javascript - 将对象数组转换为其属性的唯一组合数组

Question

我必须从对象中提取特定数据。我的代码可以工作，但我想知道是否可以通过使用 map 或过滤器等方法来改进它。

此内容不针对任何特定背景，仅用于人员培训。我也在使用 Lodash 库

function extractApi(data) {

  var arrayOfTowns = [];
  var arrayOfCityCode = [];
  var result = [];

//looping throw the expected datas (cities and postcode)
  for (var i = 0; i < data.features.length; i++) {
    arrayOfCityCode.push(_.toString(data.features[i].properties.postcode));
    arrayOfTowns.push(_.toString(data.features[i].properties.city));

//verify unique cities
    arrayOfTowns = _.uniq(arrayOfTowns);

//pushing to a new array to have the expected result format
    if (arrayOfTowns[i] != undefined && arrayOfCityCode != undefined){
      result[i] = arrayOfCityCode[i] + " " + arrayOfTowns[i]
    }      
  }

  return result

}

//example with some datas
extractApi(  {
      "type": "FeatureCollection",
      "limit": 20,
      "version": "draft",
      "licence": "ODbL 1.0",
      "attribution": "BAN",
      "features": [
        {
          "type": "Feature",
          "properties": {
            "importance": 0.6466,
            "type": "municipality",
            "adm_weight": 4,
            "postcode": "43000",
            "context": "43, Haute-Loire, Auvergne-Rhône-Alpes (Auvergne)",
            "id": "43157",
            "population": 18.8,
            "x": 769600,
            "y": 6438600,
            "name": "Le Puy-en-Velay",
            "citycode": "43157",
            "label": "Le Puy-en-Velay",
            "city": "Le Puy-en-Velay",
            "score": 0.8769636363636364
          },
          "geometry": {
            "coordinates": [
              3.883955,
              45.043141
            ],
            "type": "Point"
          }
        },
        {
          "type": "Feature",
          "properties": {
            "importance": 0.0867,
            "type": "municipality",
            "adm_weight": 1,
            "postcode": "43000",
            "context": "43, Haute-Loire, Auvergne-Rhône-Alpes (Auvergne)",
            "id": "43089",
            "population": 3.6,
            "x": 767600,
            "y": 6438900,
            "name": "Espaly-Saint-Marcel",
            "citycode": "43089",
            "label": "Espaly-Saint-Marcel",
            "city": "Espaly-Saint-Marcel",
            "score": 0.8260636363636362
          },
          "geometry": {
            "coordinates": [
              3.858597,
              45.046041
            ],
            "type": "Point"
          }
        },
      ],
      "query": "43000"
    }

 )

目标是接收所有 data.features.properties.postcode 和 data.features.properties.city 并将其推送到数组中。对于此示例，预期结果为 ["43000 Le Puy-en-Velay", "43000 Espaly-Saint-Marcel"]。结果中的城市应该是唯一的。

Answer 1

您确实可以使用.map来获得您想要的结果:

const parsedCities = data.features
    .map(f => `${f.properties.postcode} ${f.properties.city}`)
    .filter((f, i, a) => a.indexOf(f) === i); 

//["43000 Le Puy-en-Velay", "43000 Espaly-Saint-Marcel"]

您可以在 Array.prototype.map() here 上找到文档.