Question

我需要建立一张地图＆＃34; A＆＃34;来自现有的对象数组。但是，映射A上的键值对来自现有对象键的值＆＃34; id＆＃34;和＆＃34; cap＆＃34;。

是否可以读取2个键的值并存储为对象

  var items =  [{
                "id": 1,
                "name": "Primary",
                "cap": [{
                        "id": "1",
                        "name": "1s"
                    }, {
                        "id": "2",
                        "name": "T2s"
                    }]
                },{
                "id": 2,
                "name": "Secondary",
                "cap": [{
                        "id": "1",
                        "name": "1s"
                    }, {
                        "id": "2",
                        "name": "T2s"
                    }
                ]
            }]

我的地图需要像这样

          { "1" : [{
                        "id": "1",
                        "name": "1s"
                    }, {
                        "id": "2",
                        "name": "T2s"
                    }],
              "2" : [{
                        "id": "1",
                        "name": "1s"
                    }, {
                        "id": "2",
                        "name": "T2s"
                    }]
 }

Answer 1

使用Array#reduce获得如下结果：

＆＃13;

var items = [{
  "id": 1,
  "name": "Primary",
  "cap": [{
    "id": "1",
    "name": "1s"
  }, {
    "id": "2",
    "name": "T2s"
  }]
}, {
  "id": 2,
  "name": "Secondary",
  "cap": [{
    "id": "1",
    "name": "1s"
  }, {
    "id": "2",
    "name": "T2s"
  }]
}];

var ans = items.reduce(function(v, i) {
  v[i.id] = i.cap;
  return v;
}, {});

console.log(ans);

＆＃13;

Answer 2

你可以在原始数组上使用一个简单的循环，并在对象中定义一个新的key：value对。

// Create the map
var map = {}
// For every 'item' within the 'items' array
items.forEach(item => {
    // Map the item ID to the item.cap array
    map[item.id] = item.cap
}

＆＃13;

var items = [{
  "id": 1,
  "name": "Primary",
  "cap": [{
    "id": "1",
    "name": "1s"
  }, {
    "id": "2",
    "name": "T2s"
  }]
}, {
  "id": 2,
  "name": "Secondary",
  "cap": [{
    "id": "1",
    "name": "1s"
  }, {
    "id": "2",
    "name": "T2s"
  }]
}]

var map = {}
items.forEach(item => {
  map[item.id] = item.cap
})

console.log(map)

＆＃13;

Answer 3

使用ES6 Array.from()方法。

＆＃13;

 var items =  [{
                "id": 1,
                "name": "Primary",
                "cap": [{
                        "id": "1",
                        "name": "1s"
                    }, {
                        "id": "2",
                        "name": "T2s"
                    }]
                },{
                "id": 2,
                "name": "Secondary",
                "cap": [{
                        "id": "1",
                        "name": "1s"
                    }, {
                        "id": "2",
                        "name": "T2s"
                    }
                ]
            }];

var obj = {};
var res = Array.from(items, x => obj[x.id] = x.cap);

console.log(obj);

＆＃13;

使用数组javascript中的多个对象的值构建映射

3 个答案: