I have the following electron code,
//main.js
const e = require("electron");
const ffi = require("ffi-napi");
const user32 = new ffi.Library("user32", {
GetKeyState: ["short", ["int32"]],
});
console.log(user32.GetKeyState(0x06) < 0);
function createWindow() {
let win = new e.BrowserWindow({
width: 800,
height: 600,
webPreferences: {
nodeIntegration: true,
},
});
win.loadFile("index.html");
}
e.app.whenReady().then(createWindow);
My main objective is to access windows.h functions inside an electron application. ffi-node seems to be working fine as a separate node application.
However, when I embed it into an electron app and run electron main.js it looks like it is running for few seconds, then it quits. No error code no nothing. When I try to remove the line const ffi = require("ffi-napi"); and corresponding method call, it seems to be working properly. I've also tried rebuilding the application via electron-builder install-app-deps and it didn't help.
I manage to fix the issue by changing code to this.
const { app, BrowserWindow } = require("electron");
const ffi = require("ffi-napi");
const user32 = new ffi.Library("user32", {
GetKeyState: ["short", ["int32"]],
});
console.log(user32.GetKeyState(0x06) < 0);
var win;
function createWindow() {
win = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
nodeIntegration: true,
},
});
win.loadFile("index.html");
}
app.on("ready", createWindow);
And npm install electron -g followed by npm link electron
Related
I have a simple electron app that opens a browser window to a url of a webpage.
I import my stuff using
const { BrowserWindow, app, MessageChannelMain } = require('electron');
I create my window on app.on("ready") using window = new BrowserWindow({ ... }); and everything works fine.
When I try to create a MessageChannelMain using const {port1, port2} = new MessageChannelMain();, I get the error:
TypeError: MessageChannelMain is not a constructor.
Full code:
function init_window(){
if ( mainWindow == null ) {
mainWindow = create_window();
load_window(); // calls mainWindow.loadURL(myURL);
const {port1, port2} = new MessageChannelMain();
port2.postMessage({ test: 21 })
port2.on('message', (event) => {
console.log('from renderer main world:', event.data)
});
port2.start();
mainWindow.webContents.postMessage('main-world-port', null, [port1])
mainWindow.on('closed', function(event) {
mainWindow = null;
});
mainWindow.webContents.on("did-fail-load", function(event) {
})
}
}
function create_window() {
return new BrowserWindow({
width: 1200,
height: 800,
darkTheme: true,
webPreferences: {
contextIsolation: true,
preload: path.join(__dirname, 'preload.js'),
},
});
}
When I console.log(MessageChannelMain); I get undefined.
At the same time, I get other errors when I try to use some electron stuff on the preload script:
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld(
'electron',
{
doThing: () => ipcRenderer.send('do-a-thing')
}
)
Here I am getting TypeError: Cannot read property 'exposeInMainWorld' of undefined
I'm building an app with React and Electron and trying to create a communication channel between the main (electron.js in my case) and renderer processes. By achieving this, I want to access the Store object created in my main process to save user preferences etc.
I have set up a preload script and provided the path in my main.js (electron.js). But when I try to access the method defined in the preload.js from the renderer like this window.electronAPI.sendData('user-data', this.state), it does not recognise the electronAPI (undefined variable electronAPI). Also the console.log in my preload.js is never shown when a window is loaded. Hence I assume the preload script never gets loaded and I don't know why. Any help is very much appreciated!
EDIT: The preload script seems to load now because the console.log gets printed. Maybe preload.js did load before too but I could not see it since I could only access the application by opening localhost:3000 in the browser. Now the app opens in a BrowserWindow. However the 'electronAPI' defined in the preload script cannot be accessed still.
Here is the code:
electron.js (main.js)
const electron = require('electron');
const path = require('path');
const {app, BrowserWindow, Menu, ipcMain} = electron;
let isDev = process.env.APP_DEV ? (process.env.APP_DEV.trim() === "true") : false;
function createWindow (){
const win = new BrowserWindow({
width: 970,
height: 600,
backgroundColor: '#0C0456',
webPreferences: {
nodeIntegration: true,
contextIsolation: true,
enableRemoteModule: false,
preload: path.join(__dirname, 'preload.js')
}
});
//if in development mode, load window from localhost:3000 otherwise build from index.html
try {
win.webContents.loadURL(isDev
? 'http://localhost:3000'
: `file://${path.join(__dirname,'../build/index.html')}`
)
} catch(e){
console.error(e)
}
win.webContents.openDevTools({"mode":"detach"});
//Remove menu
Menu.setApplicationMenu(null);
win.once('ready-to-show', () => win.show());
console.log("main window is shown");
console.log(typeof path.join(__dirname, 'preload.js'));
win.on('crashed',() => {
console.error(`The renderer process has crashed.`);
})
}
app.on( 'ready', () => {
createWindow(); // open default window
} );
ipcMain.on('user-data', (event, args)=>{
console.log(args);
});
preload.js
const {contextBridge, ipcRenderer} = require("electron");
const validChannels = ['user-data'];
console.log("this is the preload script");
contextBridge.exposeInMainWorld('electronAPI', {
sendData: (channel, data) => {
if(validChannels.includes(channel)){
ipcRenderer.send(channel, data);
}
}
})
I've been experiencing some issues with an Electron + Create React App app I'm making. It's an offline app for cost calculation, I need to persist a couple user settings, for this I used https://github.com/sindresorhus/electron-store. Like with most electron's modules, I have to import it as:
const Store = window.require("electron-store");
To avoid webpack's conflicts. By searching I found that for most people setting nodeIntegration: true when creating electron's BrowserWindow would avoid the problem, but it's not my case, I keep getting the same error.
What I've already tried:
Using plain require: It results in TypeError: fs.existsSync is not a function, and in console: Can't resolve 'worker_threads' in '...\node_modules\write-file-atomic'
Use a module to override webpack config: I used craco to set target to electron-renderer. It results in a blank page when I launch the app, with an error in devtools telling ReferenceError: require is not defined
Additional info is that I'm not using typescript but plain js so using "declare global" and such won't work
My public/electron.js file:
const electron = require("electron");
const app = electron.app;
const BrowserWindow = electron.BrowserWindow;
const path = require("path");
const isDev = require("electron-is-dev");
let mainWindow;
function createWindow() {
mainWindow = new BrowserWindow({
width: 900,
height: 680,
webPreferences: {
nodeIntegration: true
}
});
mainWindow.loadURL(
isDev
? "http://localhost:3000"
: `file://${path.join(__dirname, "../build/index.html")}`
);
mainWindow.on("closed", () => (mainWindow = null));
if (!isDev) mainWindow.setMenu(null);
}
app.on("ready", createWindow);
app.on("window-all-closed", () => {
if (process.platform !== "darwin") {
app.quit();
}
});
electron.app.allowRendererProcessReuse = true;
app.on("activate", () => {
if (mainWindow === null) {
createWindow();
}
});
You have tu create a preoload script on electron.
Create a file named preload.js on the directory where you have de electron main script, Put this code on it:
window.require = require;
Go to your electron main script and type this in the code where you create the window:
win = new BrowserWindow({
width: 1280,
height: 720,
webPreferences: {
nodeIntegration: false,
preload: __dirname + '/preload.js'
},
})
With this you will preload the script before all, this fixed the problem for me, I hope also for you.
Electron 12 changed the default setting of contextIsolation for webPreferences, as documented in their breaking changes for Electron 12. Setting it to false will allow you access to require() again, as per their notes:
In Electron 12, contextIsolation will be enabled by default. To restore the previous behavior, contextIsolation: false must be specified in WebPreferences.
We recommend having contextIsolation enabled for the security of your application.
Another implication is that require() cannot be used in the renderer process unless nodeIntegration is true and contextIsolation is false.
mainWindow = new BrowserWindow({
width: 900,
height: 680,
webPreferences: {
contextIsolation: false,
nodeIntegration: true
}
}
I have all my html handlers in a second file (b.js). They look like this:
window.onload = function () {
let btn = window.getElementById('btn');
button.addEventListener('click', fn);
}
This works fine, but I want to make a button to open another window, so I tried adding an exported method in main.js. My full main.js is below:
const {app, BrowserWindow} = require('electron');
let mainWindow;
function createWindow () {
// Create the browser window.
mainWindow = new BrowserWindow({
width: 500,
height: 300,
frame: false,
transparent: true,
resizable: false,
webPreferences: {
nodeIntegration: true,
}
});
mainWindow.setResizable(false);
mainWindow.loadFile('index.html');
mainWindow.webContents.openDevTools();
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.quit();
})
}
app.on('ready', createWindow);
module.exports = {
openMainScreen: function () {
mainWindow.loadFile("mainScreen.html");
mainWindow.resizeTo(1200, 800);
}
};
If I try to require(main.js)in b.js as I thought I should: I get this error:
Uncaught TypeError: Cannot read property 'on' of undefined
Pointing to app.on('ready'.... Looking at this post: Cannot read property 'on' of undefined in electron javascript It says the app is starting twice. How can I resolve this?
The way I fixed this was to use electrons built in IPCmain to communicate between javascript that was being rendered with the html and the main javascript that ran the app.
https://electronjs.org/docs/api/ipc-main
I have trouble with using Electron. As you can see the title, when i load remote module, it saids it is undefined. This is the code of entry js:
const electron = require('electron');
const { app, BrowserWindow, Tray, remote, ipcMain } = electron;
function initApp() { ... }
app.on('ready', () => {
initApp();
console.log(electron); // object, but no remote inside
console.log(electron.remote); // undefined
console.log(remote); // undefined
});
and i tried to follow official doc here: http://electron.atom.io/docs/api/remote/
with
const { remote } = electron;
const { BrowserWindow } = remote;
let win = new BrowserWindow({width: 800, height: 600}); // error! BrowserWindow is not a constructor blabla
...
remote.getCurrentWindow().focus();
i don't know what am i missing. any advice will very appreciate.
Update 2020, since this answer still appears at the top. For the original answer to work in current versions of Electron, you need to set enableRemoteModule when creating the window in your main process.
const myWindow = new BrowserWindow({
webPreferences: {
enableRemoteModule: true
}
});
Original answer:
remote is needed only to require other modules from inside a render process. In the main process you just get your modules directly from require('electron'). Which it looks like is done in the example just with remote unnecessarily added.
Render process:
const { remote } = require('electron');
const { BrowserWindow } = remote;
Main process:
const { BrowserWindow } = require('electron');
In electron 10.0.0, remoteModule is set false by default. So, if you want to use const {BrowserWindow, dialog } = require('electron').remote; in JavaScript file, then you must set enableRemoteModule as true in webPreferences.
const w = new BrowserWindow({
webPreferences: {
enableRemoteModule: true
}
});
link: https://github.com/electron/electron/blob/master/docs/breaking-changes.md#default-changed-enableremotemodule-defaults-to-false
The remote module was deprecated in Electron 12, and will be removed in Electron 14. It is replaced by the #electron/remote module.
// Deprecated in Electron 12:
const { BrowserWindow } = require('electron').remote
// Replace with:
const { BrowserWindow } = require('#electron/remote')
// In the main process:
require('#electron/remote/main').initialize()
remote becomes undefined sometimes in electron all you have to do is to go to your main.js and add the following object while creating a window under webPreference set enableRemoteModule: true as shown bellow then your problem will be solved
win = new BrowserWindow({
width: 700,
height: 600,
hasShadow: true,
webPreferences: {
nodeIntegration: true,
enableRemoteModule: true,
},
});
i enabled remote module, still getting
index.html:43 Uncaught TypeError: Cannot read properties of undefined (reading 'getCurrentWindow')
for
const remote = require('electron').remote;
(or)
const { remote } = require('electron');
while using
remote.getCurrentWindow().close();
i did add
webPreferences: {
nodeIntegration: true,
contextIsolation: false,
enableRemoteModule: true,
}