Singleton Pattern & Composite Pattern

class Element {
  constructor (label) {}
  add (child) {}
  draw () {}
  print () {}
}
class UIElement extends Element {
  constructor (label) {
    super(label)
    this.label = label
    this.parent = null
    this.children = []
  }
  add (child) {
    child.parent = this
    this.children.push(child)
  }
  draw () {
    for (let i = 0; i < this.children.length; i++) {
      const child = this.children[i]
      child.print()
      child.draw()
    }
  }
  print () {
    console.log(`print ${this.constructor.name}(${this.label})`)
  }
}
class Window extends UIElement {}
class WindowForm extends UIElement {}
class Picture extends UIElement {}
class Button extends UIElement {}
class Frame extends UIElement {}
class Label extends UIElement {}
class TextBox extends UIElement {}
class PasswordBox extends UIElement {}
class Checkbox extends UIElement {}
class LinkLabel extends UIElement {}
const windowElement = new Window()
const winForm = new WindowForm('Window')
const winFormPicture = new Picture('Logo')
const winFormButtonLogin = new Button('Login')
const winFormButtonRegister = new Button('Register')
const winFormFrame = new Frame('Frame')
const frameLabelUsername = new Label('Username')
const frameTextboxUsername = new TextBox('Username Input')
const frameLabelPassword = new Label('Password')
const frameTextboxPassword = new PasswordBox('Password Input')
const frameCheckbox = new Checkbox('Checkbox')
const frameLabelRemember = new Label('Remember Username')
const frameLinkLabel = new LinkLabel('Forget Password')
windowElement.add(winForm)
winForm.add(winFormPicture)
winForm.add(winFormButtonLogin)
winForm.add(winFormButtonRegister)
winForm.add(winFormFrame)
winFormFrame.add(frameLabelUsername)
winFormFrame.add(frameTextboxUsername)
winFormFrame.add(frameLabelPassword)
winFormFrame.add(frameTextboxPassword)
winFormFrame.add(frameCheckbox)
winFormFrame.add(frameLabelRemember)
winFormFrame.add(frameLinkLabel)
windowElement.draw()