I've a problem with Electron where the app goes blank. i.e. It becomes a white screen. If I open the dev tools it displays the following message.
In ActivityMonitor I can see the number of Electron Helper processes drops from 3 to 2 when this happens. Plus it seems I'm not the only person to come across it. e.g.
Facing "Devtools was disconnected from the page. Once page is reloaded, Devtools will automatically reconnect."
Electron dying without any information, what now?
But I've yet to find an answer that helps. In scenarios where Electron crashes are there any good approaches to identifying the problem?
For context I'm loading an sdk into Electron. Originally I was using browserify to package it which worked fine. But I want to move to the SDKs npm release. This version seems to have introduced the problem (though the code should be the same).
A good bit of time has passed since I originally posted this question. I'll answer it myself in case my mistake can assist anyone.
I never got a "solution" to the original problem. At a much later date I switched across to the npm release of the sdk and it worked.
But before that time I'd hit this issue again. Luckily, by then, I'd added a logger that also wrote console to file. With it I noticed that a JavaScript syntax error caused the crash. e.g. Missing closing bracket, etc.
I suspect that's what caused my original problem. But the Chrome dev tools do the worst thing by blanking the console rather than preserve it when the tools crash.
Code I used to setup a logger
/*global window */
const winston = require('winston');
const prettyMs = require('pretty-ms');
/**
* Proxy the standard 'console' object and redirect it toward a logger.
*/
class Logger {
constructor() {
// Retain a reference to the original console
this.originalConsole = window.console;
this.timers = new Map([]);
// Configure a logger
this.logger = winston.createLogger({
level: 'info',
format: winston.format.combine(
winston.format.timestamp(),
winston.format.printf(({ level, message, timestamp }) => {
return `${timestamp} ${level}: ${message}`;
})
),
transports: [
new winston.transports.File(
{
filename: `${require('electron').remote.app.getPath('userData')}/logs/downloader.log`, // Note: require('electron').remote is undefined when I include it in the normal imports
handleExceptions: true, // Log unhandled exceptions
maxsize: 1048576, // 10 MB
maxFiles: 10
}
)
]
});
const _this = this;
// Switch out the console with a proxied version
window.console = new Proxy(this.originalConsole, {
// Override the console functions
get(target, property) {
// Leverage the identical logger functions
if (['debug', 'info', 'warn', 'error'].includes(property)) return (...parameters) => {
_this.logger[property](parameters);
// Simple approach to logging to console. Initially considered
// using a custom logger. But this is much easier to implement.
// Downside is that the format differs but I can live with that
_this.originalConsole[property](...parameters);
}
// The log function differs in logger so map it to info
if ('log' === property) return (...parameters) => {
_this.logger.info(parameters);
_this.originalConsole.info(...parameters);
}
// Re-implement the time and timeEnd functions
if ('time' === property) return (label) => _this.timers.set(label, window.performance.now());
if ('timeEnd' === property) return (label) => {
const now = window.performance.now();
if (!_this.timers.has(label)) {
_this.logger.warn(`console.timeEnd('${label}') called without preceding console.time('${label}')! Or console.timeEnd('${label}') has been called more than once.`)
}
const timeTaken = prettyMs(now - _this.timers.get(label));
_this.timers.delete(label);
const message = `${label} ${timeTaken}`;
_this.logger.info(message);
_this.originalConsole.info(message);
}
// Any non-overriden functions are passed to console
return target[property];
}
});
}
}
/**
* Calling this function switches the window.console for a proxied version.
* The proxy allows us to redirect the call to a logger.
*/
function switchConsoleToLogger() { new Logger(); } // eslint-disable-line no-unused-vars
Then in index.html I load this script first
<script src="js/logger.js"></script>
<script>switchConsoleToLogger()</script>
I had installed Google Chrome version 79.0.3945.130 (64 bit). My app was going to crash every time when I was in debug mode. I try all the solutions I found on the web but no one was useful. I downgrade to all the previous version:
78.x Crashed
77.x Crashed
75.x Not Crashed
I had to re-install the version 75.0.3770.80 (64 bit). Problem has been solved. It can be a new versions of Chrome problem. I sent feedback to Chrome assistence.
My problem was that I was not loading a page such as index.html. Once I loaded problem went away.
parentWindow = new BrowserWindow({
title: 'parent'
});
parentWindow.loadURL(`file://${__dirname}/index.html`);
parentWindow.webContents.openDevTools();
The trick to debugging a crash like this, is to enable logging, which is apparently disabled by default. This is done by setting the environment variable ELECTRON_ENABLE_LOGGING=1, as mentioned in this GitHub issue.
With that enabled, you should see something along the lines of this in the console:
You can download Google Chrome Canary. I was facing this problem on Google Chrome where DevTools was crashing every time on the same spot. On Chrome Canary the debugger doesn't crash.
I also faced the exact same problem
I was trying to require sqlite3 module from renderer side
which was causing a problem but once i removed the request it was working just fine
const {app , BrowserWindow , ipcMain, ipcRenderer } = require('electron')
const { event } = require('jquery')
const sqlite3 = require('sqlite3').verbose(); // <<== problem
I think the best way to solve this (if your code is really really small) just try to remove functions and run it over and over again eventually you can narrow it down to the core problem
It is a really tedious , dumb and not a smart way of doing it , but hey it worked
I encountered this issue, and couldn't figure out why the the DevTool was constantly disconnecting. So on a whim I launched Firefox Developer edition and identified the cause as an undefined variable with a string length property.
if ( args.length > 1 ) {
$( this ).find( "option" ).each(function () {
$( $( this ).attr( "s-group" ) ).hide();
});
$( args ).show();
}
TL;DR Firefox Developer edition can identify these kinds of problems when Chrome's DevTool fails.
After reading the comments above it is clear to me that there is a problem at least in Chrome that consists of not showing any indication of what the fault comes from. In Firefox, the program works but with a long delay.
But, as Shane Gannon said, the origin of the problem is certainly not in a browser but it is in the code: in my case, I had opened a while loop without adding the corresponding incremental, which made the loop infinite. As in the example below:
var a = 0;
while (a < 10) {
...
a ++ // this is the part I was missing;
}
Once this was corrected, the problem disappeared.
I found that upgrading to
react 17.0.2
react-dom 17.0.2
react-scripts 4.0.3
but also as react-scripts start is being used to run electron maybe its just react scripts that needs updating.
Well I nearly went crazy but with electron the main problem I realized I commented out the code to fetch (index.html)
// and load the index.html of the app.
mainWindow.loadFile('index.html');
check this side and make sure you have included it. without this the page will go black or wont load. so check your index.js to see if there's something to load your index.html file :) feel free to mail : profnird#gmail.com if you need additional help
Downgrade from Electron 11 to Electron 8.2 worked for me in Angular 11 - Electron - Typeorm -sqlite3 app.
It is not a solution as such, but it is an assumption of why the problem.
In the angular 'ngOnInit' lifecycle I put too many 'for' and 'while' loops, one inside the other, after cleaning the code and making it more compact, the problem disappeared, I think maybe because it didn't finish the processes within a time limit I hope someone finds this comment helpful. :)
I have stumbled upon the similar problem, My approach is comment out some line that I just added to see if it works. And if that is the case, those problem is at those lines of code.
for(var i = 0;i<objLen; i+3 ){
input_data.push(jsonObj[i].reading2);
input_label.push(jsonObj[i].dateTime);
}
The console works fine after i change the code to like this.
for(var i = 0;i<objLen; i=i+space ){
input_data.push(jsonObj[i].reading2);
input_label.push(jsonObj[i].dateTime);
}
Open your google dev console (Ctrl + shift + i). Then press (fn + F1) or just F1, then scroll down and click on the Restore defaults and reload.
I have a variable in my main javascript file e.g. var example = {};.
After webpack has finished its job, I find that example is now referenced as t. This presents me a problem as I am using the variable across the web project. I bind functions onto objects for example:
var example = {};
example.initialise = function () {};
Finally at the bottom of a page I may invoke this section of script e.g:
<script>example.initialise()</script>
This way of writing javascript functions is not unusual...
This is obviously a huge pain in the ass as I have no control over the minification. Moreover, it appears that webpack doesn't figure out that example.initialise = function () {}; relates to its newly minified var example (becoming)--> var t. I.e. it doesn't become t.initialise = function {}; either.
What am I supposed to do here?
I've tried using rollup as well. The same kind of variable minification happens.
The thing is, this kind of minification/obfuscation is great, particularly on the inner workings of functions where there's little cause for concern over the parameter names. But not on the top level. I do not understand why this is happening, or how to prevent it.
Any ideas?
I assume that there are ways to set the configuration of webpack. E.g. inside webpack.config.js, but my perusing of the webpack docs gives me no easy understanding of what options I can use to resolve this, like preventing property minification in some way.
In laravel-elixir-webpack-official code you can see minify() is being applied here, minify() uses UglifyJS2 and mangling is on by default.
Mangling is an optimisation that reduces names of local variables and functions usually to single-letters (this explains your example object being renamed to t). See the doc here.
I don't see any way you can customize minify() behaviour in laravel-elixir-webpack, so for now you might have to monkey patch WebpackTask.prototype.gulpTask method before using the module (not an ideal solution). See the lines I am commenting out.
const WebpackTask = require('laravel-elixir-webpack-official/dist/WebpackTask').default;
WebpackTask.prototype.gulpTask = function () {
return (
gulp
.src(this.src.path)
.pipe(this.webpack())
.on('error', this.onError())
// .pipe(jsFiles)
// .pipe(this.minify())
// .on('error', this.onError())
// .pipe(jsFiles.restore)
.pipe(this.saveAs(gulp))
.pipe(this.onSuccess())
);
};
Turns out I have been silly. I've discovered that you can prevent top level properties from being minified by binding it to window... which in hindsight is something I've always known and was stupid not to have realised sooner. D'oh!
So all that needed to be done was to change all top-level properties like var example = {}; to something like window.app.example = {}; in which app is helping to namespace and prevent and override anything set by the language itself.
I'm tyring to call the method checkCurrentDictionary() of nsIEditorSpellCheck from within an add-on. The relevant code I use is:
var editorSpellCheck = Cc["#mozilla.org/editor/editorspellchecker;1"].createInstance(Ci.nsIEditorSpellCheck);
editorSpellCheck.checkCurrentDictionary();
This immediately crashes the Fx. What is going wrong here?
So this probably has something to do with the fact that nsIEditorSpellCheck is not a scriptable interface.
Basically, a scriptable interface is one that can be used from JavaScript.
If you want to access the spell check service you can do something like:
let editor = editableElement.editor;
if (!editor) {
let win = editableElement.ownerDocument.defaultView;
editor = win.QueryInterface(Ci.nsIInterfaceRequestor).
getInterface(Ci.nsIWebNavigation).
QueryInterface(Ci.nsIInterfaceRequestor).
getInterface(Ci.nsIEditingSession).
getEditorForWindow(win);
}
if (!editor)
throw new Error("Unable to find editor for element " + editableElement);
(The above is from http://dxr.mozilla.org/mozilla-central/source/editor/AsyncSpellCheckTestHelper.jsm which is MPL).
Then you can use the InlineSpellCheck.jsm to do some crazy stuff.
I'm not sure what you want to do though, so perhaps you should ask that more specific question as a new question.
My question is in response to this article
https://developer.mozilla.org/En/How_to_check_the_security_state_of_an_XMLHTTPRequest_over_SSL
I have downloaded and configured the xulrunner the only problem I'm getting to run javascript given in the link to display it output. Using xulrunner i want to know how can i produce an output as a headerless command-line program not gui.
var httpRequest = Components.classes["#mozilla.org/xmlextr/xmlhttprequest;1"].createInstance();
// Disable alert popups on SSL error
httpRequest.mozBackgroundRequest = true;
httpRequest.open("GET", "https://developer.mozilla.org/", true);
httpRequest.onreadystatechange = function (aEvt) {
if (httpRequest.readyState == 4) {
// Print security state of request
dumpSecurityInfo(httpRequest.channel);
}
};
httpRequest.send(null);
In the above code taken from the same link i want to see the output of function on my command screen or even a writing the information to file would do.
Do i have to change something in *.xul file extension.? I'm new to using xulrunner some help would be very helpful for me.
To print something to the console you use the dump() function. If your code runs in the context of a window you will need to change browser.dom.window.dump.enabled preference to true. XPCOM components can simply call dump() without changing this preference.
I'm making a small file-browser for my own use, in Ruby, and using Qt for the view. The idea is that it'll end up on my TV, where I can use the remote to move up and down and launch files.
Everything works fine, until I'm going to move the selection using the remote. I managed to set up a D-Bus service, so I'll just call the methods using LIRC.
The code I'm using for setting up the view looks like this:
#dm = Qt::DirModel.new
#sm = Qt::ItemSelectionModel.new(#dm)
#lv = Qt::ListView.new
#lv.model = #dm
#lv.selectionModel = #sm
cwd = #dm.index(#dir)
#lv.rootIndex = cwd
And then I'm unsure how to change the selection. Think I must have tried about every setIndex, setSelection and every method sounding similar, on the DirModel, ItemSelectionModel and ListView, without any luck. I've been googling and reading through the API without finding anything.
Ideally, I would have something like "moveSelectionDown" and "moveSelectionUp" that takes care of it, and making sure it wraps around correctly. But I can't seem to find anything.
Managed to fix it through the ItemSelectionModel every view apparently has.
moving up:
curIndex = #lv.currentIndex
#lv.selectionModel.setCurrentIndex(curIndex.sibling(curIndex.row-1, 0), Qt::ItemSelectionModel::ClearAndSelect)
or adding one to move down
I think you're forgetting that you have to create the ModelIndex through your model:
#dm.index(3, 0, None)
I'd try this method (Though I'm not really sure, this deselects the other cells.)
#lv.setCurrentIndex(#dm.index(3, 0, None))
I haven't used Ruby for ages, so I'm not exactly sure there's None.