SOURCE

function A(name){
    this.name = name;
}
A.prototype.say = function(){
    console.log(this.name);
}

let a = new A('x');
a.say();

function B(name, sex){
    A.call(this, name)
    this.sex = sex;
}
Object.setPrototypeOf(B, A);
B.prototype.say1 = function(){
    console.log(this.sex);
}
B.constructor = B;

let b = new B('x', 'y');
b.say();
b.say1();

console.log(b);