class类继承``` class phone{ constructor(brand,price){ this.bran

class phone{
constructor(brand,price){
this.brand=brand;
this.price=price;
}
call(){
console.log("我可以打电话");
}
}

class smartphone extends phone{
constructor(brand,price,color,size){
super(brand,price);
this.color=color;
this.size=size;
}
photo(){
console.log("拍照");
}
playgame(){
console.log("玩游戏");
}
}

const xiaomi=new smartphone('小米',888,'黑色','4.5');
console.log(xiaomi)；