javascript - 在 JavaScript 中映射对象

Question

为什么我无法在以下代码中映射数组/对象中的显示名称？

var data = [{
    "displayFieldName": "",
    "fieldAliases": {
      "OBJECTID": "OBJECTID"
    },
    "fields": [{
      "name": "OBJECTID",
      "type": "esriFieldTypeOID",
      "alias": "OBJECTID"
    }],
    "features": [{
        "attributes": {
          "OBJECTID": 649
        }
      },
      {
        "attributes": {
          "OBJECTID": 665
        }
      },
      {
        "attributes": {
          "OBJECTID": 762
        }
      }
    ]
  },
  {
    "displayFieldName": "",
    "fieldAliases": {
      "display": "display",
      "OBJECTID": "OBJECTID"
    },
    "geometryType": "esriGeometryPoint",
    "spatialReference": {
      "wkid": 4326,
      "latestWkid": 4326
    },
    "fields": [{
        "name": "display",
        "type": "esriFieldTypeString",
        "alias": "display",
        "length": 50
      },
      {
        "name": "OBJECTID",
        "type": "esriFieldTypeOID",
        "alias": "OBJECTID"
      }
    ],
    "features": [{
        "attributes": {
          "display": "Transformer",
          "OBJECTID": 1537
        },
        "geometry": {
          "x": -88.17602806699995,
          "y": 41.78431233100008
        }
      },
      {
        "attributes": {
          "display": "Transformer",
          "OBJECTID": 1591
        },
        "geometry": {
          "x": -88.17546081099994,
          "y": 41.783341919000065
        }
      }
    ]
  },
  {
    "displayFieldName": "",
    "fieldAliases": {
      "display": "display",
      "OBJECTID": "OBJECTID"
    },
    "geometryType": "esriGeometryPoint",
    "spatialReference": {
      "wkid": 4326,
      "latestWkid": 4326
    },
    "fields": [{
        "name": "display",
        "type": "esriFieldTypeString",
        "alias": "display",
        "length": 50
      },
      {
        "name": "OBJECTID",
        "type": "esriFieldTypeOID",
        "alias": "OBJECTID"
      }
    ],
    "features": [{
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13597
        },
        "geometry": {
          "x": -88.17599727899994,
          "y": 41.78465526100007
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13598
        },
        "geometry": {
          "x": -88.17595382899998,
          "y": 41.78455803400004
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13599
        },
        "geometry": {
          "x": -88.17582231499995,
          "y": 41.78435312600004
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13600
        },
        "geometry": {
          "x": -88.17561004899994,
          "y": 41.784005335000074
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13601
        },
        "geometry": {
          "x": -88.17557576699994,
          "y": 41.78393182000008
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13602
        },
        "geometry": {
          "x": -88.17535967199996,
          "y": 41.78352876900004
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13603
        },
        "geometry": {
          "x": -88.17534426199995,
          "y": 41.78340020400003
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13649
        },
        "geometry": {
          "x": -88.17450698899995,
          "y": 41.78350136200004
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13650
        },
        "geometry": {
          "x": -88.17435162999999,
          "y": 41.783597986000075
        }
      }
    ]
  }
];


var points1 = data.map((obj) => obj.features.attributes.display);
console.log(points1);

Answer 1

在 features 数组上使用另一个 map 。真的不清楚预期结果是什么，因为有些没有 display 并且有很多重复

var points1 = data.map((obj) => obj.features.map(({attributes})=>attributes.display || "NONE"));
console.log(points1);

<script>
var data = [{
    "displayFieldName": "",
    "fieldAliases": {
      "OBJECTID": "OBJECTID"
    },
    "fields": [{
      "name": "OBJECTID",
      "type": "esriFieldTypeOID",
      "alias": "OBJECTID"
    }],
    "features": [{
        "attributes": {
          "OBJECTID": 649
        }
      },
      {
        "attributes": {
          "OBJECTID": 665
        }
      },
      {
        "attributes": {
          "OBJECTID": 762
        }
      }
    ]
  },
  {
    "displayFieldName": "",
    "fieldAliases": {
      "display": "display",
      "OBJECTID": "OBJECTID"
    },
    "geometryType": "esriGeometryPoint",
    "spatialReference": {
      "wkid": 4326,
      "latestWkid": 4326
    },
    "fields": [{
        "name": "display",
        "type": "esriFieldTypeString",
        "alias": "display",
        "length": 50
      },
      {
        "name": "OBJECTID",
        "type": "esriFieldTypeOID",
        "alias": "OBJECTID"
      }
    ],
    "features": [{
        "attributes": {
          "display": "Transformer",
          "OBJECTID": 1537
        },
        "geometry": {
          "x": -88.17602806699995,
          "y": 41.78431233100008
        }
      },
      {
        "attributes": {
          "display": "Transformer",
          "OBJECTID": 1591
        },
        "geometry": {
          "x": -88.17546081099994,
          "y": 41.783341919000065
        }
      }
    ]
  },
  {
    "displayFieldName": "",
    "fieldAliases": {
      "display": "display",
      "OBJECTID": "OBJECTID"
    },
    "geometryType": "esriGeometryPoint",
    "spatialReference": {
      "wkid": 4326,
      "latestWkid": 4326
    },
    "fields": [{
        "name": "display",
        "type": "esriFieldTypeString",
        "alias": "display",
        "length": 50
      },
      {
        "name": "OBJECTID",
        "type": "esriFieldTypeOID",
        "alias": "OBJECTID"
      }
    ],
    "features": [{
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13597
        },
        "geometry": {
          "x": -88.17599727899994,
          "y": 41.78465526100007
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13598
        },
        "geometry": {
          "x": -88.17595382899998,
          "y": 41.78455803400004
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13599
        },
        "geometry": {
          "x": -88.17582231499995,
          "y": 41.78435312600004
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13600
        },
        "geometry": {
          "x": -88.17561004899994,
          "y": 41.784005335000074
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13601
        },
        "geometry": {
          "x": -88.17557576699994,
          "y": 41.78393182000008
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13602
        },
        "geometry": {
          "x": -88.17535967199996,
          "y": 41.78352876900004
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13603
        },
        "geometry": {
          "x": -88.17534426199995,
          "y": 41.78340020400003
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13649
        },
        "geometry": {
          "x": -88.17450698899995,
          "y": 41.78350136200004
        }
      },
      {
        "attributes": {
          "display": "Service Point",
          "OBJECTID": 13650
        },
        "geometry": {
          "x": -88.17435162999999,
          "y": 41.783597986000075
        }
      }
    ]
  }
];


</script>