Capturing JS errors in Chrome - javascript

I'm capturing js errors in the application with window.onerror, but the thing is - in Chrome if dev tools isn't opened - then the url parameter passed to onerror handler always equals to the opened url.
While if dev tools is opened - then the url points to the exact .js file the caused the js error.
How do you deal with it? Are there any workarounds?
And to be more clear - here are 2 results:
Uncaught ReferenceError: a is not defined index:122 - this was received after fetching a page
Uncaught ReferenceError: a is not defined List.js:122 - this was received after fetching the same page with dev tools opened. This is an expected result - I've put a(); call to the List.js file for testing.
UPD: this is done for functional testing (using selenium webdriver) - I want to capture js errors for further investigations.

Let's pose the following architecture:
window.addEventListener("error", handleException, false);
function handleException(I_sMsg) {
if (I_sMsg.stack) {
sMsg = I_sMsg.stack.replaceAll(getBaseURL(), "");
alert(sMsg);
} else if (I_sMsg.message) {
alert(I_sMsg.message);
}
return cancelEvent(I_sMsg);
}
Now any throw new Error("description"); will go through the first part of the if statement and have a nice stack for you to parse with the urls.
It also works for unexpected exceptions, having as a result the following message (in this case after calling the unexisting bibi() function)
After further investigation, my framework is using some kind of home made job management (as shown in the stack actually) where every single action belongs to a job.
The job execution method is the following (simplified)
try {
oTask.func.apply(oTask.obj, oTask.prms);
} catch(ex) {
handleException(ex);
return false;
}
So it means every single execution is encapsulated within this single try catch block. As you see, the exception is caught, and passed to the handler. Not the error.
I though it was working in the other file but it was because the call was encapsulated, while within the api.js file directly it was a free call not managed by the framework.

More of a something to try answer really but it might help.
Chrome recently added chrome://inspect/ to the list of handy URLs (see chrome://chrome-urls/ for the complete list). I cannot find the tweet or blog post I read about this unfortunately but I think it was within the last month. The URL works on Chrome 28 for sure.
chrome://inspect/ lists all open tabs with an inspect link which redirects back to the existing open page but also opens DevTools.
I'm thinking that the selenium test could open the site under test in one tab and in a second tab open the inspect page, follow the inspect link back to the test page but this time with DevTools open, allowing window.onerror to capture better errors.
Something like:
document.getElementsByClassName('row')[n].getElementsByTagName('a')[0].click()

Related

Cypress hljs is not defined

I wrote a simple test to visit the site https://auth0.github.io/device-flow-playground/
describe('My First Test Suite', () => {
it("should navigate to the application", () => {
cy.visit("https://auth0.github.io/device-flow-playground/");
});
})
But, I am getting this error :
The following error originated from your application code, not from Cypress.
> hljs is not defined
When Cypress detects uncaught errors originating from your application it will automatically fail the current test.
This behavior is configurable, and you can choose to turn this off by listening to the uncaught:exception event
I understand that Cypress cannot do much here, but still looking for some pointers if there's some way to fix this so the page loads correctly? I don't have much of JS experience here.
The line that is likely (not definitely) to be causing your problem is
<script src="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/9.15.6/highlight.min.js"></script>
This adds library hljs to the page.
You can see the above script tag if you open https://auth0.github.io/device-flow-playground/ in a browser (not Cypress) and look at the Elements tab in devtools.
It's difficult to know why this script is blocked, because it works ok on my machine.
Try putting this URL https://cdnjs.cloudflare.com/ajax/libs/highlight.js/9.15.6/highlight.min.js in the browser also, may give you some clues.
Is there a firewall preventing you access to the above?

JSON Parse error: Unrecognized token '!' - error caught by Sentry

The error in the title is caught by Sentry (an error tracking tool). Below is a screenshot from Sentry - showing the stack trace.
Note: the script /en_US/iab.autofill.payment.js where handleMessage is located is loaded from Facebook (link here), and I couldn't find this script in the javascript bundle, nor anything related to it. I assume it's loaded by a 3rd party script - I'm using Google Tag Manager (which is also loading Facebook Pixel), Segment (loading Hotjar and Mixpanel), and Snapchat. The error started to appear without any changes in these scripts or the services that they're sending data to.
Note 2: It seems that the error is triggered quite often, about 10-15% of the time. I tried to reproduce it but given that it's a handled error, it doesn't show in the dev console.
Any direction on where to look would be much appreciated.
I'm seeing this a lot, and it seems to be coming 100% from users using Facebook browser on iOS (I guess this is the browser you see when you're using the Facebook app).
I tried to debug this with a snippet:
<script>
window.addEventListener('message', function (e) {
console.log(e);
JSON.parse(e.data);
console.log('foo');
}, false);
</script>
This is from the library you linked. Assuming that e.data is JSON string (not e.g. an object?), without any safeguard seems to be breaking things.
The second console.log doesn't fire, so I think this is causing some unexpected behaviours in my case (buttons not reacting to clicks with js listeners etc)
I don't know if there is a workaround or a way to protect from this in Facebook embedded browser (I guess it's loaded there)
Looking forward to hear more info
i have meet that too, its because the one script facebook inject in. will postMessage(Object), but the another script will listen the message and try to JSON.parse an object ,so it will came out a error. u can use 'vconsole' lib, and add a window.addEventListener('message',(e)=>{console.log(e.data)}) and u can see that
Apparently, the issue went away after a couple of weeks without changing anything on my side.

Retrieving console errors to html

My question is different from the other posts similar to this.
AutoCAD offers developers a means of displaying a URL page inside the application. I created an intranet site for my company with the hopes that users can explore via desktop browser or their AutoCAD application.
The problem is that the browser AutoCAD uses is Chrome version 33 (currently its at 84) - there is no way to update or change the browser either.
I have no way to "inspect" or debug the site inside AutoCAD - and I've come to find out there are many difference in v84 and v33. I'm trying to diagnose errors right now but again, I have no way of accessing the console logs inside the AutoCAD Browser.
Is there a way for me to "alert" any errors that the console is trying to give me? (ie: the page can't find a script reference, there is an unexpected '.', etc...)
NOTE - my site runs great on the most updated Chrome browser (v84 on desktop browser), but some little things are not working right in v33 (in AutoCAD Browser).
If you control the website you can attach a listener on the window to listen for any unhandled exceptions. Add this before all other scripts to make sure everything is captured.
window.on('error', (e) => {
// if error is intresting, do work.
alert(e.message);
});
The handler accepts an ErrorEvent object.
NOTE - This will not capture errors that are triggered in scripts across domain. For example if you are loading google maps, and an error is triggered within that script, you will typically get a 'Script error.' and no other info. This has to do with cross origin policies. You can read more here.
If you need to specifically to capture data sent to console.error you can simply proxy the function. This may not capture anything except for code that explicitly calls console.error and is not recommended.
const error = console.error;
console.error = (...args) => {
// alert(...);
error.apply(console, args);
}

Error: Could not complete the operation due to error 8150002e

I am working on a Outlook VSTO add-in, in which I am using 'System.Windows.Forms.WebBrowser' to display the add-in functionality.
One functional requirement is to have oauth connection to cloud accounts (like OneDrive, Dropbox). When user clicks a button (e.g. 'Connect OneDrive'), we call 'window.open' in JavaScript code (ES6) with the oauth-url.
The issue which I am facing is, if user doesn't enter any credentials and close the window, and then again try to connect the cloud account (by clicking the 'Connect OneDrive'), I am getting an exception (Error: Could not complete the operation due to error 8150002e.).
I couldn't find any information about the error code '8150002e' on web.
This exception is not always present but comes around 50% of the times.
Any help would be appreciated in this.
what I have tried:
changing the windowName param every time window.open is called
having global var for window Object.
Using _blank parameter to open a new window every time.
After 5-6 times, the error comes up, after 5-6 times error goes away and auth window start coming up like before.
Opening a simple static HTML page in 'window.open' to verify if the issue has something to do with HTML page. The above issue is still present.
Resetting the System.Windows.Forms.WebBrowser programmatically.
Removing the cookies.
Instead of calling window.open from JavaScript code, we call VSTO code to open the browser window, the error is still there.
Edit: Created a minimal viable example at
https://github.com/vinay-x/SampleAddin
Code related to the issue:
SDXOLForm1.cs (navigates the browser to SamplePage.HTML hosted on localhost:8001)
SamplePage.HTML (contains a button, which calls window.open function).
The sample application has a windows form which contains a webBrowser control, which navigates to a simple HTML page which contains a button.
Had to deal with some IE11 stuff and I ran across this question. The solution I found to fix this issue is to set the window variable to null prior to calling window.open.
So for your example you have this:
function myFunction() {
window.open("https://www.w3schools.com", 'BackfliptOAuth', "width=800,height=800,center=true,useContentSize=true");
}
I modified it to this:
var win = null;
function myFunction() {
win = null;
win = window.open("https://www.w3schools.com", 'BackfliptOAuth', "width=800,height=800,center=true,useContentSize=true");
}

How do I test that Sentry is reporting errors?

I just installed Sentry for a client-side JavaScript app using the standard code snippet they provided. How do I test that it's working properly? I've tried manually throwing an error from my browser console and it didn't appear in Sentry. Is there any documentation on the right way to do this?
Verify (newer)
myUndefinedFunction();
Verifying Your Setup (older)
Sentry.captureException(new Error("This is my fake error message"));
https://docs.sentry.io/platforms/javascript/?platform=browser#verifying-your-setup
May be worth double-checking your setup (or updating) and config too.
The browser console can not be used as it is sandboxed. A simple trick is to attach the code to an HTML element like this:
<h1 onClick="throw new Error('Test')">
My Website
</h1>
And click on the heading afterwards.
This can be done in the browser inspector and so your source code doesn't have to be modified.
One way to generate an error in Sentry is to call a function that is not defined.
Note: This cannot be done in the console - it must be in the code.
Try adding this to your code (taken from the docs):
myUndefinedFunction();
If your code build doesn't allow this due to tests/linting you might be able to use:
window.myUndefinedFunction()
You should then see error in your browser console and in the Sentry dashboard.
Have a read of the Docs for more info.
Raven.captureMessage('Broken!') is a good place to start (also pulled from Sentry docs). If that fails to send, the Raven client isn't being initiated.
If you can't or don't want to use an undefined function to test Sentry is sending errors, you can also use the Debugger in Chrome's DevTools by:
Adding a breakpoint in your code e.g. for a click event handler
Trigger that event e.g. click a button
When the breakpoint hits in the console, set a function/variable that is needed for execution to undefined
Press play/continue in DevTools to then see the Error output
e.g.
1: function onClick() {
2: api.sendSomeEvent();
3: }
Add a breakpoint in the body of the onClick event handler (Line 2), trigger the event. When execution is paused: in your console enter something like api = undefined and hit enter to update the state. Then continue execution (click the play button), where you should see an error (ala api is undefined) that Sentry should then send for you.
Note: this works for any environment, though you may need to be clever with finding your events in minified code ;)

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