WeChat-Applet implementiert Dropdown-Box (mit Code)

<view class=&#39;select_box&#39;>
    <view class=&#39;select&#39; catchtap=&#39;selectTap&#39;>
        <text class=&#39;select_text&#39;>{{selectData[index]}}</text>
        <image class=&#39;select_img {{show&&"select_img_rotate"}}&#39; src=&#39;/image/gobottom.png&#39;></image>         
    </view>
    <view class=&#39;option_box&#39; style=&#39;height:{{show?(selectData.length>5?300:selectData.length*60):0}}rpx;&#39;>
        <text class=&#39;option&#39; style=&#39;{{index==selectData.length-1&&"border:0;"}}&#39; wx:for=&#39;{{selectData}}&#39; wx:key=&#39;this&#39; data-index=&#39;{{index}}&#39; catchtap=&#39;optionTap&#39;>{{item}}</text>
    </view>
</view>
<!--
  show&&"select_img_rotate"-----给显示框右边的下拉箭头添加动画

  height:{{show?(selectData.length>5?300:selectData.length*60):0}}rpx;-----给改变下拉框高度，实现下拉框的显示隐藏，每个下拉选项的高度为60，下拉框的最大高度这里设置的是300，所以这里写成当数据长度大于5时，下拉框高度为300，反之下拉框高度为数据长度乘以60

  index==selectData.length-1&&"border:0;"-----取消下拉选项的最后一个的下边框
  -->

page{
  background: #f3f7f7;
}
.select_box{
  background: #fff;
  width: 80%;
  margin: 30rpx auto;
  position: relative;
}
.select{
  box-sizing: border-box;
  width: 100%;
  height: 70rpx;
  border:1px solid #efefef;
  border-radius: 8rpx;
  display: flex;
  align-items: center;
  padding: 0 20rpx;
}
.select_text{
  font-size: 30rpx;
  flex: 1;
}
.select_img{
  width: 40rpx;
  height: 40rpx;
  display: block;
  transition:transform 0.3s;
}
.select_img_rotate{
  transform:rotate(180deg); 
}
.option_box{
  position: absolute;
  top: 70rpx;
  width: 100%;
  border:1px solid #efefef;
  box-sizing: border-box;
  height: 0;
  overflow-y: auto;
  border-top: 0;
  background: #fff;
  transition: height 0.3s;
}
.option{
  display: block;
  line-height: 40rpx;
  font-size: 30rpx;
  border-bottom: 1px solid #efefef;
  padding: 10rpx;
}

Page({

  data: {
    show:false,//控制下拉列表的显示隐藏，false隐藏、true显示
    selectData:['1','2','3','4','5','6'],//下拉列表的数据
    index:0//选择的下拉列表下标
  },
  // 点击下拉显示框
  selectTap(){
    this.setData({
      show: !this.data.show
    });
  },
  // 点击下拉列表
  optionTap(e){
    let Index=e.currentTarget.dataset.index;//获取点击的下拉列表的下标
    this.setData({
      index:Index,
      show:!this.data.show
    });
  },
  onLoad: function (options) {
  
  }

})