index.vue
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<template>
<transition :name="transitionName">
<div v-show="visible" :style="customStyle" class="back-to-ceiling" @click="backToTop">
<svg width="16" height="16" viewBox="0 0 17 17" xmlns="http://www.w3.org/2000/svg" class="Icon Icon--backToTopArrow" aria-hidden="true" style="height:16px;width:16px"><path d="M12.036 15.59a1 1 0 0 1-.997.995H5.032a.996.996 0 0 1-.997-.996V8.584H1.03c-1.1 0-1.36-.633-.578-1.416L7.33.29a1.003 1.003 0 0 1 1.412 0l6.878 6.88c.782.78.523 1.415-.58 1.415h-3.004v7.004z" /></svg>
</div>
</transition>
</template>
<script>
export default {
name: 'BackToTop',
props: {
visibilityHeight: {
type: Number,
default: 400
},
backPosition: {
type: Number,
default: 0
},
customStyle: {
type: Object,
default: function() {
return {
right: '50px',
bottom: '50px',
width: '40px',
height: '40px',
'border-radius': '4px',
'line-height': '45px',
background: '#e7eaf1'
}
}
},
transitionName: {
type: String,
default: 'fade'
}
},
data() {
return {
visible: false,
interval: null,
isMoving: false
}
},
mounted() {
window.addEventListener('scroll', this.handleScroll)
},
beforeDestroy() {
window.removeEventListener('scroll', this.handleScroll)
if (this.interval) {
clearInterval(this.interval)
}
},
methods: {
handleScroll() {
this.visible = window.pageYOffset > this.visibilityHeight
},
backToTop() {
if (this.isMoving) return
const start = window.pageYOffset
let i = 0
this.isMoving = true
this.interval = setInterval(() => {
const next = Math.floor(this.easeInOutQuad(10 * i, start, -start, 500))
if (next <= this.backPosition) {
window.scrollTo(0, this.backPosition)
clearInterval(this.interval)
this.isMoving = false
} else {
window.scrollTo(0, next)
}
i++
}, 16.7)
},
easeInOutQuad(t, b, c, d) {
if ((t /= d / 2) < 1) return c / 2 * t * t + b
return -c / 2 * (--t * (t - 2) - 1) + b
}
}
}
</script>
<style scoped>
.back-to-ceiling {
position: fixed;
display: inline-block;
text-align: center;
cursor: pointer;
}
.back-to-ceiling:hover {
background: #d5dbe7;
}
.fade-enter-active,
.fade-leave-active {
transition: opacity .5s;
}
.fade-enter,
.fade-leave-to {
opacity: 0
}
.back-to-ceiling .Icon {
fill: #9aaabf;
background: none;
}
</style>