如何在构造函数中复制对象(而不是对象引用)

function Person(name, age) {
  this.name = name;
  this.age = age;
}

Person.prototype.clone = function() {
  return new Person(this.name, this.age);
};

var person1 = new Person('John', 25);
var person2 = person1.clone();

function Person(name, age) {
  Object.assign(this, { name, age });
}

var person1 = new Person('John', 25);
var person2 = Object.assign({}, person1);

function Person(name, age) {
  var jsonString = JSON.stringify({ name, age });
  var jsonObject = JSON.parse(jsonString);
  Object.assign(this, jsonObject);
}

var person1 = new Person('John', 25);
var person2 = JSON.parse(JSON.stringify(person1));