Question

假设我有一个这样的列表结构：

[
    "id1", "01-01-2019", "name1", "€ 5,60",
    "id2", "02-01-2019", "name2", "€ 5,70",
    "id3", "03-01-2019", "name3", "€ 5,20",
    ...
]

，我想将其转换为带有json对象的列表，如下所示：

[
    {
        "id": "id1", 
        "date": "01-01-2019", 
        "name": "name1", 
        "value": "€ 5,60"
    },
    {
        "id": "id2", 
        "date": "02-01-2019", 
        "name": "name2", 
        "value": "€ 5,70"
    },
    {
        "id": "id3", 
        "date": "03-01-2019", 
        "name": "name3", 
        "value": "€ 5,20"
    },
    ...
]

在JavaScript中最有效的方法是什么？

Answer 1

我将使用带有预先声明的简单while循环：

console.assert(data.length % 4 === 0); // Or whatever you use for assertions
const result = [];
let i = 0;
while (i < data.length) {
    result.push({
        id: data[i++],
        date: data[i++],
        name: data[i++],
        value: data[i++]
    });
}

实时示例：

const data = [
    "id1", "01-01-2019", "name1", "€ 5,60",
    "id2", "02-01-2019", "name2", "€ 5,70",
    "id3", "03-01-2019", "name3", "€ 5,20"
];

console.assert(data.length % 4 === 0);
const result = [];
let i = 0;
while (i < data.length) {
    result.push({
        id: data[i++],
        date: data[i++],
        name: data[i++],
        value: data[i++]
    });
}

console.log(result);

.as-console-wrapper {
  max-height: 100% !important;
}

Answer 2

我认为这种方法将是最有效的，因为循环运行了1/4次。如果您还有其他建议，请随时提出建议。

const array = [
    "id1", "01-01-2019", "name1", "€ 5,60",
    "id2", "02-01-2019", "name2", "€ 5,70",
    "id3", "03-01-2019", "name3", "€ 5,20",
    'id4', '03-01-2019'
];

const finalArray = [];
for (let i=0; i < array.length; i += 4) {
  const obj = {};
  obj.id = array[i];
  obj.data = array[i + 1] ? array[i + 1] : 'NA'; // This will check the index is available or not.
  obj.name = array[i + 2] ? array[i + 2] : 'NA';
  obj.value =array[i + 3] ? array[i + 3] : 'NA';
  
  finalArray.push(obj);
}

console.log('finalArray = ', finalArray);

Answer 3

您可以使用Array.reduce()进行无循环操作，方法是在输入数据上每4次迭代将一个新项推送到输出中：

const data = [
    "id1", "01-01-2019", "name1", "€ 5,60",
    "id2", "02-01-2019", "name2", "€ 5,70",
    "id3", "03-01-2019", "name3", "€ 5,20",
];

const result = data.reduce((acc, _, i, arr) => {
  if (i % 4 === 0) {
    acc.push({ id: arr[i], date: arr[i+1], name: arr[i+2], value: arr[i+3] });
  }
  return acc;
}, []);

console.log(result);

Answer 4

您可以对数组的各个部分进行分解，并构建一个用于推送的新对象。

const makeObject = ([id, date, name, value]) => ({ id, date, name, value });

var data = ["id1", "01-01-2019", "name1", "€ 5,60", "id2", "02-01-2019", "name2", "€ 5,70", "id3", "03-01-2019", "name3", "€ 5,20"],
    i = 0,
    result = [];

while (i < data.length) {
    result.push(makeObject(data.slice(i, i += 4)));
}

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 5

将数组划分为子数组，然后将这些数组映射到对象：

const arr = [
    "id1", "01-01-2019", "name1", "€ 5,60",
    "id2", "02-01-2019", "name2", "€ 5,70",
    "id3", "03-01-2019", "name3", "€ 5,20"
]

const result = chunk(arr, 4).map(item => ({ id: item[0], date: item[1], name: item[2], cost: item[3]}))

console.log(result)

function chunk(arr, size) {
	const result = []

	for (let i = 0; i < arr.length; i += size)
		result.push(arr.slice(i, i + size))

	return result
}

Answer 6

您可以使用Array.from做某事。此处，密钥未在循环中进行硬编码。只要您具有有效的输入数组数据，此方法就可以任意数量的预定义 keys。

const array = [
    "id1", "01-01-2019", "name1", "€ 5,60",
    "id2", "02-01-2019", "name2", "€ 5,70",
    "id3", "03-01-2019", "name3", "€ 5,20",
]

const keys = ["id", "date", "name", "value"],
    length =  array.length / keys.length;

const output = Array.from({ length }, (_, i) =>
    keys.reduce((r,k,j) => ({ ...r, [k]: array[i * keys.length + j] }), {})
  );
  
console.log(output)

将具有重复值的字符串数组转换为基于索引的对象数组

6 个答案: