微信小程序表单验证错误提示效果

<view class="ad_popError" wx:if="{{popErrorMsg}}">{{popErrorMsg}}</view> <view class="ad_popFt"> <form bindsubmit="goDetail" >   <textarea class="ad_popArea" bindinput="commentTxtFn" focus="{{isPopOpen}}" placeholder="请输入留言内容" placeholder-style="color:#cccccc;" name="textarea" />  <view class="ad_popCout">  <text class="one_star">你还可以输入</text>  <text class="one_stars {{!!tips?'danger':''}}">{{commentTxtCount}}</text>  <text class="one_star">字</text>  </view>  <button class="informBtn" form-type="submit">确认发布</button> </form> </view> 

page{background: #f4f4f4;} .ad_popHd{height: 76rpx; line-height: 76rpx; font-size: 32rpx;text-align: center; border-bottom: 1px solid #cdd1cd; padding: 0 20rpx;color: #202120;} .ad_popFt{ margin: 20rpx ; margin-top: 50rpx;} .ad_popArea{ width: 708rpx; height:400rpx;font-size:30rpx;padding: 20rpx; box-sizing: border-box; -webkit-box-sizing: border-box; line-height: 40rpx; color: #333; background: #fff; } .ad_popCout{ color: #969899; font-size: 24rpx; text-align: right; line-height: 58rpx; padding: 0 20rpx;} .informBtn{background: #09bb07;color: #fff;font-size: 34rpx; margin-top: 38rpx;height: 88rpx;} .one_stars{color: #999;} .one_star{font-size: 20rpx;color: #999;} .danger{ color: #f64400;} .ad_popError{ background: #de352d; color: #fff; height: 58rpx; line-height: 58rpx; font-size: 24rpx; text-align: center; position: absolute; left: 0; top: 0; width: 100%; z-index:3;} 

// pages/informLeaveMsg/informLeaveMsg.js Page({   /**  * 页面的初始数据  */  data: {    },  //确认发布  goDetail:function(e){  setTimeout(()=>{   var subValue = e.detail.value.textarea   console.log(subValue)   if (subValue == null || subValue == "") {   console.log("不能为空")   this.setData(    { popErrorMsg: "发布的留言内容不能为空" }   );   this.ohShitfadeOut();   return;    }    },100)    },   ohShitfadeOut() {  var fadeOutTimeout = setTimeout(() => {   this.setData({ popErrorMsg: '' });   clearTimeout(fadeOutTimeout);  }, 3000);  },  })