设计模式：lession1 面向对象

一、继承: 能够将公用的方法抽离出来放在一块儿，进行屡次服用，节省代码量！

    1.一、建立类模式

   // 类，就是模板

class Person{
    constructor(name,age,food){
        this.name = name,
        this.age = age,
        this.food = food
    }
    eat(){
        console.log(`${this.name} love eat ${this.food}`)
    }
    speak(){
        console.log(`${this.name} say: my name is ${this.name},age is ${this.age}`)
    }
}

class Student extends Person{  //extends是继承的关键字，Student继承了Person的属性和方法
    constructor(name, age, food,grade){
        super(name, age, food), //和 Person.call(this,name, age, food) 原理同样
        this.grade = grade
    }
    study(){
        console.log(`${this.name}正在学习，别打扰！，他要参加${this.grade}考试！`)
    }
}

let zhang = new Person('zhang',21,'桃子');

zhang.eat();
zhang.speak();

let wang = new Person('wang',25,'葡萄');

wang.eat();
wang.speak();

let li = new Student('li', 23, '橘子','3年级')

li.eat();
li.speak();
li.study();

let honghong = new Student('honghong', 23, '苹果', '2年级')

honghong.eat();
honghong.speak();
honghong.study();