('electron')
const path = require('path')
function createWindow () {
// Create the browser window.
const mainWindow = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
allowRunningInsecureContent: false,
contextIsolation: true,
enableRemoteModule: false,
nodeIntegration: false,
sandbox: true,
preload: path.join(app.getAppPath(), 'preload.js'),
}
})
// and load the index.html of the app.
mainWindow.loadFile('index.html')
// Open the DevTools.
// mainWindow.webContents.openDevTools()
ipcMain.handle('setFullscreen', (event, flag) => {
if (mainWindow) {
mainWindow.setFullScreen(flag)
}
})
}
// 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 (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
Raw
preload.js
const { ipcRenderer, contextBridge } = require('electron')
contextBridge.exposeInMainWorld(
'app',
{
setFullscreen: (flag) => ipcRenderer.invoke('setFullscreen', flag),
}
)
Raw
styles.css
.app {
text-align: center;
margin: 10rem;
}
@silveradd001
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Hi Matt,

Thank you very much for the example and your article "Safer Electron apps with ContextBridge" was of help for my current endeavour with electron

There is one thing though that I do not get yet, how do you successfully use "require('./renderer.js')" in the index.html script section?

For me it always fails at execution time with the following error message:

Uncaught ReferenceError: require is not defined
at index.html:21

What I am trying to understand is; how do you successfully use the nodejs directive "require" in the inline script tag?

Other than this little detail, very nice explanation,

Thanks,

Alex.

@matt-allan
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Author

Oh sorry, that line and comment was added by default by Electron Fiddle and I didn't notice it. You can't use require because nodeIntegration is set to false. nodeIntegration enables all the modules you're trying to avoid with contextBridge so I would suggest keeping it disabling and specifying the APIs you need to use with contextBridge.exposeInMainWorld instead.

@silveradd001
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Well now that does make sense indeed, otherwise, why disabling nodeIntegration if it is to be able to require node extensions ^^'

Anyway, thank you for coming back to me on this!

I wanted to make sure this was a typo and not something I didn't understand!

@raphael10-collab
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raphael10-collab commented Feb 11, 2021 •
edited

@matt-allan
tried to follow your example and transpose it into an Electron-Typescript-React-Webpack app, but I'm encountering this problem: Cannot read property 'setFullscreen' of undefined :

preload.js :

const {
  contextBridge,
  ipcRenderer
} = require("electron")

contextBridge.exposeInMainWorld(
  "api", {
      {
        setFullscreen: (flag) => ipcRenderer.invoke('setFullscreen', flag),
      }
  }
)

global.ts :

export {}
declare global {
  interface Window {
    "api": {
      setFullscreen: (flag) => void;
    }
  }
}

main.ts :

let mainWindow: BrowserWindow;

const createWindow = (): void => {
  // Create the browser window.
  mainWindow = new BrowserWindow({
    height: 600,
    width: 800,
    backgroundColor: '#242424',
    webPreferences: {
      nodeIntegration: false,
      enableRemoteModule: false,
      contextIsolation: true,
      nodeIntegrationInWorker: false,
      nodeIntegrationInSubFrames: false,
      webSecurity: true,
      webviewTag: false,
      preload: './preload/preload',
      devTools: process.env.NODE_ENV !== 'production',
    },
  });
  mainWindow.webContents.openDevTools();

  // and load the index.html of the app.
  mainWindow.loadURL(
    url.format({
      pathname: path.join(__dirname, './index.html'),
      protocol: 'file:',
      slashes: true,
    }),
  ).finally(() => { /* no action */ });

  ipcMain.handle('setFullscreen', (event, flag) => {
    if (mainWindow) {
      mainWindow.setFullScreen(flag);
    }
  });

  mainWindow.on('close', () => {
    console.log('Closing WindowTypeA...');
  });
}

in the renderer process App.tsx :

import * as React from 'react';
function App() {
  const toggleFullScreen = (flag: boolean) => {
    window.api.setFullscreen(flag);
  }

  return (
    <div className='container'>
      <h2 className='heading'>
          Multiple Selective Windows Communication
      </h2>
         <p>
           <button onClick={() => {
             toggleFullScreen(true);
             }}>Enter fullscreen</button>

           <button onClick={() => {
             toggleFullScreen(false);
             }}>Exit fullscreen</button>

         </p>
</div>

);

image

If I set in App.tsx :

const sendProxy = window.api.send;

I get the same error and the window is not rendered :

image

What am I doing wrongly? How to solve the problem?

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