Demonstration of new organizational ES6 features.

Rectangle.js

/**
 * Import modules from other files.
 * 
 * This example assumes that Shape.js lies in the same directory as this file.
 */
import Shape from './Shape';

/**
 * Native classes which can inherit from other classes.
 */
class Rectangle extends Shape {
  
  /**
   * Static methods.
   */
  static getName() {
    return 'Rectangle';
  }
  
  /**
   * Class properties.
   */
  _width = undefined;
  _height = undefined;
  
  /**
   * Constructor with default parameters.
   */
  constructor(x = 0, y = 0, _width = 10, _height = 10) {
    super(x, y);
    // …
    this.render();
  }
  
  /**
   * Class methods.
   */
  render() {
    // …
  }
  
  /**
   * Getters and setters.
   */
  get width() { return this._width; }
  set width(val) { this._width = val; }
}

/**
 * Export modules for usage in other files.
 * 
 * This could also precede the class definition like so:
 * export default class Rectangle { … }
 */
export default Rectangle;