vue 回到顶部效果实现

 <div class="goPageTop">
    <img
      v-if="btnFlag"
      class="go-top"
      src="@/assets/images/Back_top.png"
      @click="backTop"
    />
  </div>

export default {
  name: "",
  components: {},
  props: {},
  data() {
    return {
        btnFlag:false
    };
  },
  computed: {},
  watch: {},
  created() {},
  mounted() {
    window.addEventListener("scroll", this.scrollToTop);
  },

  destroyed() {
    window.removeEventListener("scroll", this.scrollToTop);
  },
  methods: {
    backTop() {
      const that = this;
      let timer = setInterval(() => {
        let ispeed = Math.floor(-that.scrollTop / 5);
        document.documentElement.scrollTop = document.body.scrollTop =
          that.scrollTop + ispeed;
        if (that.scrollTop === 0) {
          clearInterval(timer);
        }
      }, 16);
    },

    scrollToTop() {
      const that = this;
      let scrollTop =
        window.pageYOffset ||
        document.documentElement.scrollTop ||
        document.body.scrollTop;
      that.scrollTop = scrollTop;
      if (that.scrollTop > 60) {
        that.btnFlag = true;
      } else {
        that.btnFlag = false;
      }
    },
  },
};

.goPageTop img {
   40px;
  height: 40px;
  position: fixed;
  right: 10px;
  bottom: 60px;
  z-index: 9;
}