小程序弹出评论框，以及其遮罩效果实现

wxml：

<scroll-view scroll-y="{{isScroll}}">
    ...
      <!-- 评论框 -->
      <view class='model' wx:if="{{inputBoxShow}}">
        <!-- invisible_model view 用于点击隐藏model评论框 -->
        <view class='invisible_model' catchtap='invisible'></view>
        <view class='input-box'>
          <textarea class="textarea" placeholder="请输入你的看法" cursor-spacing="{{65}}" show-confirm-bar="{{false}}" adjust-position="{{true}}" auto-focus="{{true}}" />
          <text class='send'>发送</text>
        </view>
      </view>
    ...
</scroll-view>

wxss：

.model {
  position: fixed;
  width: 100vw;
  height: 100vh;
  top: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.4);
  z-index: 100;
}

.input-box {
  position: absolute;
  background-color: #f8f8f8;
  padding: 30rpx;
  padding-bottom: 130rpx;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 101;
}

.textarea {
  background-color: #fff;
  width: 100%;
  padding: 5rpx;
  height: 3.3em;
  font-size: 15px;
  position: static;
}

.send {
  font-size: 14px;
  margin-top: 5rpx;
  color: #09bb07;
  float: right;
  position: static;
}

.invisible_model{
  position: fixed;
  width: 100vw;
  height: 100vh;
  top: 0;
  bottom: 0;
}

js:

Page({
  data: {
    inputBoxShow: false,
    isScroll: true,
  },
  showInputBox: function () {
    this.setData({ inputBoxShow: true });
    this.setData({ isScroll: false });
  },
  invisible: function(){
    this.setData({ inputBoxShow: false });
    this.setData({ isScroll: true });
  }
})