如何将“ for”循环的结果保存到单个变量中？ （JavaScript）Node.js

Question

我有一个像这样的数组：

  var polygons = [
  {
    "_id" : "12345",
    "geometry" : {
       "coordinates" : [[
           [9.123553, 48.71568],
           [ 9.119548, 48.71526 ]
       ]]
    }
  },
  {
    "_id" : "67890",
    "geometry" : {
       "coordinates" : [[
           [ 9.090445, 48.715736 ],
           [ 9.089583, 48.715687 ]
       ]]
    }
  }
]

我需要在一个变量中输入以下结果：

[
  { 
    "_id" : "12345",
    "coordinates" : [[
      [9.123553, 48.71568],
      [ 9.119548, 48.71526 ]  
    ]]
  },
  { 
    "_id" : "67890",
    "coordinates" : [[
      [ 9.090445, 48.715736 ],
      [ 9.089583, 48.715687 ]  
    ]]
  }
]

到目前为止，我只能console.log结果，但是我需要一些有关如何将结果保存到一个变量中的建议。

这就是我得到的：

function printPolygons() {
  for (var i = 0; i < polygons.length; i++) {
    console.log('"polygon_id" : ' + JSON.stringify(polygons[i]._id, null, 4) + ",");
    console.log('"coordinates" : '+ JSON.stringify(polygons[i].geometry.coordinates, null, 4));
  };
};

输出在控制台中看起来不错，但是我需要为REST API端点提供它。 有人知道怎么做吗？ 谢谢！

Answer 1

您可以这样做

const polygons = [
  {
    "_id" : "12345",
    "geometry" : {
       "coordinates" : [[
           [9.123553, 48.71568],
           [ 9.119548, 48.71526 ]
       ]]
    }
  },
  {
    "_id" : "67890",
    "geometry" : {
       "coordinates" : [[
           [ 9.090445, 48.715736 ],
           [ 9.089583, 48.715687 ]
       ]]
    }
  }
];

const result = polygons.map(({ _id, geometry }) => {
    return {
      _id,
      coordinates: geometry.coordinates
    };
});

console.log(result);

Answer 2

var polygons = [{
        "_id": "12345",
        "geometry": {
            "coordinates": [
                [
                    [9.123553, 48.71568],
                    [9.119548, 48.71526]
                ]
            ]
        }
    },
    {
        "_id": "67890",
        "geometry": {
            "coordinates": [
                [
                    [9.090445, 48.715736],
                    [9.089583, 48.715687]
                ]
            ]
        }
    }
]

polygons = polygons.map(({
    _id,
    geometry
}) => ({
    _id,
    coordinates: geometry
}));

console.log(polygons);