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I want to convert the following array:

const data = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]];

to the following object:

const data = [
  {
    a: 1,
    b: 2,
    c: 3,
    d: 4
  },
  {
    a: 5,
    b: 6,
    c: 7,
    d: 8
  },
  {
    a: 9,
    b: 10,
    c: 11,
    d: 12
  }
];

How do I do it using loop or some other way, of course?

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  • 1
    Have you tried anything yet that you're having trouble with? I'd suggest you start by looking at Array.prototype.map and Array.prototype.reduce Commented Jun 13, 2019 at 3:01

2 Answers 2

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7

This is a basic map / reduce operation where you map the outer array to a new one where each value (array) is reduced to a single object.

Given the simple nature of each value (a single array with four values), you can skip Array.prototype.reduce() for some array destructuring.

For example

const data = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]];

const newData = data.map(([ a, b, c, d ]) => ({ a, b, c, d }))

console.info(newData)

Note that this really hinges on knowing the data structure and no surprises (more or fewer elements in each array for example).

If you wanted a much more robust version, you'll want something like this

const data = [[1, 2, 3, 4], [5, 6, 7], [8, 9, 10, 11, 12]];

const newData = data.map(arr => arr.reduce((obj, val, idx) => ({
  ...obj,
  [String.fromCharCode(97 + idx)]: val
}), Object.create(null)))

console.info(newData)

The only thing to worry about here is if your arrays contain more than 26 elements. Then your object keys are going to get weird.

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1

You can use Array.prototype.map() combined with Array.prototype.reduce()

Code:

const alphabet = [...'abcdefghijklmnopqrstuvwxyz'];
const data = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]];
const reasult = data.map(arr => arr.reduce((a, c, i) => (a[alphabet[i]] = c, a), {}));

console.log(reasult);

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