How to collect elements from an array?

Question

Example:

array1 = [1,2,3,4,5], array2 = [6,7,8,9,10] and the results creates a new array with the result [7,9,11,13,15]

arrayy = () => {

  var arr1 = [1, 2, 3, 4, 5];
  var arr2 = [6, 7, 8, 9, 10];
  var test = " "
  for (var i = 0; i < arr1.length; i++) {
    test += (arr1[i] + arr2[i]);

  }
  console.log(test);
}

@briosheje I see it was deleted by Tarchy and and not community - or perhaps I do not see the votes — mplungjan, Aug 20 '19 at 11:51
Please visit [help], take [tour] to see what and [asl]. Do some research, search for related topics on SO; if you get stuck, post a [mcve] of your attempt, noting input and expected output. — mplungjan, Aug 20 '19 at 11:54
@mplungjan yep, just wanted to make sure that the repost chain would end there, though :P — briosheje, Aug 20 '19 at 11:54

score 3 · Accepted Answer · answered Aug 20 '19 at 11:33

You need to use array and push the value into it, instead of appending it to string

const arrayy = () => {

  var arr1 = [1, 2, 3, 4, 5];
  var arr2 = [6, 7, 8, 9, 10];
  var test = []                            //  <-- initialize as array
  for (var i = 0; i < arr1.length; i++) {
    test.push(arr1[i] + arr2[i]);          // <-- push values to array 
  }
  console.log(test);
}

arrayy()

Nick Parsons · Answer 2 · 2019-08-20T11:41:24.280

1

Your test variable should be an array which you .push() your results to. Instead, you could .map() one array's elements to the addition of the others array's element of the same index like so:

const add_arrays = (arr1, arr2) => 
  arr1.map((n, i) => n+arr2[i]);

const array1 = [1,2,3,4,5];
const array2 = [6,7,8,9,10];

console.log(add_arrays(array1, array2)); // [7, 9, 11, 13, 15]

edited Aug 20 '19 at 11:41

answered Aug 20 '19 at 11:34

Nick Parsons

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score 1 · Answer 3 · answered Aug 20 '19 at 11:36

Assuming both arrays will always have the same length, we can do it using Array.prototype.reduce:

const array1 = [1,2,3,4,5];
const array2 = [6,7,8,9,10];

const res = array1.reduce((acc, ele, idx) => {
  return acc.concat(ele + +array2[idx]);
}, []);

console.log(res);

How to collect elements from an array?

3 Answers3