如何将省市区树结构数据扁平化转换，以便满足特定条件下的筛选要求？

function getNewData(data) {
  let d = []

  for (let province of data) {

    if (province.checked == 1) {
      let obj = {
        provinceAreald: province.code,
        cityAreald: null,  // 如2级全部选中为null
        countryAreald: null,  // 如3级全部选中为null
        actualAreaLevel: '1',
      }

      const cityArr = cityCheck(province, obj, d)

      if (cityArr.length == province.children.length) {
        Object.assign(obj, {
          cityAreald: null,
          actualAreaLevel: '1',
        })
        d.push(obj)  // 2级菜单被<全部>选中
      } else {
        d.push(...cityArr)  // 2级菜单被<部分>选中
      }

    }
  }


  function cityCheck(province, obj, d) {

    let cityArr = []
    for (let city of province.children) {

      if (city.checked == 1) {
        Object.assign(obj, {
          cityAreald: city.code,
          actualAreaLevel: '2',
        })

        // 参数obj, d可能被改变
        const countryArr = countryCheck(city, obj, d)

        if (countryArr.length == city.children.length) {
          Object.assign(obj, {
            countryAreald: null,
            actualAreaLevel: '2',
          })
          cityArr.push(obj)  // 3级菜单被<全部>选中
        } else {
          d = d.push(...countryArr)  // 3级菜单被<部分>选中
        }

      }

    }
    return cityArr

  }


  function countryCheck(city, obj, d) {

    let countryArr = []
    for (let country of city.children) {

      if (country.checked == 1) {
        countryArr.push(
          Object.assign(obj, {
            countryAreald: country.code,
            actualAreaLevel: '3',
          })
        )
      }

    }
    return countryArr
  }


  return d
}

const newData = getNewData(data)
console.log(newData)