text: const scroll = {
    isEnd: false,
    start(callback) {
      let timer = null
      callback && window.addEventListener('scroll', () => {
        if (timer) {
          clearTimeout(timer)
        }
        // 函数防抖
        timer = setTimeout(() => {
          // 浏览器向上滚动高度
          const scrollTop = document.documentElement.scrollTop
          // 文档的真实高度
          const scrollHeight = document.documentElement.scrollHeight
          // 浏览器窗口（文档）的可视高度，就是肉眼可见的那部分全屏高度
          const clientHeight = document.documentElement.clientHeight
          if (!this.isEnd && scrollHeight === scrollTop + clientHeight) {
            window.scrollTo(0, scrollTop - 100)
            // 请求数据
            callback()
          }
        }, 300)
      })
    },
    end() {
      this.isEnd = true
    }
  }
  export default scroll
  