[jQuery] Deep $.extend() doesn't work with Date objects

[Tin]

Hi guys,
I'm trying to create a deep copy of an object with $.extend(true, {},
obj), but I've noticed that all of the dates get copied as a simple
Object with no properties.  Here's a sample code that demonstrates it:

var clone = $.extend(true, {}, {myDate:new Date()});

// clone.myDate returns {}
// clone.myDate.toString() -> [object Object]

Any ideas on why this is happening?