引用自身的Javascript对象...有什么问题吗？

var person = {
  name: "John",
  age: 30,
  sayHello: function() {
    console.log("Hello, my name is " + this.name);
  }
};

person.sayHello(); // 输出：Hello, my name is John

var calculator = {
  num1: 10,
  num2: 5,
  add: function() {
    return this.num1 + this.num2;
  },
  subtract: function() {
    return this.num1 - this.num2;
  },
  multiply: function() {
    return this.num1 * this.num2;
  },
  divide: function() {
    return this.num1 / this.num2;
  }
};

console.log(calculator.add()); // 输出：15
console.log(calculator.subtract()); // 输出：5
console.log(calculator.multiply()); // 输出：50
console.log(calculator.divide()); // 输出：2