CODEWITHSUNDEEP
javascriptarraysobject
Kanwar Rupyal
Kanwar Rupyal

Reputation: 3

Map one array elements to the elements of other nested array in js

I have two arrays like this

const arr1 = ["name", "age", "spouseName", "kids"];
const arr2 = [["John", "Jack"], [31, 44], ["Jill", "Emily"], [3, 2]];

I need to map the elements of arr1 to each nested element at the same index of arr2 so that I get result in an array with two objects like this

result = [ { "name" : "John", "age" : 31, "spouseName": "Jill", "kids" : 3 }, 
{ "name" : "Jack", "age" : 44, "spouseName": "Emily", "kids" : 2 }]

I have tried using nested forEach to loop over each of element in arr2 but it only spits out the items in index 1 and not at index 0 as it get overwritten in the loop

arr2.forEach((element, index) => {
  element.forEach((el) => {
    result[arr1[index]] = el
    })
});

I know I am missing something but can't figure out

Upvotes: 0

Views: 55

Answers (2)

Pete
Pete

Reputation: 58462

You can loop through the names in array 2 and assuming the following arrays have the correct number of elements in you can use the index of that name to get the corresponding items from the other arrays:

const arr1 = [];
const arr2 = [["John", "Jack"], [31, 44], ["Jill", "Emily"], [3, 2]];

arr2[0].forEach((item, index) => {
  arr1.push({
    "name": item, 
    "age": arr2[1][index],
    "spouseName": arr2[2][index], 
    "kids": arr2[3][index],
  });
})

console.log(arr1);

If you need to use arr1 as your property names and you don't know the number of items in arr1, I would do it like this:

const arr1 = ["name", "age", "spouseName", "kids"];
const arr2 = [
  ["John", "Jack", "1", "2", "3"],
  [31, 44, 22, 41, 42],
  ["Jill", "Emily", "1", "2", "3"],
  [3, 2, 1, 5, 2]
];

const result = arr2[0].map((name, index) => {
  let returnValue = {};
  returnValue[arr1[0]] = name;

  for (let i = 1; i < arr1.length; i++) {
    returnValue[arr1[i]] = arr2[i][index];
  }

  return returnValue;
});

console.log(result)

It is a slightly more efficient way than using reduce in your map loop: https://jsbench.me/zpl6lvmb6r/1

Upvotes: 0

wardialer
wardialer

Reputation: 492

You can loop through the arrays as follows:

const arr1 = ["name", "age", "spouseName", "kids"];
const arr2 = [["John", "Jack"], [31, 44], ["Jill", "Emily"], [3, 2]];

result = arr2[0].map((_, i) => arr1.reduce((acc, k, j) => {
    acc[k] = arr2[j][i];
    return acc;
  }, {}));

console.log(result);

Upvotes: 1

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