vue scroll滚动判断的实现(是否滚动到底部、滚动方向、滚动节流、获取滚动区域dom元素)

 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('setBottomBtn', false, { root: true }) // 隐藏直达最新消息按钮
    this.isBottom = true
    this.isTop = false
   } else {
    this.$store.dispatch('setBottomBtn', 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 = 'down'
   if (scroll < 0) {
    dir = 'up'
   } else {
    dir = 'down'
   }
   return dir
  },

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

  sendRead() {
   const chatLi = document
    .getElementById('chat_list_wrapper')
    .getElementsByTagName('li')
   var container = this.$refs.chatListWrapper
   var swHeight = container.clientHeight
   const scrollTop = container.scrollTop
   const aa = swHeight + scrollTop
   let isSeeDomArr = []
   for (let j = 0; j < chatLi.length; j++) {
    if (scrollTop < chatLi[j].offsetTop && chatLi[j].offsetTop < aa) {
     isSeeDomArr.push(chatLi[j]) //将可视区域内所有dom存储到isSeeDomArr
    }
   }
   if (isSeeDomArr.length) {
    // 非 ceo接诊台更新消息的已读状态
    if (this.$route.path.indexOf('diagnose/ceo') === -1) {
     for (let m = 0; m < isSeeDomArr.length; m++) {
      const isSelfSend = isSeeDomArr[m].getAttribute('isSelfSend')
      const msgStatus = isSeeDomArr[m].getAttribute('msgStatus')
      const msgType = isSeeDomArr[m].getAttribute('msgType')
      if (!isSelfSend && !msgStatus && msgType !== 'notice') {
       const _id = isSeeDomArr[m].getAttribute('id')
       this.sendReadApi(_id)
      }
     }
    }
    // 更新聊天对应的咨询轨迹
    this.setCurrentFdAsk(
     isSeeDomArr[isSeeDomArr.length - 1].getAttribute('fdAsk')
    )
   }
  },