Vue3---封装一个轮播图组件

友友们，今天我们来使用Vue3封装一个轮播图组件

第一步：我们先来封装一个轮播图组件的通用组件：

（1）轮播图组件的结构 carousel.vue

<template>
  <div class='xtx-carousel'>
    <ul class="carousel-body">
     // 放置图片
      <li class="carousel-item fade">
        <RouterLink to="/">
          <img src="http://yjy-xiaotuxian-dev.oss-cn-beijing.aliyuncs.com/picture/2021-04-15/1ba86bcc-ae71-42a3-bc3e-37b662f7f07e.jpg" alt="">
        </RouterLink>
      </li>
    </ul>
    // 左右箭头
    <a href="javascript:;" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  class="carousel-btn prev"><i class="iconfont icon-angle-left"></i></a>
    <a href="javascript:;" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  class="carousel-btn next"><i class="iconfont icon-angle-right"></i></a>
   // 指示小圆点
     <div class="carousel-indicator">
      <span v-for="i in 5" :key="i"></span>
    </div>
  </div>
</template>

<script>
export default {
  name: 'XtxCarousel'
}
</script>
<style scoped >
.xtx-carousel{
  width: 100%;
  height: 100%;
  min-width: 300px;
  min-height: 150px;
  position: relative;
  .carousel{
    &-body {
      width: 100%;
      height: 100%;
    }
    &-item {
      width: 100%;
      height: 100%;
      position: absolute;
      left: 0;
      top: 0;
      opacity: 0;
      transition: opacity 0.5s linear;
      &.fade {
        opacity: 1;
        z-index: 1;
      }
      img {
        width: 100%;
        height: 100%;
      }
    }
    &-indicator {
      position: absolute;
      left: 0;
      bottom: 20px;
      z-index: 2;
      width: 100%;
      text-align: center;
      span {
        display: inline-block;
        width: 12px;
        height: 12px;
        background: rgba(0,0,0,0.2);
        border-radius: 50%;
        cursor: pointer;
        ~ span {
          margin-left: 12px;
        }
        &.active {
          background:  #fff;
        }
      }
    }
    &-btn {
      width: 44px;
      height: 44px;
      background: rgba(0,0,0,.2);
      color: #fff;
      border-radius: 50%;
      position: absolute;
      top: 228px;
      z-index: 2;
      text-align: center;
      line-height: 44px;
      opacity: 0;
      transition: all 0.5s;
      &.prev{
        left: 20px;
      }
      &.next{
        right: 20px;
      }
    }
  }
  &:hover {
    .carousel-btn {
      opacity: 1;
    }
  }
}
</style>

（2）然后我们全局注册轮播图插件，在index.js中

import Carousel from './carousel.vue'

export default {
  install (app) {
   app.component(Carousel.name, XtxCarousel)
  }
}

注：在Vue3中注册全局插件时，install的参数不在是vue而是app

（3）在main.js注册这个插件（导入并挂载）

import XxxUI from '@/xxx/index.js'
createApp(App)
  .use(store)
  .use(router)
  .use(XxxUI)
  .mount('#app')

这样我们就得到一个全局都可以使用的轮播图的插件了

第二步：使用轮播图插件

定义一个使用轮播图的插件：如banner.vue

<template>
  <div class="home-banner">
    <Carousel />
  </div>
</template>
<script>
export default {
  name: 'HomeBanner'
}
</script>
<style scoped >
.home-banner {
  width: 1240px;
  height: 500px;
  position: absolute;
  left: 0;
  top: 0;
  z-index: 98
}
</style>

渲染数据

在home.vue组件中，调用接口，渲染数据，并把数据通过自定义属性传给子组件，轮播组件

<template>
  <div class="home-banner">
    <XtxCarousel :sliders="sliders" />
  </div>
</template>
<script>
import { ref } from 'vue'
import { findBanner } from '@/api/home'
export default {
  name: 'HomeBanner',
  setup () {
    const sliders = ref([])
    findBanner().then(data => {
    sliders.value = data.result
   })
    return { sliders }
  }
}
</script>

在轮播组件完成数据渲染

<template>
  <div class='xtx-carousel'>
    <ul class="carousel-body">
+      <li class="carousel-item" v-for="(item,i) in sliders" :key="i" :class="{fade:index===i}">
        <RouterLink to="/">
+          <img :src="item.imgUrl" alt="">
        </RouterLink>
      </li>
    </ul>
    <a href="javascript:;" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  class="carousel-btn prev"><i class="iconfont icon-angle-left"></i></a>
    <a href="javascript:;" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  class="carousel-btn next"><i class="iconfont icon-angle-right"></i></a>
    <div class="carousel-indicator">
+      <span v-for="(item,i) in sliders" :key="i" :class="{active:index===i}"></span>
    </div>
  </div>
</template>

<script>
+import { ref } from 'vue'
export default {
  name: 'XtxCarousel',
+  props: {
+    sliders: {
+      type: Array,
+      default: () => []
+    }
+  },
+  setup () {
+    // 默认显示的图片的索引
+    const index = ref(0)
+    return { index }
+  }
}
</script>

注：fade是控制显示那张图片的，需要一个默认索引数据，渲染第一张图和激活第一个点

第三步：在轮播组件封装轮播的功能

包括：（1）自动轮播的功能

（2）鼠标进入暂停轮播，鼠标离开开启轮播

（3）点击左右按钮切换轮播图

（1）功能一：自动轮播功能：

父组件：banner组件

<template>
  <div class="home-banner">
    <!-- 轮播图组件 -->
    <!-- 在banner组件实现轮播业务 -->
    <!-- autoplay控制是否自动轮播  duration控制时间间隔-->
    <XtxCarousel :sliders="sliders" :autoplay="true" :duration="2" />
  </div>
</template>

轮播组件：利用定时器

+import { ref, watch } from 'vue'
export default {
  name: 'XtxCarousel',
  props: {
    sliders: {
      type: Array,
      default: () => []
    },
+    duration: {
+      type: Number,
+      default: 3000
+    },
+    autoPlay: {
+      type: Boolean,
+      default: false
+    }
  },
  setup (props) {
    // 默认显示的图片的索引
    const index = ref(0)
+    // 自动播放
+    let timer = null
+    const autoPlayFn = () => {
+      clearInterval(timer)
+      timer = setInterval(() => {
+        index.value++
+        if (index.value >= props.sliders.length) {
+          index.value = 0
+        }
+      }, props.duration)
+    }
+    watch(() => props.sliders, (newVal) => {
+      // 有数据&开启自动播放，才调用自动播放函数
+      if (newVal.length > 1 && props.autoPlay) {
+        index.value = 0
+        autoPlayFn()
+      }
+    }, { immediate: true })
+
    return { index }
  }
}

（2）功能二：鼠标进入暂停轮播，鼠标离开开启轮播

<template>
+ <div class="xtx-carousel" @mouseenter="stop" @mouseleave="start">
    <!-- 轮播图图片列表 -->
    <ul class="carousel-body">
      <li v-for="(item, i) in sliders" :key="item.id" class="carousel-item " :class="{ fade: index === i }">
        <RouterLink to="/">
          <img :src="item.imgUrl" alt="" />
        </RouterLink>
      </li>
    </ul>

    <!-- 左右两侧的小箭头 -->
    <a href="javascript:;" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  class="carousel-btn prev"><i class="iconfont icon-angle-left"></i></a>
    <a href="javascript:;" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  class="carousel-btn next"><i class="iconfont icon-angle-right"></i></a>
    <!-- 中间的指示器：5个小圆点 -->
    <div class="carousel-indicator">
      <span :class="{ active: index === i - 1 }" v-for="i in sliders.length" :key="i"></span>
    </div>
  </div>
</template>

<script>
import { ref, watch } from 'vue'
export default {
  name: 'XtxCarousel',
  props: {
    sliders: {
      type: Array,
      default: () => []
    },
    autoplay: {
      type: Boolean,
      default: true
    },
    duration: {
      type: Number,
      default: 2
    }
  },
  setup(props) {
    // 控制当前的索引
    const index = ref(0)
    const timer = ref(null)
    // 封装一个自动轮播的函数
    const autoplayFn = () => {
      // 防止触发多个定时任务
      clearInterval(timer.value)
      timer.value = setInterval(() => {
        index.value += 1
        if (index.value >= props.sliders.length) {
          // 超过右侧范围,从头开始
          index.value = 0
        }
      }, props.duration * 1000)
    }
    // 侦听器也可以侦听props的数据
    watch(
      () => props.sliders,
      () => {
        // 轮播图长度大于1并且标志位是放开的
        if (props.sliders.length > 1 && props.autoplay) {
          autoplayFn()
        }
      },
      { immediate: true }
    )
    // 进入控制暂停轮播
  +  const stop = () => {
  +    if (timer.value) {
  +     clearInterval(timer.value)
  +    }
    }
    // 离开开始轮播
   + const start = () => {
   +   if (props.sliders.length > 1 && props.autoplay) {
   +     autoplayFn()
   +   }
    }
    return { index, stop, start }
  }
}
</script>
<style scoped >
.xtx-carousel {
  width: 100%;
  height: 100%;
  min-width: 300px;
  min-height: 150px;
  position: relative;
  .carousel {
    &-body {
      width: 100%;
      height: 100%;
    }
    &-item {
      width: 100%;
      height: 100%;
      position: absolute;
      left: 0;
      top: 0;
      opacity: 0;
      transition: opacity 0.5s linear;
      // fade决定那张图显示
      &.fade {
        opacity: 1;
        z-index: 1;
      }
      img {
        width: 100%;
        height: 100%;
      }
    }
    &-indicator {
      position: absolute;
      left: 0;
      bottom: 20px;
      z-index: 2;
      width: 100%;
      text-align: center;
      span {
        display: inline-block;
        width: 12px;
        height: 12px;
        background: rgba(0, 0, 0, 0.2);
        border-radius: 50%;
        cursor: pointer;
        ~ span {
          margin-left: 12px;
        }
        &.active {
          background: #fff;
        }
      }
    }
    &-btn {
      width: 44px;
      height: 44px;
      background: rgba(0, 0, 0, 0.2);
      color: #fff;
      border-radius: 50%;
      position: absolute;
      top: 228px;
      z-index: 2;
      text-align: center;
      line-height: 44px;
      opacity: 0;
      transition: all 0.5s;
      &.prev {
        left: 20px;
      }
      &.next {
        right: 20px;
      }
    }
  }
  &:hover {
    .carousel-btn {
      opacity: 1;
    }
  }
}
</style>

（3）功能三：点击左右按钮切换轮播图

<template>
  <div class="xtx-carousel" @mouseenter="stop" @mouseleave="start">
    <!-- 轮播图图片列表 -->
    <ul class="carousel-body">
      <li v-for="(item, i) in sliders" :key="item.id" class="carousel-item " :class="{ fade: index === i }">
        <RouterLink to="/">
          <img :src="item.imgUrl" alt="" />
        </RouterLink>
      </li>
    </ul>

    <!-- 左右两侧的小箭头 -->
    // 上一张
  +  <a @click="toggle(-1)" href="javascript:;" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  class="carousel-btn prev"><i class="iconfont icon-angle-left"></i></a>
  + <a @click="toggle(+1)" href="javascript:;" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  class="carousel-btn next"><i class="iconfont icon-angle-right"></i></a>
    <!-- 中间的指示器：5个小圆点 -->
    <div class="carousel-indicator">
      <span :class="{ active: index === i - 1 }" v-for="i in sliders.length" :key="i"></span>
    </div>
  </div>
</template>

<script>
import { ref, watch, onUnmounted } from 'vue'
export default {
  name: 'XtxCarousel',
  props: {
    sliders: {
      type: Array,
      default: () => []
    },
    autoplay: {
      type: Boolean,
      default: true
    },
    duration: {
      type: Number,
      default: 2
    }
  },
  setup(props) {
    // 控制当前的索引
    const index = ref(0)
    const timer = ref(null)
    // 封装一个自动轮播的函数
    const autoplayFn = () => {
      // 防止触发多个定时任务
      clearInterval(timer.value)
      timer.value = setInterval(() => {
        index.value += 1
        if (index.value >= props.sliders.length) {
          // 超过右侧范围,从头开始
          index.value = 0
        }
      }, props.duration * 1000)
    }
    // 侦听器也可以侦听props的数据
    watch(
      () => props.sliders,
      () => {
        // 轮播图长度大于1并且标志位是放开的
        if (props.sliders.length > 1 && props.autoplay) {
          autoplayFn()
        }
      },
      { immediate: true }
    )
    // 进入控制暂停轮播
    const stop = () => {
      if (timer.value) {
        clearInterval(timer.value)
      }
    }
    // 离开开始轮播
    const start = () => {
      if (props.sliders.length > 1 && props.autoplay) {
        autoplayFn()
      }
    }
    // 手动切换轮播,每次移动一个
  +  const toggle = step => {
  +     index.value += step
  +    if (index.value >= props.sliders.length) {
  +     // 超出右侧范围,从左侧重新开始
  +     index.value = 0
  +     return
  +   }
  +    if (index.value < 0) {
  +      // 超出左侧范围,从右侧重新开始
  +      index.value = props.sliders.length
  +    }
  +  }
   
    return { index, stop, start, toggle }
  }
}
</script>
<style scoped >
.xtx-carousel {
  width: 100%;
  height: 100%;
  min-width: 300px;
  min-height: 150px;
  position: relative;
  .carousel {
    &-body {
      width: 100%;
      height: 100%;
    }
    &-item {
      width: 100%;
      height: 100%;
      position: absolute;
      left: 0;
      top: 0;
      opacity: 0;
      transition: opacity 0.5s linear;
      // fade决定那张图显示
      &.fade {
        opacity: 1;
        z-index: 1;
      }
      img {
        width: 100%;
        height: 100%;
      }
    }
    &-indicator {
      position: absolute;
      left: 0;
      bottom: 20px;
      z-index: 2;
      width: 100%;
      text-align: center;
      span {
        display: inline-block;
        width: 12px;
        height: 12px;
        background: rgba(0, 0, 0, 0.2);
        border-radius: 50%;
        cursor: pointer;
        ~ span {
          margin-left: 12px;
        }
        &.active {
          background: #fff;
        }
      }
    }
    &-btn {
      width: 44px;
      height: 44px;
      background: rgba(0, 0, 0, 0.2);
      color: #fff;
      border-radius: 50%;
      position: absolute;
      top: 228px;
      z-index: 2;
      text-align: center;
      line-height: 44px;
      opacity: 0;
      transition: all 0.5s;
      &.prev {
        left: 20px;
      }
      &.next {
        right: 20px;
      }
    }
  }
  &:hover {
    .carousel-btn {
      opacity: 1;
    }
  }
}
</style>

性能优化：在切换到其他组件时，销毁轮播图组件，使用onUnmounted

// 组件消耗，清理定时器
onUnmounted(() => {
    clearInterval(timer)
})

Vue3---封装一个轮播图组件

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