How to trigger window.onerror in angular?

Question

I know there are many other posts about this topic, but I still can't get it working. I am using Angular 8 in my project and I want to send the browser console message to a server log file. Could someone please clearifiy does questions for me:

When does the window.onerror get trigged? - right know I put the function within the constructor, is that ok so? Does it get trigged, if I serve the project local?

  window.onerror = function (errorMsg, url, lineNumber) {
      alert(errorMsg + ' ' + lineNumber);
    };

What do I have to do to get it triggered? (or does for example a thrown error of a missing certificate - trigger this function?)

console.error('test') - does this trigger it?

throw new Error() - or this?

Does Console-Errors like CORS will trigger this function?
I also read that it would get triggered if an img or script source is not avilable.

app.compentent.html: <img src="test.png">

app.copmentent.ts in the constructor (the code of point one)

But I still don't get the alert to display.

I am grateful for any help - thanks

Thanks - but I already visited this site, but there I have still a view questions. Could you please give me an explation of where to use this function? (and why should I use it - what's the benefit of it?) @Jaromanda X — angularQuestions
– angularQuestions, Commented Oct 9, 2020 at 9:22
@angularQuestions look at developer.mozilla.org/en-US/docs/Web/API/Window/error_event for an explanation — Onno van der Zee
– Onno van der Zee, Commented Oct 14, 2020 at 8:30
Will the Angular's ErrorHandler also catch errors passed to window.onerror handler? I am suggesting that you will have the error within ErrorHandler.handleError(error) - so you can log that error there. — Felix
– Felix, Commented Mar 5, 2024 at 13:54

Matt · Accepted Answer · 2021-03-16 22:30:13Z

1

The following may work for you. I used it in some Vue.js code to test triggering window.onerror(). Using eval() should allow you to bypass the compile-time checks of Angular and putting it in window.onload() will ensure it is evaluated after page load.

window.onerror = function (message, source, lineno, colno, error) {
  alert('onerror called: ' + message);
}

window.onload = function () {
  eval('undefined_function()');
}

As a security note, don't use eval() in production, especially if user input could get anywhere near it.

answered Mar 16, 2021 at 22:30

Matt

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Diwakar · Accepted Answer · 2020-10-09 08:37:18Z

0

I've tried triggering error function with your code

window.onerror = function (errorMsg, url, lineNumber) {
      alert(errorMsg + ' ' + lineNumber);
    };


callingnonexistancefunction()

It is triggering while calling a non exist function.

Hope you'll get some reference

answered Oct 9, 2020 at 8:37

Diwakar

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1 Comment

angularQuestions Over a year ago

Thanks for the answer - but I still can't get it working. Because in Angular it will not compile if the function is not defined. @Diwakar So is there another way to test window.onerror function?

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