Question

请考虑以下对象：

    {
    "_items": [
        {
            "_id": "player_1",
            "score": {
                "a": -4.74,
                "b": 0.71,
                "c": -4.04,
                "d": 3.37,
                "e": 0.22,
                "f": 1.09,
                "g": -2.17              
            }
        }
    ]
}

我想Map and Reduce并生成一个只包含得分对象的新对象：

{
    "a": -4.74,
    "b": 0.71,
    "c": -4.04,
    "d": 3.37,
    "e": 0.22,
    "f": 1.09,
    "g": -2.17
}

我认为这样的事情可能会朝着正确的方向发展，但似乎并没有达到我的期望：

this.service.getscore()
  .map(res => res.json())
  .map(v => v._items[0].score)
  .subscribe(data => { this.sc = data });

console.log(this.sc);会给我与第一个json相同的结果。

虽然我认识到在服务器端执行此操作可能更好更容易，但在我的情况下这是不可能的。我想知道我在尝试做什么可以在客户端用JavaScript完成。有什么建议？

Answer 1

越简单越好？：

    var json = [{
        "_items": [
            {
                "_id": "player_1",
                "score": {
                    "a": -4.74,
                    "b": 0.71,
                    "c": -4.04,
                    "d": 3.37,
                    "e": 0.22,
                    "f": 1.09,
                    "g": -2.17
                }
            }
        ]
    }, {
        "_items": [
            {
                "_id": "player_2",
                "score": {
                    "a": -4.74,
                    "b": 0.71,
                    "c": -4.04,
                    "d": 3.37,
                    "e": 0.22,
                    "f": 1.09,
                    "g": -2.17
                }
            }
        ]
    }];
var scores = [];
for (var i = 0, var j = json.length; i <= j; i++) {
    scores.push(json[i]._items[0].score);
}

Answer 2

您可以尝试下面的代码：

var item = {
  "_items": [{
      "_id": "player_1",
      "score": {
        "a": -4.74,
        "b": 0.71,
        "c": -4.04,
        "d": 3.37,
        "e": 0.22,
        "f": 1.09,
        "g": -2.17
      }
    },
    {
      "_id": "player_2",
      "score": {
        "a": -4.74,
        "b": 0.71,
        "c": -4.04,
        "d": 3.37,
        "e": 0.22,
        "f": 1.09,
        "g": -2.17
      }
    }
  ]
};
let arrayScores = item._items.map(el => el.score);
console.log(arrayScores);

有arrayScores值：

[{
  a: -4.74,
  b: 0.71,
  c: -4.04,
  d: 3.37,
  e: 0.22,
  f: 1.09,
  g: -2.17
}, {
  a: -4.74,
  b: 0.71,
  c: -4.04,
  d: 3.37,
  e: 0.22,
  f: 1.09,
  g: -2.17
}]

有意义吗？

Answer 3

正如Maria Ines Parnisari所提到的，您可以通过插入您收到的JSON来精确提取所需的数据。因此，我们只提取score的内容并将其分配给对象：

<强>服务

getscore() {
  return this.http.get('src/data.json')
    .map(res => res.json()._items[0].score) // let's get the content of 'score'
}

组件：

ngOnInit() {
  this.service.getscore()
    .subscribe(data => {
      this.sc = data;
    })
}

DEMO

Answer 4

Working demo

＆＃13;

this.sc = {
    "_items": [
        {
            "_id": "player_1",
            "score": {
                "a": -4.74,
                "b": 0.71,
                "c": -4.04,
                "d": 3.37,
                "e": 0.22,
                "f": 1.09,
                "g": -2.17              
            }
        }
    ]
};

console.log(this.sc._items[0].score);

＆＃13;

使用JavaScript映射和减少JSON对象

4 个答案: