小程序弹出评论框，以及其遮罩效果实现

<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>

.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;
}

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 });
}
})