Originally reported by dmethvin at: http://bugs.jquery.com/ticket/15169

 https://github.com/jquery/api.jquery.com/issues/514

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Not sure if $.animate intend to support generic object. The code below raise exception "Uncaught TypeError: Cannot use 'in' operator to search for 'opacity' in undefined"

var s = { opacity: 1 };
$(s).animate({opacity: 0}, 5000);

But it try to use $.css to set the opacity. So if I just change to other name

var s = { opacity2: 1 };
$(s).animate({opacity2: 0}, 5000);

and it works.

I guess it might be resolvable If jquery can detect if it's the html object or not. But not sure if $.animate intend to only support html object.

Issue reported for jQuery 1.11.1