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:

1. 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);
    };

2. 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?

3. Does Console-Errors like CORS will trigger this function?
4. 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

Answer 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.

Answer 2

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