JS__class 入坑 chrome测试class 父子类 继承关系

class A{
    constructor(){//并非必须
        this.name="class_A";
        //console.log(this) //A {name: "class_A"} (另起一行)B {name: "class_A"} //父类子类分别执行了一次
    }
    static staticCallNameA(){
    return "name_A";
    }
    callNameA(){
    return "name_A";
    }
    static cover(){
    return "cover_A"
    }
}

class B extends A{
    constructor(){//子类可以不加
    super();//子类必须有
    //console.log(this)//B {name: "class_A"} //会直接打印
    }
    static staticCallNameB(){
    return "nameB";
    }
    callNameB(){
    return "name_B";
    }
    static cover(){
    return "cover_B"
    }
}

console.log(A.name,B.name) //A B //(类名)
console.log(A.staticCallNameA(),B.staticCallNameA()) //static子类继承父类
console.log(A.cover(),B.cover()) //cover_A cover_B //先读子类再读父类
console.log(A.staticCallNameB) //undefined //父类不具备子类特有函数
console.log(A.callNameA,B.callNameA) //undefined undefined //非static方法类不能直接调用

let a=new A(),b=new B; //加不加括号效果一样
console.log(a.name); //class_A
console.log(a.name,b.name) //class_A class_A
console.log(a.callNameA(),a.callNameB,b.callNameB(),b.callNameA()) //name_A undefined name_B name_A //说明继承关系同上