JavaScript's classes are syntactic sugar over the inheritance model. They introduced a new way of defining object-oriented inheritance that existed in JavaScript but that new developers were not used to. They also introduced a simpler way of extending and defining an object prototype:

class Rectangle {
    constructor (w, h) {
        this.w = w;
        this.h = h;
    }
    get area () {
        return this.w * this.h;
    }
    static clone(r) {
        return new Rectangle(r.w, r.h);
    }
}

We just created a Rectangle class, with a constructor to specify dimensions and an area method, too. We also added a static method to clone a Rectangle instance.

Unlike the previous, and still possible, prototype definition, using this syntax will force a stricter development. More specifically:

• There's no hoisting, which means the class must be defined before usage
• There's no prototype redefinition