javascript: how to display script errors in a popup alert?

Question

I want to display script errors in a popup alert instead of showing them in the browser console.

window.onerror = function() {
  var message = /* get error messages and put them here */;
  alert(message);
  return true;
};

Answer 1

Yes, that is the correct way.

See the reference here:

http://www.javascriptkit.com/javatutors/error2.shtml

And explanation of how to see more details of the error here:

http://www.javascriptkit.com/javatutors/error3.shtml

Their example:

window.onerror = function(msg, url, linenumber) {
    alert('Error message: '+msg+'\nURL: '+url+'\nLine Number: '+linenumber);
    return true;
}

If you wish to display a LIST of errors in a single pop-up, it's trickier.

Since the errors occue 1 by 1, you need to do the following:

• have window.onerror handler store error details in some array

• Check that array periodically - either via a timer, or on every N'th call of window.onerror handler, or both.

  When the check happens, process entire array, display contents as desired, and empty out an array

Answer 2

Have a look at The onerror event of the window object, specifically Getting additional details on an error

Answer 3

Check this out: http://www.javascriptkit.com/javatutors/error3.shtml. Looks like signature is function(message, url, linenumber).