js 数组的处理？

Question

    let arr = [
      { areaId: 43, areaLevel: 0, areaName: "湖南" },
      { areaId: 4301, areaLevel: 1, areaName: '长沙' },
      { areaId: 430102, areaLevel: 2, areaName: '芙蓉' },
      { areaId: 430103, areaLevel: 2, areaName: '天心' },
      { areaId: 4303, areaLevel: 1, areaName: '湘潭' },
      { areaId: 430302, areaLevel: 2, areaName: '雨湖' },
      { areaId: 430304, areaLevel: 2, areaName: '岳塘' }
    ];

根据areaLevel 来过滤
想得到

    let arr = [
      { areaId: 430102, province: "湖南", city: "长沙", area: "芙蓉" },
      { areaId: 430103, province: "湖南", city: "长沙", area: "天心" },
      { areaId: 430302, province: "湖南", city: "湘潭", area: "雨湖" },
      { areaId: 430304, province: "湖南", city: "湘潭", area: "岳塘" },
    ];

麻烦各位大佬帮忙看看

Answer 1

let areanames = arr.reduce((o, item) => ((o[item.areaId] = item.areaName), o), {})
arr.filter(i => i.areaLevel == 2).map(i => {
    let areaId = i.areaId
    return {
        areaId: areaId,
        province: areanames[String(areaId).slice(0, 2)] || '',
        city: areanames[String(areaId).slice(0, 4)] || '',
        area: i.areaName
    }
})

Answer 2

console.log("结果", demo(arr))

function demo (data) {
  const nameMap = data.reduce(function (info, item) {
    info[item.areaId] = item
    return info
  }, {})

  let result = data.filter(function (item) {
    return item.areaLevel===2
  })

  result = result.map(function (item) {
    const provinceId = String(item.areaId).slice(0, 2)
    const cityId = String(item.areaId).slice(0, 4)
    return {
      areaId: item.areaId,
      province: nameMap[provinceId]?.areaName,
      city: nameMap[cityId]?.areaName,
      area: item.areaName 
    }
  })
  return result
}

Answer 3

var areaIdArray = [];
var provinceArray = [];
var cityArray = [];
for (var a = 0; a < arr.length; a++) {
    var areaObj = {}
    if (arr[a].areaLevel == 2) {
        areaObj.areaId = arr[a].areaId
        areaObj.area = arr[a].areaName
    }
    if (JSON.stringify(areaObj) != '{}') {
        areaIdArray.push(areaObj)
    }

}
for (var l = 0; l < areaIdArray.length; l++) {
    for (var al = 0; al < arr.length; al++) {
        var provincenum = String(areaIdArray[l].areaId).slice(0, 2)
        var provinceObj = {};
        var cityObj = {};
        if (arr[al].areaId == Number(provincenum)) {
            provinceObj.province = arr[al].areaName
        }
        if (JSON.stringify(provinceObj) != '{}') {
            provinceArray.push(provinceObj)
        }
        var citynum = String(areaIdArray[l].areaId).slice(0, 4)
        console.log(citynum)
        if (arr[al].areaId === Number(citynum)) {
            cityObj.city = arr[al].areaName
        }
        if (JSON.stringify(cityObj) != '{}') {
            cityArray.push(cityObj)
        }
    }
}
var areaArray = [];
for (var A = 0; A < areaIdArray.length; A++) {
    for (var P = 0; P < provinceArray.length; P++) {
        var areaObj = {}
        if (A == P) {
            areaObj.areaId = areaIdArray[A].areaId
            areaObj.province = provinceArray[P].province
            areaObj.area = areaIdArray[A].area
        }
        if (JSON.stringify(areaObj) != '{}') {
            areaArray.push(areaObj)
        }

    }
}
var arrArray = []
for (var A = 0; A < areaArray.length; A++) {
    for (var C = 0; C < cityArray.length; C++) {
        var arrObj = {}
        if (A == C) {
            arrObj.areaId = areaArray[A].areaId
            arrObj.province = areaArray[A].province
            arrObj.city = cityArray[C].city
            arrObj.area = areaArray[A].area
            console.log(arrObj)
        }
        if (JSON.stringify(arrObj) != '{}') {
            arrArray.push(arrObj)
        }

    }
}
console.log(areaArray)

Answer 4

Answer 5

let resultData = arr.filter(item =>item.areaLevel === 2).map(item => {
    let {areaName,areaLevel,...tempItem} = item;
    tempItem.area = areaName;
    return tempItem
})
arr.forEach((item,index) => {
    resultData.forEach((subitem,subindex) => {
      if(item.areaLevel === 0) {
        subitem.province = item.areaName
      }
      if(String(item.areaId) === String(subitem.areaId).slice(0,4)) {
        subitem.city = item.areaName
      }
    })
})
console.log(resultData,'resultData')