class

class Human {
    constructor(type = 'human') {
        this.type = type;
    }

    static isHuman(human) {
        return human instanceof Human;
    }

    breathe() {
        return 'h-a-a-a-m';
    }
}

class Hj extends Human {
    constructor(type, firstName, lastName) {
        super(type);
        this.firstName = firstName;
        this.lastName = lastName;
    }

    sayName() {
        // super.breathe();
        return `${this.firstName} ${this.lastName}`;
    }
}

const oldHj = new Hj('human', 'hyungju', 'lee');
console.log(Human.isHuman(oldHj)); // true
console.log(oldHj.breathe()); // h-a-a-a-m
console.log(oldHj.sayName()); // hyungju lee