In my web site, when I F12 from the browser, I see in the console (Chrome Dev Tools) the error/warning, "event.returnValue is deprecated. Please use the standard event.preventDefault() instead."
Yet I search my project for "event.returnValue" and it turns up no instances of that string.
Assuming it is some Microsoft or jQuery-written code that is causing this, should I do something about it, and if so, what?
see this ticket
http://bugs.jquery.com/ticket/14320
This seems to be happening in the latest version of Chrome. I guess you can not really do much about it but ignore it.