[es6][iojs] ES6 class and its structure

classes.js

// ES6 class and structure
// iojs --es_staging classes.js

"use strict";

class A {
    constructor () {
        this.a = true;
    }
    isSuper() {
        return true;
    }
    methodA() {
        return true;
    }
}

class B extends A {
    constructor () {
        super();
        this.b = true;
    }
    isSuper() {
        return !super.isSuper();
    }
    methodB() {
        return true;
    }
}

class C {}

console.log(A);                    // function A
console.log(A.toString());         // whole class declaration
console.log(A.prototype);          // {isSuper: function, methodA: function}
console.log(new A());              // {a: true}
console.log(new A().constructor);  // function A

console.log(B);                    // function B
console.log(B.prototype);          // {isSuper: function, methodB: function}
console.log(new B());              // {a: true, b: true}
console.log(new B().constructor);  // function B

console.log();
console.log(A.prototype.constructor);     // function A
console.log(B.prototype.constructor);     // function B
console.log(B.__proto__);                 // function A
console.log(B.prototype.__proto__);       // A.prototype
console.log(new B().__proto__);           // B.prototype
console.log(new B().__proto__.__proto__); // A.prototype
console.log(A.__proto__);                 // function Empty
console.log(A.__proto__.toString());      // function Empty() {}
console.log(A.__proto__ === C.__proto__); // true

console.log();
// class compatible Object implementation (except toString())
var B2 = function B2() {
    B2.__proto__.call(this);
    this.b = true;
};
B2.__proto__ = A;
B2.prototype.__proto__ = A.prototype;
B2.prototype.isSuper = function isSuper() {
    return !B2.__proto__.prototype.isSuper.call(this);
};
B2.prototype.methodB = function methodB() {
    return true;
};

console.log(B2.prototype.constructor);     // function B2
console.log(B2.prototype);                 // {isSuper, methodB}
console.log(B2.__proto__);                 // function A
console.log(new B2());                     // {a: true, b: true}
console.log(new B2().__proto__);           // {isSuper, methodB}
console.log(new B2().__proto__.__proto__); // {isSuper, methodA}
console.log(new B2().methodA());           // true
console.log(new B2().isSuper());           // false