javascript - Javascript 对象转换

Question

数据数组有 3 个对象，每个对象有 3 个键，即 key、c​​ity 和 fair。现在我想以这样一种方式进行析构，即城市和公平被隔离在单独的 JS 对象中（如下所示）

我怎样才能进行这样的转换？

输入

const data = [
  {
    "key": 1,
    "city": "Delhi",
    "fair": 4500
  },
  {
    "key": 2,
    "city": "Ahmedabad",
    "fair": 2500
  },
  {
    "key": 3,
    "city": "Mumbai",
    "fair": 5000
  }
];

预期产出

const city = [
  {
    "key": 1,
    "value": "Delhi"
  },
  {
    "key": 1,
    "value": "Ahmedabad"
  },
  {
    "key": 1,
    "value": "Mumbai"
  }
];

const fair = [
  {
    "key": 1,
    "value": 4500
  },
  {
    "key": 1,
    "value": 2500
  },
  {
    "key": 1,
    "value": 5000
  }
];

标签： javascriptarraysjsonobject

Answer 1

您可以使用Array#reduce()调用将每个属性累积到一个单独的数组中。

如果您事先知道要分组的键，则可以在初始累加器中声明它们并显式调用它们。

const input = [{ "key": 1, "city": "Delhi", "fair": 4500 }, { "key": 2, "city": "Ahmedabad", "fair": 2500 }, { "key": 3, "city": "Mumbai", "fair": 5000 }];

const { city, fair } = input.reduce((acc, { key, city, fair }) => {
  acc.city.push({ key, value: city });
  acc.fair.push({ key, value: fair });

  return acc;
}, { city: [], fair: [] });

console.log(city);
console.log(fair);

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但是如果你有大量的属性，你可能需要一个更动态的选项，在这里分离key和迭代Object.entries()任何剩余的属性，并在累加器中按键对它们进行分组。

const input = [{ "key": 1, "city": "Delhi", "fair": 4500 }, { "key": 2, "city": "Ahmedabad", "fair": 2500 }, { "key": 3, "city": "Mumbai", "fair": 5000 }];

const { city, fair } = input.reduce((acc, { key, ...data }) => {
  Object.entries(data).forEach(([prop, value]) => {
    (acc[prop] ??= []).push({ key, value });
  });
  return acc;
}, {});

console.log(city);
console.log(fair);

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