[javascript] 对象拷贝

 Object.prototype.clone = function() {
   var copy = (this instanceof Array) ? [] : {};
   for (attr in this) {
     if (!obj.hasOwnProperty(attr)) continue;
     copy[attr] = (typeof this[i] == "object")?obj[attr].clone():obj[attr];
   }
   return copy;
 };

 a = {k1:1, k2:2, k3:3};
 b = a.clone();