//每次頁面渲染完之后滾動條在最底部
updated:function(){
 this.$nextTick(function(){
 var div = document.getElementById('dialogue_box');
 div.scrollTop = div.scrollHeight;
 })
 }

//第一次頁面渲染完之后滾動條在最底部
methods:function(){

 this.$nextTick(function(){
 var div = document.getElementById('dialogue_box');
 div.scrollTop = div.scrollHeight;
 })
 }