Add a button to return to the top in vue and keep reporting errors after switching pages. What's the reason?

adds a BackToTop component of the return button to the home page and listens to the scrollTop, in mounted (). If the scrollTop is greater than 0, the component is displayed, otherwise hidden. The
backToTop code is as follows:

<template>
  <span 
    tabindex="0" 
    class="iconfont" 
    title="" 
    @click="handleToTop"
    @blur="BlurOrScroll"
    ref="toTop"
  ></span>
</template>

<script>
export default {
  name: "BackToTop",
  data() {
    return {
      isToTop: false, //
      isStop: false, //
      scrollTimer: null,
      showTimer: null
    }
  },
  methods: {
    // 
    BlurOrScroll() {
      if(this.isToTop) {
        this.isStop = true;
      }
    },
    // 
    handleToTop() {
      this.isToTop = true;
      let scrollDist = 0;
      let speed = 0;
      this.scrollTimer = setInterval(() => {
        scrollDist = document.documentElement.scrollTop || document.body.scrollTop;
        speed = Math.floor(-scrollDist/6);
        if(scrollDist !== 0 && !this.isStop) {
          scrollDist = scrollDist + speed >= 0 ? scrollDist + speed : 0;
          document.documentElement.scrollTop = document.body.scrollTop = scrollDist;
        } else {
          clearInterval(this.scrollTimer);
        }
      },20);
    },
    //
    showOrHide() {
      if(this.showTimer) {
        this.showTimer = null;
      }
      this.showTimer = setInterval(() => {
        let windowH = document.documentElement.clientHeight || document.body.clientHeight;
        if(document.documentElement.scrollTop || document.body.scrollTop >= windowH) {
          this.$refs.toTop.style.display = "block";
        } else {
          this.$refs.toTop.style.display = "none";
        }
      },30);
    }
  },
  watch: {
    isStop() {
      clearInterval(this.scrollTimer);
      this.isStop = false;
    }
  },
  mounted() {
    window.addEventListener("scroll",this.showOrHide,true);
  }
}
</script>

<style lang="stylus" scoped>
  .iconfont
    display none
    position fixed
    right .5rem
    bottom 1rem
    height .6rem
    width .6rem
    font-size .8rem
    cursor pointer
    outline none
</style>

functions normally on the home page, but BackToTop keeps reporting errors after switching pages. The screenshot is as follows:

clipboard.png

there is no BackToTop component added to another page, so why did you report an error? Solve

May.31,2021

setInterval you need to use clearInterval to stop. If you don't stop, you are still in a continuous loop. The $refs.toTop after page switching is empty, and the subsequent call naturally went wrong.
saying that you need to monitor scroll is enough. Using setInterval is superfluous


that's because your scroll event monitoring is on window, so just leave the page to remove event monitoring


event monitoring is on window, and you need to perform clearInterval (this.scrollTimer) when you leave destroyed .

single page reference is just the content of the page has changed, in fact, the global variables are still there.
so your global setInterval is still running, and window 's onscroll is still running.

but your ref resources are gone. So I made a mistake

.
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b41e29-2c5af.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b41e29-2c5af.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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