Question

我有一个地点列表：

[
 {
    "id": 1,
    "name": "Location 1",
    "city": {
        "id": 7,
        "name": "Phoenix",
    }
 },
 {
    "id": 2,
    "name": "Location 2",
    "city": {
        "id": 7,
        "name": "Phoenix",
    }
 },
 {
    "id": 3,
    "name": "Location 3",
    "city": {
        "id": 11,
        "name": "Los Angeles",
    }
 }
]

除此之外，我想创建一系列城市，每个城市都有来自该城市的位置。

示例结果：

[
  {
        "id": 7,
        "name": "Phoenix",
        "locations": [
               // location objects from Phoenix (Location 1 and Location 2)
            {
                "id": 1,
                "name": "Location 1",
                "city": {
                  "id": 7,
                  "name": "Phoenix",
                 }
             },
             {
                 "id": 2,
                 "name": "Location 2",
                 "city": {
                    "id": 7,
                    "name": "Phoenix",
                  }
              }
        ]
  },
  {
        "id": 11,
        "name": "Los Angeles",
        "locations": [
               // location objects from Los Angeles (Location 3)
            {
                 "id": 3,
                 "name": "Location 3",
                 "city": {
                    "id": 11,
                    "name": "Los Angeles",
                 }
             }
        ]
   }
]

我尝试使用.map()和.filter()来获取城市的唯一值数组。它并没有为整个city（return item.city）返回唯一且不同的值，所以我只使用了name属性（return item.city.name），因为我没有＆＃39真的关心城市身份。我得到了一系列独特的城市名称：

var cities = data.map(function (item) {
    return item.city.name;
}).filter(function (value, index, self) {
    return self.indexOf(value) === index;
});

现在我不得不构建一个将位置列为每个城市的属性的数组。提前谢谢你......

Answer 1

我首先创建一个对象，其中的键设置为城市的id。然后，如果您需要数组中的这些对象，您只需通过键调用map。例如，创建一个键入ID的对象：

＆＃13;

var arr = [{"id": 1,"name": "Location 1","city": {"id": 7,"name": "Phoenix",}},{"id": 2,"name": "Location 2","city": {"id": 7,"name": "Phoenix",}},{"id": 3,"name": "Location 3","city": {"id": 11,"name": "Los Angeles",}}]

var obj = arr.reduce((a, c) => {
    if (a[c.city.id]) a[c.city.id].push(c)
    else  a[c.city.id] = [c]
    return a
}, {})

console.log(obj)

＆＃13;

现在你有一个干净的对象，如果你想要一个数组，只需在键上添加一个地图：

＆＃13;

var arr = [{"id": 1,"name": "Location 1","city": {"id": 7,"name": "Phoenix",}},{"id": 2,"name": "Location 2","city": {"id": 7,"name": "Phoenix",}},{"id": 3,"name": "Location 3","city": {"id": 11,"name": "Los Angeles",}}]

var obj = arr.reduce((a, c) => {
    if (a[c.city.id]) a[c.city.id].locations.push(c)
    else  a[c.city.id] = {name: c.city.name, locations:[c]}
    return a
}, {})

var arr_version = Object.keys(obj).map(k => Object.assign({id: k}, obj[k]))

console.log(arr_version)

＆＃13;

如何在Javascript中重新组合对象？

1 个答案: