微信小程序实现蒙版弹出窗功能

<view class="page">

 <button bindtap="showMask"> 弹出 </button>
 <view catchtouchmove="preventTouchMove" class="alert-mask" wx:if="{{showModal}}"></view>
 <view class="modalDlg" wx:if="{{showModal}}">
  <view class="modelTitle">我是标题</view>
  <view class="modeContent">
   我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容我是内容
  </view>
  <image class="hide-btn" bindtap="hideMask" src="./../images/tripDetailAlertHide.png"></image> 
 </view>
</view>

/ 弹窗蒙版 start /
.alert-mask {
 width: 100%;
 height: 100%;
 position: fixed;
 : 0;
 left: 0;
 background: #000;
 z-index: 9000;
 opacity: 0.7;
}

.modalDlg {
 width: 80%;
 height: 55%;
 position: fixed;
 : 45%;
 left: -1%;
 z-index: 9999;
 box-sizing: border-box;
 padding: 25rpx;
 margin: -370rpx 85rpx;
 background-color: #fff;
 border-radius: 18rpx;
 display: flex;
 flex-direction: column;
 align-items: center;
}
.modelTitle{
 font-size: 38rpx;
 margin-bottom: 20rpx;
}
.hide-btn {
 position: absolute;
 : 10rpx;
 right: 10rpx;
 width: 50rpx;
 height: 50rpx;
}

/ 弹窗蒙版 end/
js:

Page({
 data: {
  showModal: false
 },
 onLoad(o) {
 },
  showMask: function () {
  this.setData({
   showModal: true
  })
 },
 hideMask: function () {
  this.setData({
   showModal: false
  })
 },
})