ES6中class方法及super关键字

//父类
class Dad {
    constructor(x, y) {
        this.x = 5;
        this.y = 1;
        this.state = 789
    }

    static x = 521

    state1 = 666

    say() {
        console.log("父类bark");
    }
    talk = () => {
        console.log("父类talk");
    }

    static speak() {
        console.log("父类speak");
        console.log(this.state);
    }
    speak(){
        console.log("父类不会speak");
    }
}
//子类
class Child extends Dad {
    constructor() {
        super()
        this.x = 987
        this.toString = this.toString.bind(this)
    }

    state = {}

    toString() {
        return "(" + this.x + ", " + this.y + ")";
    }

    say = () => {
        super.say();
        console.log("子类bark");
        console.log(super.x);
    }

    talk = () => {
        super.talk()
        console.log("子类talk");
    }

    static speak() {
        super.speak()
        console.log("子类speak");
        console.log(super.x);
    }

}
console.log(new Child().x); // 输出987
console.log(new Child().y); // 输出1
new Child().say(); // 输出 父类bark  子类bark undefined
new Child().talk(); // 报错 super.talk is not a function
Child.speak(); // 父类speak undefined 子类speak topstudy