电子 require() 未定义

Question

I'm creating an Electron app for my own purpose. My problem is when I'm using node functions inside my HTML page it throws an error of:

'require()' is not defined.

Is there any way to use Node functionalities in all my HTML pages? If it is possible please give me an example of how to do this or provide a link. Here are the variables I'm trying to use in my HTML page:

  var app = require('electron').remote; 
  var dialog = app.dialog;
  var fs = require('fs');

and these are the values I'm using in all my HTML windows within Electron.

Answer 1

As of version 5, the default for nodeIntegration changed from true to false. You can enable it when creating the Browser Window:

app.on('ready', () => {
    mainWindow = new BrowserWindow({
        webPreferences: {
            nodeIntegration: true,
            contextIsolation: false,
        }
    });
});

Answer 2

Edit 2022

---

I've published a larger post on the history of Electron and it's security that provides additional context on the changes that affect how security was approached in different framework versions (and what's the best approach to take).

Original answer

---

I hope this answer gets some attention, because a large majority of answers here leave large security holes in your electron app. In fact this answer is essentially what you should be doing to use require() in your electron apps. (There is just a new electron API that makes it a little bit cleaner in v7).

I wrote a detailed explanation/solution in github using the most current electron apis of how you can require() something, but I'll explain briefly here why you should follow an approach using a preload script, contextBridge and ipc.

The problem

Electron apps are great because we get to use node, but this power is a double-edged sword. If we are not careful, we give someone access to node through our app, and with node a bad actor can corrupt your machine or delete your operating system files (among other things, I imagine).

As brought up by @raddevus in a comment, this is necessary when loading remote content. If your electron app is entirely offline / local , then you are probably okay simply turning on nodeIntegration:true . I still would, however, opt to keep nodeIntegration:false to act as a safeguard for accidental/malicious users using your app, and prevent any possible malware that might ever get installed on your machine from interacting with your electron app and using the nodeIntegration:true attack vector (incredibly rare, but could happen)!

What does the problem look like

This problem manifests when you (any one of the below):

1. Have nodeIntegration:true enabled
2. Use the remote module

All of these problems give uninterrupted access to node from your renderer process. If your renderer process is ever hijacked, you can consider all is lost.

What our solution is

The solution is to not give the renderer direct access to node (ie. require() ), but to give our electron main process access to require , and anytime our renderer process needs to use require , marshal a request to the main process.

The way this works in the latest versions (7+) of Electron is on the renderer side we set up ipcRenderer bindings, and on the main side we set up ipcMain bindings. In the ipcMain bindings we set up listener methods that use modules we require() . This is fine and well because our main process can require all it wants.

We use the contextBridge to pass the ipcRenderer bindings to our app code (to use), and so when our app needs to use the require d modules in main, it sends a message via IPC (inter-process-communication) and the main process runs some code, and we then send a message back with our result.

Roughly , here's what you want to do.

main.js

const {
  app,
  BrowserWindow,
  ipcMain
} = require("electron");
const path = require("path");
const fs = require("fs");

// 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.
let win;

async function createWindow() {

  // Create the browser window.
  win = new BrowserWindow({
    width: 800,
    height: 600,
    webPreferences: {
      nodeIntegration: false, // is default value after Electron v5
      contextIsolation: true, // protect against prototype pollution
      enableRemoteModule: false, // turn off remote
      preload: path.join(__dirname, "preload.js") // use a preload script
    }
  });

  // Load app
  win.loadFile(path.join(__dirname, "dist/index.html"));

  // rest of code..
}

app.on("ready", createWindow);

ipcMain.on("toMain", (event, args) => {
  fs.readFile("path/to/file", (error, data) => {
    // Do something with file contents

    // Send result back to renderer process
    win.webContents.send("fromMain", responseObj);
  });
});

preload.js

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

// Expose protected methods that allow the renderer process to use
// the ipcRenderer without exposing the entire object
contextBridge.exposeInMainWorld(
    "api", {
        send: (channel, data) => {
            // whitelist channels
            let validChannels = ["toMain"];
            if (validChannels.includes(channel)) {
                ipcRenderer.send(channel, data);
            }
        },
        receive: (channel, func) => {
            let validChannels = ["fromMain"];
            if (validChannels.includes(channel)) {
                // Deliberately strip event as it includes `sender` 
                ipcRenderer.on(channel, (event, ...args) => func(...args));
            }
        }
    }
);

index.html

<!doctype html>
<html lang="en-US">
<head>
    <meta charset="utf-8"/>
    <title>Title</title>
</head>
<body>
    <script>
        window.api.receive("fromMain", (data) => {
            console.log(`Received ${data} from main process`);
        });
        window.api.send("toMain", "some data");
    </script>
</body>
</html>

Disclaimer

I'm the author of secure-electron-template , a secure template to build electron apps. I care about this topic, and have been working on this for a few weeks (at this point in time).

Answer 3

For security reasons, you should keep nodeIntegration: false and use a preload script to expose just what you need from Node/Electron API to the renderer process (view) via window variable. From the Electron docs :

Preload scripts continue to have access to require and other Node.js features

---

Example

main.js

const mainWindow = new BrowserWindow({
  webPreferences: {
    preload: path.join(app.getAppPath(), 'preload.js')
  }
})

preload.js

const { remote } = require('electron');

let currWindow = remote.BrowserWindow.getFocusedWindow();

window.closeCurrentWindow = function(){
  currWindow.close();
}

renderer.js

let closebtn = document.getElementById('closebtn');

closebtn.addEventListener('click', (e) => {
  e.preventDefault();
  window.closeCurrentWindow();
});

Answer 4

First off, @Sathiraumesh solution leaves your electron application with huge security issue. Imagine that your app is adding some extra features to messenger.com , for example toolbar's icon will change or blink when you've have unread message. So in your main.js file, you create new BrowserWindow like so (notice I intentionally misspelled messenger.com):

app.on('ready', () => {
    const mainWindow = new BrowserWindow({
        webPreferences: {
            nodeIntegration: true
        }
    });
    mainWindow.loadURL(`https://messengre.com`);
});

What if messengre.com is a malicious website, that wants to harm your computer. If you set nodeIntegration: true this site has access to your local file system and can execute this:

require('child_process').exec('rm -r ~/');

And your home directory is gone.

Solution
Expose only what you need, instead of everything. This is achived by preloading javascript code with require statements.

// main.js
app.on('ready', () => {
    const mainWindow = new BrowserWindow({
        webPreferences: {
            preload: `${__dirname}/preload.js`
        }
    });
    mainWindow.loadURL(`https://messengre.com`);
});

// preload.js
window.ipcRenderer = require('electron').ipcRenderer;

// index.html
<script>
    window.ipcRenderer.send('channel', data);
</script>

Now awful messengre.com cannot delete your entire file system.

Answer 5

It looks like Electron's security evolved like this ( source ).

Electron 1 nodeIntegration defaults to true

Renderer has full access to Node API -- huge security risks if Renderer loads remote code.

Electron 5 nodeIntegration defaults to false

When set to false, a preload script is used to expose specific API to Renderer. (The preload script always has access to Node APIs regardless of the value of nodeIntegration )

//preload.js
window.api = {
    deleteFile: f => require('fs').unlink(f)
}

Electron 5 contextIsolation defaults to true (actually still defaults to false in Electron 11)

This causes preload script to run in a separate context. You can no longer do window.api = ... . You now have to do:

//preload.js
const { contextBridge } = require('electron')

contextBridge.exposeInMainWorld('api', {
    deleteFile: f => require('fs').unlink(f)
})

Electron 6 require() ing node builtins in sandboxed renderers no longer implicitly loads the remote version

If Renderer has sandbox set to true, you have to do:

//preload.js
const { contextBridge, remote } = require('electron')

contextBridge.exposeInMainWorld('api', {
    deleteFile: f => remote.require('fs').unlink(f)
})

Electron 10 enableRemoteModule default to false ( remote module deprecated in Electron 12)

The remote module is used when you need to access Node APIs from a sandboxed Renderer (as in above example); or when you need to access Electron APIs that are available only to the Main process (such as dialog, menu). Without remote , you'll need to write explicit IPC handlers like follows.

//preload.js
const { contextBridge, ipcRenderer } = require('electron')

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

//main.js
const { ipcMain, dialog } = require('electron')

ipcMain.handle("displayMessage", text => dialog.showMessageBox(text))

Electron 10 deprecate nodeIntegration flag (removed in Electron 12)

Recommendation

Always set {nodeIntegration: false, contextIsolation: true, enableRemoteModule: false} .

For max security, set {sandbox: true} . Your preload script will have to use IPC to call the Main process to do everything .

If sandbox is false, your preload script can access Node API directly, as in require('fs').readFile . You're secure as long as you don't this:

//bad
contextBridge.exposeInMainWorld('api', {
    readFile: require('fs').readFile
})

Answer 6

Are you using nodeIntegration: false while BrowserWindow initialization? If so, set it to true (defaults value is true ).

And include your external scripts in the HTML like this (not as <script> src="./index.js" </script> ):

<script>
   require('./index.js')
</script>

Answer 7

All I wanted to do was to require a js file in my html page because of the tutorial I was following. However, I intend to use remote modules so security was paramount. I modified Michael's answer up there so I'm posting, purely for those who spent hours looking for a secure alternative to 'require' like me. If the code is incorrect, feel free to point it out.

main.js

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

const path=require('path');
const url=require('url');

let win;

function createWindow(){
    win=new BrowserWindow({
        webPreferences:{
            contextIsolation: true,
            preload: path.join(__dirname, "preload.js")
        }
    });
    win.loadURL(url.format({
        pathname: path.join(__dirname, 'index.html'),
        protocol: 'file',
        slashes: true
    }));

    win.on('close', function(){
        win=null
    });
}

app.on('ready', createWindow);

preload.js

const electron=require('electron');
const contextBridge=electron.contextBridge;

contextBridge.exposeInMainWorld(
    "api", {
        loadscript(filename){
            require(filename);
        }
    }
);

index.html

<!DOCTYPE html>
<html>
    <head>
        <title>Hello World App</title>
    </head>
    <body>
        <h1>Hello World</h1>
        <button id="btn">Click</button>
    </body>
    <script>
        window.api.loadscript('./index.js');
    </script>
</html>

index.js

const btn = document.getElementById('btn');
btn.addEventListener('click', function(){
    console.log('button clicked');
});

I am especially curious to know if this still presents a security risk. Thanks.

Answer 8

You have to enable the in to use it. see below,

const { BrowserWindow } = require('electron')
let win = new BrowserWindow({
  webPreferences: {
    nodeIntegration: true
  }
})
win.show()

There was a breaking api changes in electron 5.0( Announcement on Repository ). In recent versions is by default set to .

Docs Due to the Node.js integration of Electron, there are some extra symbols inserted into the DOM like module, exports, require. This causes problems for some libraries since they want to insert the symbols with the same names.To solve this, you can turn off node integration in Electron:

But if you want to keep the abilities to use Node.js and Electron APIs, you have to rename the symbols in the page before including other libraries:

<head>
    <script>
        window.nodeRequire = require;
        delete window.require;
        delete window.exports;
        delete window.module;
    </script>
    <script type="text/javascript" src="jquery.js"></script>
</head>

Answer 9

If you just don't care about any security issues and want to have require being interpreted correctly by JavaScript on the browser window, then have an extra flag on the main.js code:

 webPreferences: { nodeIntegration: true, nodeIntegrationInWorker: true, nodeIntegrationInSubFrames: true, enableRemoteModule: true, contextIsolation: false //required flag } //rest of the code...

Answer 10

You could use Browserify to fix your issue, had it been a web page or a website. But since you are using Electron to render html, you just need to set node integration to true under web preference: like shown here .

Answer 11

Finally, I made it work.Add this code to your HTML document Script Element.

Sorry for the late Reply.I use the below code to do this thing.

window.nodeRequire = require;
delete window.require;
delete window.exports;
delete window.module;

And use nodeRequire instead of using require .

It works Fine.

Answer 12

you have to add the require.js dependency.

http://requirejs.org/docs/download.html