vue 之返回顶部组件

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<template>
  <div class="floating" @click="goTop()" v-show="btnFlag">
    <a href="javascript:;">
      <em class="icon-text">回顶部</em>
    </a>
  </div>
</template>
<script>
export default {
  props: ["refEle", "backTime"],
  data() {
    return {
      btnFlag: false,
    };
  },
  mounted() {
    window.addEventListener("scroll", this.isShowBtn, true);
  },
  destroyed() {
    window.removeEventListener("scroll", this.isShowBtn, true);
  },
  methods: {
    goTop() {
      // 拿到当前 需要滚动的节点 距离顶部多少距离
      // console.log('ref节点',this.refEle,this.refEle.scrollTop);
      this.timer = setInterval(() => {
        let scrollTop = this.refEle.scrollTop;
        let ispeed = Math.floor(-scrollTop / 5);
        // console.log("速度和高度", ispeed, scrollTop);
        this.refEle.scrollTop = scrollTop + ispeed;
        if (scrollTop === 0) {
          // console.log("到0了");
          clearInterval(this.timer);
        }
      }, this.backTime);
    },
    isShowBtn() {
      let scrollTop = "";
      if (this.refEle) {
        scrollTop = this.refEle.scrollTop;
      } else {
        scrollTop =
          window.pageYOffset ||
          document.documentElement.scrollTop ||
          document.body.scrollTop;
      }

      if (scrollTop > 60) {
        this.btnFlag = true;
      } else {
        this.btnFlag = false;
      }
    },
  },
};
</script>
<style scoped>
.floating {
  width: 0.65rem;
  position: fixed;
  z-index: 1600;
  right: 0.2rem;
  bottom: 1rem;
}
.floating a {
  text-decoration: none;
  margin-bottom: 0.05rem;
  display: block;
  opacity: 0.9;
  background-color: rgb(130, 130, 130);
}
.floating a:hover {
  background-color: #33AAFF;
}
</style>

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	// 这个需要返回顶部的节点
	<main ref="selfCon></main>
    <BackTop
      class="back_top"
      :refEle="this.$refs.selfCon"
      :backTime="30"
    ></BackTop>