Inside my main file, I have
const loadWorker = async () => {
const SyncWorker = await import("$lib/canvas.worker?worker");
syncWorker = new SyncWorker.default();
syncWorker?.postMessage({});
};
Then in my unmount I have
onMount(() => {
console.log("Canvas: mounted");
loadWorker();
});
Then in my canvas.worker.ts file, I have a simple
onmessage = () => {
console.log("Hello from the worker!");
};
export {};
This message prints successfully in Chrome, but in firefox all I get is
SyntaxError: import declarations may only appear at top level of a module
Is this because the worker is stored on my local system, and maybe there's a special flag to allow loading of system files as workers (as that seems it may be a security concern)? Firefox docs say that my browser should support workers.
Well, I should've read the documentation better.
service workers only work in the production build, not in development.
To test it locally, use vite preview
https://kit.svelte.dev/docs/service-workers
Or in my case, "npm run build && npm run preview" worked.
Hello stackoverflowers,
i'm a bit stuck after coming back to electron after a few years. Im trying to build an app and access the file system with it. I've read that the remote is now very disencouraged by electron. To get a list of files from the filesystem, i will need to access the main app from the renderer.
The solution everyone and electron seems to suggest is to use a preload.js with contextBridge to safely expose selected parts you need, which makes sense to me.
However, this is where i'm stuck, i can't seem it to get it to work. I can't really assure that the preload.js is correctly loaded. I've tried to add it the suggested way and even hardcoded the direct path to my file system:
mainWindow = new BrowserWindow({
webPreferences: {
preload: path.join(__dirname, 'preload.js'),
},
})
The preload.js
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld('api', {
send: (channel, data) => {
let validChannels = ['toMain']
if (validChannels.includes(channel)) {
ipcRenderer.send(channel, data)
}
},
receive: (channel, func) => {
let validChannels = ['fromMain']
if (validChannels.includes(channel)) {
ipcRenderer.on(channel, (event, ...args) => func(...args))
}
},
})
however, when i try to access the window.api object is undefined and i can't access any retrieval options.
maybe i've missunderstood something, but im stuck here.
EDIT:
I'm using
"electron": "^12.0.0",
EDIT2:
i've found it. i was calling electron using the bundled web app instead of my main.js file :facepalm: electron ./public/index.html" of course i needed to call the electron file
I am using ElectronJS in order to build a Desktop Application.
However, I would like to auto-update the changes in the code and see the result immediately.
For example, if I am creating a WebServer with express on localhost, alyways when i update the browser, i get the changes.
On the Go Live extension on VSCode, this happens automatically after CRTL + Save
Does there exist any similar functionality for electron?
My current alternative is to close the whole electron application and start it with npm start again...
Thanks.
use electron-hot-reload package get hotreload
import { mainReloader, rendererReloader } from 'electron-hot-reload';
import { app } from 'electron';
import path from 'path';
const mainFile = path.join(app.getAppPath(), 'dist', 'main.js');
const rendererFile = path.join(app.getAppPath(), 'dist', 'renderer.js');
mainReloader(mainFile, undefined, (error, path) => {
console.log("It is a main's process hook!");
});
rendererReloader(rendererFile, undefined, (error, path) => {
console.log("It is a renderer's process hook!");
});
Example project with configuration
https://github.com/valentineus/electron-hot-reload/tree/6feca4b65b78c674aea096906ecd7b46abebc36a/example/application/src
Found it on my own.
As #ShioT mentioned, this is called hot reload / live reload.
electron-reload | npm package
https://www.npmjs.com/package/electron-reload
Frontend
require('electron-reload')(__dirname);
Backend (hard reset)
const path = require('path')
require('electron-reload')(__dirname, {
// note that this path can vary
electron: path.join(__dirname, 'node_modules', '.bin', 'electron')
});
The simplest way I've found is using electron-reloader, after installation, just paste the following code at the top of the app entry file, and you're all set:
const { app } = require('electron')
app.isPackaged || require('electron-reloader')(module)
I have a reactJS application where I need to read in a large text file and use the data from the file to populate some arrays. I came across some code examples and I am trying to implement this code:
readTextFile = file => {
var rawFile = new XMLHttpRequest();
rawFile.open("GET", file, false);
rawFile.onreadystatechange = () => {
if (rawFile.readyState === 4) {
if (rawFile.status === 200 || rawFile.status == 0) {
var allText = rawFile.responseText;
console.log("allText: ", allText);
this.setState({
fundData: allText
});
}
}
};
rawFile.send(null);
};
The code is called by executing this line of code:
this.readTextFile("../text/fund_list.txt");
When I execute the application, I get the following error message:
GET http://localhost:8080/text/fund_list.txt 404 (Not Found)
This is what my application structure looks like:
The readTextFile function is in the account_balanc.js code and I am trying to read in the text file /text/fund_list.txt. The file does exist so obviously I am not referencing the file correctly but I don't know why.
I have tried this.readTextFile("../text/fund_list.txt") and this.readTextFile("./text/fund_list.txt"); but neither worked. I even tried moving fund_list.txt into the /screens folder and changing the function call to this.readTextFile("fund_list.txt"); but I still get the 404 error message.
Any ideas why?
Thank you.
I moved the fund_list.txt file into the public/text folder (after I created it) and changed the calling of the function to this.readTextFile("./text/fund_list.txt");
I saw this as a posted solution but then the post was removed (I don't know why) so I can't thank the user who posted it. But this solved my problem.
You can use webpack raw loader and directly import the .txt file into the component.
First, install raw-loader:
npm i -D raw-loader
Second, add the loader to your webpack config:
// webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.txt$/,
use: 'raw-loader'
}
]
}
}
Then, directly import .txt to your component:
import txt from './file.txt';
I'm assuming you are using Webpack as the bundler.
The reason you were getting a 404 Not Found is because you need to configure Webpack to bundle the file into the build folder the website is hosting.
Moving it to the /public folder worked because Webpack was configured to bundle all the files in the /public folder as it is usually the entry point of the project (since this is probably create-react-app).
Also the folks at create-react-app are smart and saw that if it was a .txt extension file, they would bundle them into a /text folder in the build file, just as any .jpg or .png files will bundle into a /images folder.
Note that a lot of files need a special webpack loader if you import them in project, but you can also use a webpack plugin to copy the file into your bundle and then read that programmatically as you are doing.
Therefore once you moved it to that folder your application could actually find it in the build folder -hosted in localhost:8080 !
Using HTML5 FileReader API you can easily read any file. Please have look at the following code:
function App() {
const [json, setJson] = useState("");
let fileInputRef = React.createRef();
return (
<div className="App">
<p>{json}</p>
<input
type="file"
ref={fileInputRef}
style={{ display: "none" }}
onChange={async e => {
const reader = new FileReader();
reader.onload = function() {
const text = reader.result;
setJson(text);
};
reader.readAsText(e.target.files[0]);
}}
accept=".json,application/json"
/>
<button
onClick={() => {
fileInputRef.current.click();
}}
>
Upload JSON file
</button>
</div>
);
}
Here is a working Demo
I don't have a lot of experience with pure javascript applications, I usually use a rails backend, but I would recommend focusing on just being able to hit http://localhost:8080/text/fund_list.txt in a browser and get a response. Once you solve that it looks like the javascript will do it's thing.
Try...
const file = require("../text/fund_list.txt");
Then
this.readTextFile(file);
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.
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,
}
});
});
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):
Have nodeIntegration:true enabled
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 required 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).
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();
});
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.
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
})
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>
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.
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...
You have to enable the nodeIntegration in webPreferences 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 nodeIntegration is by default set to false.
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>
For sake of actuality and completeness I am adding my piece of cake. Here is what I find important about this topic. Please keep in mind the date of this post - October 2022, the version of electron is 21.1.1.
There is an article in electron docs called Inter-Process Communication where this topic is described in a very clear way.
The following code is just a copy of the example code on that aforementioned site.
The main.js file:
const {app, BrowserWindow, ipcMain} = require('electron')
const path = require('path')
function createWindow () {
const mainWindow = new BrowserWindow({
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
ipcMain.on('set-title', (event, title) => {
const webContents = event.sender
const win = BrowserWindow.fromWebContents(webContents)
win.setTitle(title)
})
mainWindow.loadFile('index.html')
}
app.whenReady().then(() => {
createWindow()
app.on('activate', function () {
if (BrowserWindow.getAllWindows().length === 0) createWindow()
})
})
app.on('window-all-closed', function () {
if (process.platform !== 'darwin') app.quit()
})
The takeaway:
in webPreferences define only the preload script and leave all those nodeIntegration, nodeIntegrationInWorker, nodeIntegrationInSubFrames, enableRemoteModule, contextIsolation apply the defaults.
The next file is preload.js:
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld('electronAPI', {
setTitle: (title) => ipcRenderer.send('set-title', title)
})
Here the electronAPI object will be injected into the browsers context so there will be a window.electronAPI object which will have a member function called setTitle. Of course you can add whatever other properties there.
The setTitle function only calls ipcRenderer.send which is one end of the Inter-Process Communication brigde or tunnel if you like.
What you send in here falls out on the other end, which is in the main.js file, the ipcMain.on function. Here you register for the set-title event.
The example continues with the index.html file:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<!-- https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<title>Hello World!</title>
</head>
<body>
Title: <input id="title"/>
<button id="btn" type="button">Set</button>
<script src="./renderer.js"></script>
</body>
</html>
which loads the renderer.js script:
const setButton = document.getElementById('btn')
const titleInput = document.getElementById('title')
setButton.addEventListener('click', () => {
const title = titleInput.value
window.electronAPI.setTitle(title)
});
and there you can access the window.electronAPI.setTitle function, which you defined in preload.js where it sends the title into ipcRenderer and this title then falls out of ipcMain in main.js fireing an event and causing a function to run which in turn sets the application title.
So once again I want to emphasize to read the documentation. There is more about IPC with exanples. Also read the Context Isolation chapter, it is short and very clear.
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.