How to get the current scroll position in javascript?

June 2, 2022

Currently , I am working on scroll to top button features. The button showed up when it is scrollable to bottom. I want to remember the last position when the scroll to top button is clicked. So when the user click the scroll to bottom button , it will return to the last position. Is there any better idea to retrieve the current scroll position?

ScrollToTopBottom.vue

<template>
    <div v-scroll="onScroll">
      <v-btn v-if = "!isVisible"
          fab fixed bottom right color="primary" @click="toBottom">
          <v-icon>mdi-arrow-down-bold-box-outline</v-icon>
      </v-btn>

      <v-btn v-else
          fab fixed bottom right color="primary" @click="toTop">
          <v-icon>mdi-arrow-up-bold-box-outline</v-icon>
      </v-btn>
    </div>
</template>

<script>

export default{
    data () {
        return {
        isVisible: false
    }
  },
   methods: {
    onScroll () {
      this.isVisible = window.scrollY > 500
    },
    toTop () {
      window.scrollTo({
        top: 0,
        left: 0,
        behavior: 'smooth'
      }
      )
    },
    toBottom(){

      var scrollPos = window.scrollY || window.scrollTop 
      window.scrollTo({
        top: document.body.scrollHeight,
        behavior: 'smooth'
      })
    }
  }
}

</script>

>Solution :

You can save your position on top button click, then check it on bottom click:

Vue.component('scrollToTopButton', {
  template: `
    <div v-scroll="onScroll">
      <v-btn v-if="!isVisible" fab fixed bottom right color="primary" @click="toBottom">
        <v-icon>mdi-arrow-down-bold-box-outline</v-icon>
      </v-btn>
      <v-btn v-else fab fixed bottom right color="primary" @click="toTop">
        <v-icon>mdi-arrow-up-bold-box-outline</v-icon>
      </v-btn>
    </div>
  `,
  data () {
    return {
      isVisible: false,
      position: 0
    }
  },
   methods: {
    onScroll() {
      this.isVisible = window.scrollY > 50
    },
    toTop() {
      this.position = window.scrollY
      window.scrollTo({
        top: 0,
        left: 0,
        behavior: 'smooth'
      })
    },
    toBottom(){
      let pos = this.position > 0 ? this.position : document.body.scrollHeight
      window.scrollTo({
        top: pos,
        behavior: 'smooth'
      })
    }
  }
})
new Vue({
  el: "#demo",
  vuetify: new Vuetify(),
  
})

<link href="https://cdn.jsdelivr.net/npm/@mdi/font@6.x/css/materialdesignicons.min.css" rel="stylesheet">
<link href="https://cdn.jsdelivr.net/npm/vuetify@2.x/dist/vuetify.min.css" rel="stylesheet">
<script src="https://cdn.jsdelivr.net/npm/vue@2.x/dist/vue.js"></script>
<script src="https://cdn.jsdelivr.net/npm/vuetify@2.x/dist/vuetify.js"></script>
<div id="demo" >
  <v-app>
    <v-main>
      <v-container>
        <div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>a</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div><div>xxx</div>
        <scroll-to-top-button />
      </v-container>
    </v-main>
  </v-app>
</div>