ES2015 で Python の @classmethod のように static なメソッド内で自クラスを参照するには this を使えば良い？ ref: http://qiita.com/kitsuyui/items/b7f1c5d7d969ba5febb2

file0.txt

class X(object):

    @classmethod
    def create(cls):
        return cls()


class Y(X):
    pass


x = X.create()
y = Y.create()

print(isinstance(x, X))
print(isinstance(y, X))
print(isinstance(y, Y))

file2.js

class X {
  static create() {
    return new X();
  }
}

class Y extends X {};

const x = X.create();
const y = Y.create();

console.log(x instanceof X);
console.log(y instanceof X);
console.log(y instanceof Y);

file4.js

class X {
  static create() {
    return new this();
  }
}

class Y extends X {
  static create() {
    return new Y();
  }
}

const x = X.create();
const y = Y.create();

console.log(x instanceof X);
console.log(y instanceof X);
console.log(y instanceof Y);

file6.js

class X {
  static create() {
    return new this();
  }
}

class Y extends X {};

const x = X.create();
const y = Y.create();

console.log(x instanceof X);
console.log(y instanceof X);
console.log(y instanceof Y);

実行結果

true
true
true