小程序：实现下拉框

效果图

1，wxml代码

<viewclass='select_box'>

 <viewclass='select'catchtap='selectTap'>

  <textclass='select_text'>{{selectData[index]}}</text>

  <imageclass='select_img {{show&&"select_img_rotate"}}'src='/image/gobottom.png'></image>  

 </view>

 <viewclass='option_box'style='height:{{show?(selectData.length>5?300:selectData.length*60):0}}rpx;'>

  <textclass='option'style='{{index==selectData.length-1&&"border:0;"}}'wx:for='{{selectData}}'wx:key='this'data-index='{{index}}'catchtap='optionTap'>{{item}}</text>

 </view>

</view>

2，wxss

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;}

3，js代码

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) {

 }

})