[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();