Get the actual Javascript Error object with window.onerror

this is now possible in some browsers.
The spec was updated to include the actual error with stacktrace as the 5th parameter.

the problem is that not every browser supports this yet, so you could do something like this:

window.onerror = function(message, filename, lineno, colno, error)
{
    if(error != null)
    {
        //handle the error with stacktrace in error.stack
    }
    else
    {
        //sadly only 'message', 'filename' and 'lineno' work here
    }
};