<view class="commodity_screen" bindtap="hideModal" wx:if="{{showModalStatus}}"></view>
<view animation="{{animationData}}" class="commodity_attr_box" wx:if="{{showModalStatus}}"></view>

.commodity_screen {
 width: 100%;
 height: 100%;
 position: fixed;
 top: 0;
 left: 0;
 background: #000;
 opacity: 0.2;
 overflow: hidden;
 z-index: 1000;
 color: #fff;
}
.commodity_attr_box {
 width: 100%;
 overflow: hidden;
 position: fixed;
 bottom: 0;
 left: 0;
 z-index: 2000;
 background: #fff;
 padding-top: 20rpx;
}

showModal: function () {
  // 显示遮罩层
  var animation = wx.createAnimation({
   duration: 200,
   timingFunction: "linear",
   delay: 0
  })
  this.animation = animation
  animation.translateY(300).step()
  this.setData({
   animationData: animation.export(),
   showModalStatus: true
  })
  setTimeout(function () {
   animation.translateY(0).step()
   this.setData({
    animationData: animation.export()
   })
  }.bind(this), 200)
 },
 hideModal: function () {
  // 隐藏遮罩层
  var animation = wx.createAnimation({
   duration: 200,
   timingFunction: "linear",
   delay: 0
  })
  this.animation = animation
  animation.translateY(300).step()
  this.setData({
   animationData: animation.export(),
  })
  setTimeout(function () {
   animation.translateY(0).step()
   this.setData({
    animationData: animation.export(),
    showModalStatus: false
   })
  }.bind(this), 200)
 }