WebKit issues with event.layerX and event.layerY

What's going on!?

"jQuery probably copies those properties into the jQuery object." You're exactly correct, so it sounds like you already know! :)

Hopefully jQuery will update their code to stop touching that, but at the same time WebKit should have known better than to log a deprecation warning on an event (at least in my opinion). One mousemove handler and your console explodes. :)

Here's a recent jQuery ticket: http://bugs.jquery.com/ticket/10531

UPDATE: This is fixed now if you upgrade to jQuery 1.7.

Please note that if upgrading jQuery doesn't fix the issue for you it may have something to do with used extensions / plugins as Jake stated in his answer.

http://jsperf.com/removing-event-props/2

The temporary fix is to run this code before you do any event binding via jQuery:

(function(){
    // remove layerX and layerY
    var all = $.event.props,
        len = all.length,
        res = [];
    while (len--) {
      var el = all[len];
      if (el != 'layerX' && el != 'layerY') res.push(el);
    }
    $.event.props = res;
}());

UPDATE

See the latest performance tests to find out what the fastest way is to remove the event props.

The shortest solution to this is this one-liner:

$.event.props = $.event.props.join('|').replace('layerX|layerY|', '').split('|');

The enormous amount of these messages (I just got 80000 of them while using gmail) is indeed a bug in Chrome.

You should star the issue on Chromium.

It can also be caused by Chrome extensions, so check them if the jQuery update doesn't work.

Here is another one line fix, without replacing the original instance of $.event.props (which may or may not be an array), just in case :-)

$.each(["layerX","layerY"], function(i,v) { if((i=p.indexOf(v)) > -1) $.fn.splice.call($.event.props,i,1) })

I've used this after calling any event:

$.event.props.splice($.event.props.indexOf("layerY"),1);
$.event.props.splice($.event.props.indexOf("layerX"),1);

That worked for me, I have no warning messages since I've made this patch on my code.

As well as the configuration issues listed in the other answers, this error can be triggered by a simple error in your own code: forgetting the '#' in from of a jQuery ID selector.

I had code looking like

$('datenotset_2341').click(function(){
 ....etc....
});

(missing out the # in front of the "datenotset")

As well as (obviously) failing to work, it triggered this error message in Chrome.

I ran into this issue in my own code. It turns out I was iterating over all properties on an event object as part of a debugging/inspection tool that I was using. In this particular instance I was using jQuery's $.extend to clone the object for later inspection, but I believe any of the standard iteration techniques in the various toolkits would have triggered the warning as well.

I mention it here because my initial thought of simply searching the code base for instances of layerX or layerY didn't help - the property was being referenced generically, not by name.