mounted () {
 this.scrollToBottom();
},
//每次页面渲染完之后滚动条在最底部
updated:function(){
 this.scrollToBottom();
},
methods:{
 scrollToBottom: function () {
  this.$nextTick(() => {
	 var container = this.$el.querySelector(".chatBox-content-demo");
  container.scrollTop = container.scrollHeight;
  })
}
}

::-webkit-scrollbar {
 width: 5px;
 height: 5px;
}
 
::-webkit-scrollbar-track-piece {
 background-color: rgba(0, 0, 0, 0.2);
 -webkit-border-radius: 6px;
}
 
::-webkit-scrollbar-thumb:vertical {
 height: 5px;
 background-color: rgba(125, 125, 125, 0.7);
 -webkit-border-radius: 6px;
}
 
::-webkit-scrollbar-thumb:horizontal {
 width: 5px;
 background-color: rgba(125, 125, 125, 0.7);
 -webkit-border-radius: 6px;
}

在created()或者mounted () 里都可以
 
mounted () {
 this.$nextTick(() => {
 this._initScroll();
 let allLi=this.$refs.chatcontheight.querySelectorAll("li");
 this.chartScroll.scrollToElement(allLi[allLi.length-1],0);
 });
},
//每次页面渲染完之后滚动条在最底部
updated:function(){
  this.$nextTick(() => {
this._initScroll();
let allLi=this.$refs.chatcontheight.querySelectorAll("li");
this.chartScroll.scrollToElement(allLi[allLi.length-1],0);
  });
},
methods:{
 _initScroll(){
this.chartScroll=new BScroll(this.$refs.chatcontheight,{
   click:true
  })
}}
 
结构
<div ref="$refs.chatcontheight" style="overflow: hidden;">
  <ul>
 <li></li>
  </ul>
</div>