<template>

  <v-fab-transition>

      <v-btn fab="fab" small dark="dark" fixed="fixed" bottom="bottom" right="right" color="green" v-scroll="onScroll" v-show="fab" @click="toTop">

        <v-icon>keyboard_arrow_up</v-icon>
      </v-btn>
    </v-fab-transition>

  </template>

  
  <script>
  export default {
    name: 'app-fab',
  
    data: () => ({
      fab: false
    }),
  
    methods: {
      onScroll () {
        if (typeof window === 'undefined') return;
  
        const top = window.pageYOffset ||
          document.documentElement.offsetTop ||
          0;
  
        this.fab = top > 300;
      },
      toTop () {
        this.$router.push({ hash: '' });
        this.$vuetify.goTo(0);
      }
    }
  };
  </script>