Automatic feedback on JavaScript error

Question

Is there a way to get an automatic feedback if an error (even syntax errors) occurs when running a JavaScript on the client side?

I was thinking of something like this:

<script src="debugger.js"></script>
<script>
    // some script with an error in it
</script>

And every time the debugger notices an error it sends a feedback to the server.

Answer 1

EDIT: I misunderstood your question initially, this should work:

Also note, this needs to go BEFORE any javascript that might cause errors.

window.onerror = function(msg,u,l)
{
    txt ="Error: " + msg + "\n";
    txt+="URL: " + u + "\n";
    txt+="Line: " + l + "\n\n";
    //Insert AJAX call that passes data (txt) to server-side script
    return true;
};

As for syntax errors, you're out of luck. Javascript simply dies when there's a syntax error. There's no way to handle it at all.

Answer 2

One technique is to use Ajax for Javascript error logging

Every javascript error can be trapped in the window.onerror event. We can return true or false so we can choose if the user shall see the normal javascript error dialog. This script will, in the very unlikely event of a javascript error, gather information about the error and send a httprequest to a page which will log the javascript error to the database.