vuescroll如何实现滚动判断？

 isScrollBottom() {
   // 是否滚动到了底部
   this.box = this.$refs.chatListWrapper
   var clientHeight = this.box.clientHeight
   var scrollTop = this.box.scrollTop
   var scrollHeight = this.box.scrollHeight
   if (scrollTop + clientHeight == scrollHeight) {
    this.$store.dispatch(&＃39;setBottomBtn&＃39;, false, { root: true }) // 隐藏直达最新消息按钮
    this.isBottom = true
    this.isTop = false
   } else {
    this.$store.dispatch(&＃39;setBottomBtn&＃39;, true, { root: true }) // 显示直达最新消息按钮
    this.isTop = false
    this.isBottom = false
    if (scrollTop == 0) {
     this.isTop = true
    }
   }
  },

  getDirection() {
   // scroll滚动方向~~~~
   this.box = this.$refs.chatListWrapper
   var scrollTop = this.box.scrollTop
   var scroll = scrollTop - this.initTop
   this.initTop = scrollTop
   let dir = &＃39;down&＃39;
   if (scroll <0) {
    dir = &＃39;up&＃39;
   } else {
    dir = &＃39;down&＃39;
   }
   return dir
  },

this.fnScroll = _.throttle(() => {
}, 500)

  sendRead() {
   const chatLi = document
    .getElementById(&＃39;chat_list_wrapper&＃39;)
    .getElementsByTagName(&＃39;li&＃39;)
   var cOntainer= this.$refs.chatListWrapper
   var swHeight = container.clientHeight
   const scrollTop = container.scrollTop
   const aa = swHeight + scrollTop
   let isSeeDomArr = []
   for (let j = 0; j