// 图片轮播类
var LoopImages = function(imgArr, container) {
  this.imagesArr = imgArr;
  this.container = container;
}

LoopImages.prototype = {
  // 创建轮播图片
  createImage() {
    console.log('LoopImages createImage function')
  },

  // 切换
  changeImage() {
    console.log('LoopImages changeImage function')
  },

  getImgLength() {
    return this.imagesArr.length;
  }
}

// 上下滑动图片轮播
var SlideLoopImages = function(imgArr, container) {
  LoopImages.call(this, imgArr, container);
}

SlideLoopImages.prototype = new LoopImages();
// 重写
SlideLoopImages.prototype.changeImage = function() {
  console.log('SlideLoopImages changeImage function');
}

var s = new SlideLoopImages(['1.png'], '#container')
s.changeImage(); // SlideLoopImages changeImage function
console.log(s.getImgLength()); // 1， 从原型对象上“共享”来的getImgLength方法