vue点击按钮返回页面顶部

 //返回顶部 
    <div class="backTop" v-show="topShow" @click="topBack"> Top </div>

//mounted
  window.addEventListener("scroll", this.handleScrollx, true);
    window.onscroll = () => {
      this.top = document.documentElement.scrollTop;
    };

//watch
 top(val) {
      if (val > 260) {
        this.topShow = true;
      } else {
        this.topShow = false;
      }
    },


//methods

   handleScrollx() {

      let scroolTop = window.pageYOffset;

       if (scroolTop > 50) {

         this.isShow = true;

       } else {

         this.isShow = false;

       }

     },

  topBack() {
      let time = setInterval(() => {
      this.top -= 50;
      if (this.top <= 0) {
        this.top == 0;
         document.documentElement.scrollTop = this.top;
         clearInterval(time);
       } else {
          document.documentElement.scrollTop = this.top;
         }
       }, 50);
     },