页面或元素内容滚动到底部

inputFocus(){
      //监听输入框获得焦点，判断软键盘弹起
      let bodyEle = document.documentElement || document.body;
      this.$nextTick(()=>{
        bodyEle.scrollTop = bodyEle.scrollHeight;
        setTimeout(()=>{//这个计时器是等待dom刷新后 定位完成
          this.$refs.mchat.scrollTop = this.$refs.mchat.scrollHeight;
        },500);
      });
    },