vue实现下拉刷新组件

实现下拉刷新组件的核心思路

下拉刷新功能通常通过监听触摸事件、滚动位置和动画效果实现。Vue中可以利用自定义指令或封装组件完成，以下为两种常见实现方式。

基于自定义指令的实现

创建指令监听触摸事件，计算下拉距离并触发回调：

Vue.directive('pull-to-refresh', {
  bind(el, binding) {
    let startY = 0
    let currentY = 0
    const refreshHeight = 50

    el.addEventListener('touchstart', e => {
      startY = e.touches[0].pageY
    }, { passive: true })

    el.addEventListener('touchmove', e => {
      currentY = e.touches[0].pageY
      const scrollTop = document.documentElement.scrollTop || document.body.scrollTop

      if (scrollTop === 0 && currentY - startY > 0) {
        e.preventDefault()
        const distance = Math.min(currentY - startY, refreshHeight * 3)
        binding.value(distance / refreshHeight)
      }
    }, { passive: false })

    el.addEventListener('touchend', () => {
      if ((currentY - startY) > refreshHeight) {
        binding.value('refresh')
      } else {
        binding.value(0)
      }
    }, { passive: true })
  }
})

使用方式：

<div v-pull-to-refresh="handleRefresh">
  <!-- 内容区域 -->
</div>

封装可复用组件方案

创建独立组件处理所有交互逻辑：

<template>
  <div class="refresh-container" @touchstart="onTouchStart" @touchmove="onTouchMove" @touchend="onTouchEnd">
    <div class="refresh-control" :style="{ transform: `translateY(${pullDistance}px)` }">
      <slot name="loading" v-if="isRefreshing">
        <!-- 自定义加载中状态 -->
      </slot>
      <slot name="pull" v-else>
        <!-- 自定义下拉提示 -->
      </slot>
    </div>
    <slot></slot>
  </div>
</template>

<script>
export default {
  data() {
    return {
      startY: 0,
      currentY: 0,
      pullDistance: 0,
      isRefreshing: false,
      maxPullDistance: 70
    }
  },
  methods: {
    onTouchStart(e) {
      if (this.isRefreshing) return
      this.startY = e.touches[0].pageY
    },
    onTouchMove(e) {
      if (this.isRefreshing) return
      this.currentY = e.touches[0].pageY
      const scrollTop = document.documentElement.scrollTop

      if (scrollTop === 0 && this.currentY - this.startY > 0) {
        this.pullDistance = Math.min(
          this.currentY - this.startY,
          this.maxPullDistance
        )
      }
    },
    onTouchEnd() {
      if (this.pullDistance > this.maxPullDistance * 0.6) {
        this.isRefreshing = true
        this.$emit('refresh')
      } else {
        this.pullDistance = 0
      }
    },
    finishRefresh() {
      this.isRefreshing = false
      this.pullDistance = 0
    }
  }
}
</script>

<style>
.refresh-container {
  position: relative;
}
.refresh-control {
  position: absolute;
  width: 100%;
  top: 0;
  left: 0;
  transition: transform 0.3s ease;
}
</style>

第三方库推荐方案

1. vue-pull-refresh
   安装：

   npm install vue-pull-refresh

   使用示例：

   <template>
     <pull-refresh @refresh="onRefresh">
       <!-- 内容区域 -->
     </pull-refresh>
   </template>
   
   <script>
   import PullRefresh from 'vue-pull-refresh'
   
   export default {
     components: { PullRefresh },
     methods: {
       onRefresh(done) {
         fetchData().then(() => done())
       }
     }
   }
   </script>

2. mescroll.js
   支持下拉刷新和上拉加载的完整解决方案：

   <template>
     <mescroll-vue ref="mescroll" @down="downCallback" @up="upCallback">
       <!-- 内容列表 -->
     </mescroll-vue>
   </template>

性能优化要点

• 使用CSS will-change属性提升动画性能：

  .refresh-control {
    will-change: transform;
  }

• 避免频繁的DOM操作，使用transform代替top定位

• 添加防抖处理快速连续触发

• 移动端注意passive事件监听器的使用