uniapp自定义返回事件

<template>
  <view>
    123
    <button type="default" @click="to()">返回</button>
  </view>
</template>

<script>
  export default {
    data() {
      return {
        
      }
    },
    methods: {
      to () {
        uni.showModal({
          title:"测试",
          content:'退出页面',
          showCancel:true,
          confirmText:'取消',
          confirmText:'提交',
          success: res=>{
              if(res.confirm){
                uni.navigateBack()
              }
          }
          // success: function (res) {
          //  if(res.confirm){
          //    uni.navigateBack()
          //  }
          // }
        })
      },
      back () {
        return new Promise((resolve,reject)=>{
          
        })
      }
    },
    onBackPress (event) {
      console.log(123,event)
      if(event.from === 'backbutton') {
        uni.showModal({
          title:"测试",
          content:'退出页面',
          showCancel:true,
          confirmText:'取消',
          confirmText:'提交',
          success: res=>{
              if(res.confirm){
                uni.navigateBack()
              }
          }
          // success: function (res) {
          //  if(res.confirm){
          //    uni.navigateBack()
          //  }
          // }
        })
        return true
      } else {
        return false
      }
      
    }
  }
</script>

<style>

</style>