微信小程序实现图片懒加载的示例代码

<block wx:for="{{list}}" wx:key="">  <image class='relative width-100 mgb-20 fade_in' src='{{item.cover_url}}' mode='widthFix' style='display:none' bindload="_imgOnLoad" id='{{item.cover_url}}'></image>   <view class='tag-bg {{item.checked?"tag-bg1":""}}'></view>   <view class='tag-text fz-30 fwb'>{{item.type_name}}</view>   <image class='relative width-100 mgb-20 fade_in {{item.loaded?"":"loading-img"}}' src='{{item.loaded?item.cover_url:item.url}}' mode='widthFix'></image> </block>

//ajax请求数据onLoad: function () {  var that = this  var page = that.data.page  wx.request({   url: request_url,   data: {    'signature': signature,    'page':1,    'pageSize': 2   },   success: function (res) {    let list = res.data.content    for (var i = 0; i < list.length; i++) {     list[i].url = "../../img/771.gif" //用json的格式创建url，作为加载过度图片    }    that.setData({     list: list,    })   }  }) },//监听图片加载页面 _imgOnLoad: function (e) {  // console.log(e)  var loadedUrl = e.target.id  let that = this  let list = that.data.list  for (var i = 0; i < list.length; i++) {   if (list[i].cover_url == loadedUrl) {    list[i].loaded = true   }   that.setData({    list   })  } }