使用官方(Vant Weapp - 轻量、可靠的小程序 UI 组件库)的before-close： 

wxml： 

<van-dialog use-slot title="名称" show="{{ show }}" show-cancel-button 
  bind:cancel="onClose" bind:confirm="getBackInfo" before-close="{{onBeforeClose}}">
  自定义内容
</van-dialog>

js:  

data: {
    show: false,
    onBeforeClose:''
},
getBackInfo() {
   if (this.data.XXX) {
      console.log('符合')
   } else {
      this.setData({
        show: true,
        onBeforeClose: (action) => {     
          new Promise((resolve) => {
            if (action === 'confirm') { 
              resolve(false)
            }
          })
        }
      })  
      console.log('不符合')
   }
},
onClose() {
   this.setData({
      show: false,
   });
},