Transform an array of string values that occur multiple times into an array of objects organized by their index

Question

Transform an array of string values that occur multiple times into an array of objects organized by their index

Assuming I have a list structured as follows:

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

and my goal is to transform it into a list of JSON objects like this:

[
    {
        "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"
    },
    ...
]

What is the most efficient method to accomplish this task using JavaScript?

javascript arrays json javascript-objects

Answer 1

Answer №1

If I were to implement this, I would opt for a straightforward while loop approach with an initial assertion:

console.assert(data.length % 4 === 0); // This line ensures the data array is divisible by 4
const result = [];
let i = 0;
while (i < data.length) {
    result.push({
        id: data[i++],
        date: data[i++],
        name: data[i++],
        value: data[i++]
    });
}

Here's a practical demonstration:

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

If I were to implement this, I would opt for a straightforward while loop approach with an initial assertion:

console.assert(data.length % 4 === 0); // This line ensures the data array is divisible by 4
const result = [];
let i = 0;
while (i < data.length) {
    result.push({
        id: data[i++],
        date: data[i++],
        name: data[i++],
        value: data[i++]
    });
}

Here's a practical demonstration:

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 3

Answer №2

This particular method appears to offer the most efficiency as the loop only runs a quarter of the total length. If you have any alternative suggestions, please don't hesitate to share.

const data = [
    "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 resultArray = [];
for (let i=0; i < data.length; i += 4) {
  const object = {};
  object.id = data[i];
  object.date = data[i + 1] ? data[i + 1] : 'NA'; // This will verify if the index is present or not.
  object.name = data[i + 2] ? data[i + 2] : 'NA';
  object.amount =data[i + 3] ? data[i + 3] : 'NA';
  
  resultArray.push(object);
}

console.log('resultArray = ', resultArray);

Answer 4

This particular method appears to offer the most efficiency as the loop only runs a quarter of the total length. If you have any alternative suggestions, please don't hesitate to share.

const data = [
    "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 resultArray = [];
for (let i=0; i < data.length; i += 4) {
  const object = {};
  object.id = data[i];
  object.date = data[i + 1] ? data[i + 1] : 'NA'; // This will verify if the index is present or not.
  object.name = data[i + 2] ? data[i + 2] : 'NA';
  object.amount =data[i + 3] ? data[i + 3] : 'NA';
  
  resultArray.push(object);
}

console.log('resultArray = ', resultArray);

Answer 5

Answer №3

If you want to achieve this without using any loops, one way is to utilize the Array.reduce() method. With this approach, you can populate your output array by adding a new item every 4 iterations of your input data:

const data = [
    "id1", "01-01-2020", "name1", "$ 10.00",
    "id2", "02-01-2020", "name2", "$ 15.00",
    "id3", "03-01-2020", "name3", "$ 20.00",
];

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 6

If you want to achieve this without using any loops, one way is to utilize the Array.reduce() method. With this approach, you can populate your output array by adding a new item every 4 iterations of your input data:

const data = [
    "id1", "01-01-2020", "name1", "$ 10.00",
    "id2", "02-01-2020", "name2", "$ 15.00",
    "id3", "03-01-2020", "name3", "$ 20.00",
];

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 7

Answer №4

To break down the array into smaller subarrays and then convert those subarrays into objects:

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 8

To break down the array into smaller subarrays and then convert those subarrays into objects:

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 9

Answer №5

You have the option to destructure sections of an array and create a new object for appending.

const generateObject = ([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(generateObject(data.slice(i, i += 4)));
}

console.log(result);

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

Answer 10

You have the option to destructure sections of an array and create a new object for appending.

const generateObject = ([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(generateObject(data.slice(i, i += 4)));
}

console.log(result);

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

Answer 11

Answer №6

Utilize the Array.from method to accomplish a task without hardcoding keys in a loop. This approach is suitable for processing any number of predetermined keys as long as the input array data is valid.

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((result, key, j) => ({ ...result, [key]: array[i * keys.length + j] }), {})
);

console.log(output)

Answer 12

Utilize the Array.from method to accomplish a task without hardcoding keys in a loop. This approach is suitable for processing any number of predetermined keys as long as the input array data is valid.

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((result, key, j) => ({ ...result, [key]: array[i * keys.length + j] }), {})
);

console.log(output)

Transform an array of string values that occur multiple times into an array of objects organized by their index

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

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