监听页面高度，当键盘弹出时，将按钮隐藏。

data() {
  return {
    docmHeight: document.documentElement.clientHeight ||document.body.clientHeight,
    showHeight: document.documentElement.clientHeight ||document.body.clientHeight,
    hideshow:true //显示或者隐藏footer
  }
 },
watch: {
    //监听显示高度
   showHeight:function() {
     if(this.docmHeight > this.showHeight){
      //隐藏
       this.hideshow=false
     }else{
      //显示
       this.hideshow=true
     }
   }
 },
mounted() {
   //监听事件
   window.onresize = ()=>{
     return(()=>{
       this.showHeight = document.documentElement.clientHeight || document.body.clientHeight;
   })()
   }
  
 },
<div class="bottom" v-show="hideshow">
  <div class="btn">
   <button>确认</button>
   <button>取消</button>
  </div>
 </div>