Vue implementation of page loading animation code tutorial

<template>
 <section class="page" v-if="option" 
  :style="{background: option.background,color: option.color||&#39;#fff&#39;}"  
  :class="{&#39;page-before&#39;: option.index < currentPage,
    &#39;page-after&#39;: option.index > currentPage,
    &#39;page-current&#39;: option.index === currentPage}">
  <p :class="{&#39;all-center&#39;: option.isCenter}">
   <slot></slot>
  </p>
 </section>
 <section class="page" v-else>页面正在渲染中。。。</section>
</template>

<template>
 <nav class="controller">
  <button v-if="option.arrowsType" class="prev-btn" :class="{moving:option.arrowsType === &#39;animate&#39;}" @click="changePage(prevIndex)"></button>
  <ul v-if="option.navbar">
   <li v-for="index in pageNum" @click="changePage(index)" :class="{current:option.highlight && index === currentPage}" :key="&#39;controller-&#39;+index" :data-index="index" class="controller-item"></li>
  </ul>
  <button v-if="option.arrowsType" class="next-btn" :class="{moving:option.arrowsType === &#39;animate&#39;}" @click="changePage(nextIndex)"></button>
 </nav>
</template>

<script>
export default {
 name: &#39;page-controller&#39;,
 props: {
 pageNum: Number,
 currentPage: Number,
 option: {
  type: Object,
  default: {
  arrowsType: &#39;animate&#39;,
  navbar: true,
  highlight: true,
  loop: true  //是否开启滚动循环
  }
 }
 },
 methods: {
 changePage (index) {
  this.$emit(&#39;changePage&#39;, index);
 }
 },
 computed: {
 nextIndex () {
  if (this.currentPage === this.pageNum) {
  if(this.option.loop){
   return 1
   }else{
   return this.pageNum
   }
  } else {
  return this.currentPage + 1;
  }
 },
 prevIndex () {
  if (this.currentPage === 1) {
  if(this.option.loop){
   return this.pageNum
   }else{
   return 1
   }
  } else {
  return this.currentPage - 1;
  }
 }
 },
 created () {
 if (this.option.navbar === undefined) {
  this.option.navbar = true;
 }
 },
 mounted () {
 let _this = this;
 let timer = null;
 let start = 0;
 // 滚轮处理
 function scrollHandler (direction) {
  // 防止重复触发滚动事件
  if (timer != null) {
  return;
  }
  if (direction === &#39;down&#39;) {
  _this.changePage(_this.nextIndex);
  } else {
  _this.changePage(_this.prevIndex);
  }
  timer = setTimeout(function() {
  clearTimeout(timer);
  timer = null;
  }, 300);
 }
 // if (Object.hasOwnProperty.call(window,&#39;onmousewheel&#39;)) {
 if (Object.hasOwnProperty.call(window,&#39;onmousewheel&#39;)) {
  // 监听滚轮事件
  window.addEventListener(&#39;mousewheel&#39;,function (event) { // IE/Opera/Chrome
  let direction = event.wheelDelta > 0 ? &#39;up&#39;:&#39;down&#39;;
  scrollHandler(direction);
  },false);
 } else {
  window.addEventListener(&#39;DOMMouseScroll&#39;,function (event) { // Firefox
  let direction = event.detail > 0 ? &#39;up&#39;:&#39;down&#39;;
  scrollHandler(direction);
  },false);
 }
 // 移动端触摸事件处理
 window.addEventListener(&#39;touchstart&#39;, function (event) {
  start = event.touches[0].clientY;
 })
 window.addEventListener(&#39;touchmove&#39;, function (event) {
  event.preventDefault();
 })
 window.addEventListener(&#39;touchend&#39;, function (event) {
  let spacing = event.changedTouches[0].clientY - start;
  let direction;  
  if (spacing > 50) {
  direction = &#39;up&#39;;
  scrollHandler(direction);
  } else if (spacing < -50) {
  direction = &#39;down&#39;;
  scrollHandler(direction);
  }
 })
 }
}
</script>

<style scoped>
.controller {
 position: fixed;
 right: 20px;
 top: 50%;
 z-index: 99;
}
.controller ul {
 transform: translate3d(0,-50%,0);
 list-style: none;
 margin: 0;
 padding: 0;
}
.controller-item {
 cursor: pointer;
 width: 20px;
 height: 20px;
 border-radius: 50%;
 margin-top: 10px;
 background-color: rgba(255, 255, 255, 0.3);
 transition: background-color 0.3s ease 0s;
}
.controller-item:hover {
 background-color: rgba(255, 255, 255, 0.7);
}
.controller-item.current {
 background-color: rgba(255, 255, 255, 1);
}
.prev-btn,.next-btn {
 cursor: pointer;
 display: block;
 text-align: center;
 width: 20px;
 height: 20px;
 position: fixed;
 left: 50%;
 margin-left: -10px;
 border: 4px solid #fff;
 background-color: transparent;
 outline: none;
}
.prev-btn {
 top: 80px;
 transform: rotate(-45deg);
 border-bottom-color: transparent;
 border-left-color: transparent;
}
.next-btn {
 bottom: 80px;
 transform: rotate(45deg);
 border-top-color: transparent;
 border-left-color: transparent;
}
.prev-btn.moving {
 animation: prev-up-down 0.7s linear 0s infinite;
}
.next-btn.moving {
 animation: next-up-down 0.7s linear 0s infinite;
}
@keyframes next-up-down {
 0% {
 transform: translate3d(0,0,0) rotate(45deg);
 }
 25% {
 transform: translate3d(0,6px,0) rotate(45deg);
 }
 50% {
 transform: translate3d(0,0,0) rotate(45deg);
 }
 75% {
 transform: translate3d(0,-6px,0) rotate(45deg);
 }
 100% {
 transform: translate3d(0,0,0) rotate(45deg);
 }
}
@keyframes prev-up-down {
 0% {
 transform: translate3d(0,0,0) rotate(-45deg);
 }
 25% {
 transform: translate3d(0,-6px,0) rotate(-45deg);
 }
 50% {
 transform: translate3d(0,0,0) rotate(-45deg);
 }
 75% {
 transform: translate3d(0,6px,0) rotate(-45deg);
 }
 100% {
 transform: translate3d(0,0,0) rotate(-45deg);
 }
}
</style>