小程序图片懒加载较完美解决方案

<view class="content">
  <block wx:key="{{img}}" wx:for="{{img}}">
    <view class="pic-list">
      //listIndex大于item.index时，图片显示
      <image src="{{ listIndex > index ? item : '' }}" class="pic {{listIndex > index ?'Action':''}}" mode="widthFix" />
    </view>
  </block>
</view>

page {
 background: #fff;
}
.pic-list {
 width: 100vw;
 background: #efeff4;
 margin: 3vw 0;
}
.pic {
 width: 100%;
 display: block;
 opacity: 0;
 transition: opacity 0.3s linear 0.3s;
}
.Action {
 opacity: 1;
}

 onShow: function () {
    //获取屏幕尺寸
    const screenWidth = wx.getSystemInfoSync().windowWidth
    const screenHeight = wx.getSystemInfoSync().windowHeight
    this.setData({
      //获取页面初始状态图片数量，0.63为图片容器的高度值(63vw)，将代码中0.63改为你的容器对应高度
      listIndex: screenHeight / (screenWidth * 0.63),
      screenWidth: screenWidth,
      screenHeight: screenHeight
    })
  },
  // 滚动事件 
  onPageScroll(e) { 
    //滚动距离+屏幕高度换算vw倍数
    let listIndex = (e.scrollTop + this.data.screenHeight) / (this.data.screenWidth * 0.63)
    this.setData({
      listIndex: listIndex
    })
  }