7.1、外观模式（代码）

1、typescript

interface Shape {
  draw: () => void;
}
class Rectangle implements Shape {
  draw() {
    console.log('draw Rectangle')
  }
}
class Square implements Shape {
  draw() {
    console.log('draw Square')
  }
}
class Circle implements Shape {
  draw() {
    console.log('draw Circle')
  }
}
class ShapeMaker {
  private circle: Shape;
  private rectangle: Shape;
  private square: Shape;
  constructor() {
    this.circle = new Circle();
    this.rectangle = new Rectangle();
    this.square = new Square();
  }
  drawCircle() {
    this.circle.draw();
  }
  drawRectangle() {
    this.rectangle.draw();
  }
  drawSquare() {
    this.square.draw();
  }
}
const maker = new ShapeMaker()
maker.drawCircle()
maker.drawRectangle()
maker.drawSquare()

2、javascript (apply)

这里借一下aplly方法来模拟一下

var _type = 'string'
Object.prototype.toString.apply(_type)    // "[object String]"
var _type = 123
Object.prototype.toString.apply(_type)    // "[object Number]"
var _type = null
Object.prototype.toString.apply(_type)    // "[object Null]"