es6-class类

1. 类的基本用法

es5造类

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

}
Person.prototype.sayName = function(){
    return this.name;
}
let p1 = new Person('小玉米',16)
console.log(p1)//{"name":"小玉米","age":16}

es6造类

class Person{
    //实例化的时候会立即被调用
    constructor(name,age){
        this.name = name;
        this.age = age;
    }
    // sayName(){
    //     return this.name;
    // }
    // sayAge(){
    //     return this.age;
    // }
}
let p2 = new Person('小玉米',16);
console.log(p2);//Person {name: "小玉米", age: 16}

// 也可以通过Object.assign()方法，一次性向类中添加多个方法
Object.assign(Person.prototype,{
     sayName(){
        return this.name;
    },
    sayAge(){
        return this.age;
    }
})
let p3 = new Person('小玉米',16);
console.log(p3);

2. 类的继承

使用extends关键字

// 父类
class Animal{
    constructor(name,age){
        this.name = name;
        this.age = age;
    }
    sayName(){
        return this.name;
    }
    sayAge(){
        return this.age;
    }
}
// 子类
class Dog extends Animal{
    constructor(name,age,color){
        super(name,age);//超类的意思，会调用父类的constructor
        //super(name,age)相当于 Animal.call(this,name,age);
        this.color = color;
    }
    sayColor(){
        return `${this.name}`
    }
    //重写父类的方法
    sayName(){
        return this.name + super.sayAge() + this.color;
    }
}

let d1 = new Dog('小黄',28,'red');
console.log(d1.sayName());//小黄28red
console.log(d1.sayColor());//小黄
console.log(d1.sayName());//小黄28red