正确编写带有函数的getter和setter

用户7496931

我正在尝试使用getter和setter编写一个简单的对象，但我不确定是否该代码正确无误，在使用下划线的实例上我也有些困惑。我得到的当前错误是，menu.addDishToCourses is not a function但是控制台记录了进餐，将其属性显示为一个函数。是什么赋予了？

let menu = {
    _courses: {
        _appetizer: [],
        _main: [],
        _dessert: [],

        get appetizers() {
            return this._courses.appetizer;
        },
        set appetizers(appetizerInput) {
          this._courses.appetizer = appetizerIn;
        },

        get mains() {
            return this._courses.main;
        },
        set mains(mainsInput) {
          this._courses.main = mainsInput;
        },

        get desserts() {
            return this._courses.dessert;
        },

        set desserts(dessertsInput) {
            this._courses.deseserts = dessertInput;
        },
        get courses() {
            return {
                appetizers: this._courses.appetizer,
                mains: this._courses.main,
                desserts: this._courses.dessert,
            };
        },

        addDishToCourses(courseName, dishName, dishPrice) {
            const dish = {
                name: dishName,
                price: dishPrice,
            };
            this._courses[courseName].push(dish);
        },

        getRandomDishFromCourse(courseName) {
            const dishes = this._courses[courseName];
            const RandomIndex = Math.floor(Math.random() * dishes.length);
            return dishes[RandomIndex];
        },
        generateRandomMeal() {
            let appetizer = this.getRandomDishFromCourse('appetizer');
            let main = this.getRandomDishFromCourse('main');
            let dessert = this.getRandomDishFromCourse('dessert');
            let totalPrice = appetizer.price + main.price + dessert.price;

            return `You order and appetizer ${appetizer.name},${main.name} and a main dish ${main.price} and a dessert ${dessert.price}. Total price was $${totalProice}. `;
        },
    }
};
menu.addDishToCourses('_appetizer', 'pepperoni', 5.43);
menu.addDishToCourses('_mains', 'steak', 18.0);
menu.addDishToCourses('_dessert', 'pie', 3.5);

汤姆·O

您有范围问题。this在您的getter和setter方法中，引用的是_courses属性，而menu不是menu对象本身。

您可能想要设计menu类似于以下内容的对象：

let menu = {
  _courses: {
    _appetizer: [],
    _main: [],
    _dessert: [],
    get appetizer() {
      return this._appetizer
    },
    get main() {
      return this._main
    },
    get dessert() {
      return this._dessert
    }
  },
  get courses() {
    return {
      appetizers: this._courses.appetizer,
      main: this._courses.main,
      desserts: this._courses.dessert,
    };
  },
  addDishToCourses(courseName, dishName, dishPrice) {
    let dish = {
      name: dishName,
      price: dishPrice,
    };
    //console.log(this._courses[courseName]);
    this._courses[courseName].push(dish);
  }
};


menu.addDishToCourses('_appetizer', 'pepperoni', 5.43);
menu.addDishToCourses('_main', 'steak', 18.0);
menu.addDishToCourses('_dessert', 'pie', 3.5);
console.log(menu.courses);

就下划线命名属性而言，这只是命名私有变量的JavaScript约定（因为您将使用面向公众的getter和setter方法访问那些私有变量）。下划线实际上并没有任何作用。

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