Class in ES6

NewClass.js

class NewClass extends DummyClass {
  constructor(variableA, variableB) {
    super(variableA, variableB);

    this.id = NewClass.defaulIdGenerator();
    this.elements = [];
    //...
  }
  update(test) {
    //...
    super.update();
  }
  static defaultIdGenerator() {
    return new DummyClass.Id();
  }
}