The Class extends keyword is used to create a child class of a parent class, which then inherits all the methods from the parent class.

<!-- html element to place output -->
<p id="my_output"></p>

// class
class car {
    constructor(brand) {
        this.car_name = brand;
    }
    present() {
        return 'I have a ' + this.car_name;
    }
}

class model extends car {
    constructor(brand, mod) {
        super(brand);
        this.model = mod;
    }
    show() {
        return this.present() + '. It is a ' + this.model + '.';
    }
}

// add to the class
my_car = new model('Maserati', 'Quattroporte');

// output to HTML element
document.getElementById('my_output').innerHTML = my_car.show();

I have a Maserati. It is a Quattroporte.

class childClass extends parentClass