Getting Sum for all first items in each array, all second items in each array etc. ES6

Asked Jun 28 '17 at 15:41

Active Jun 28 '17 at 19:51

Viewed 638 times

I am trying to add together an undetermined amount of arrays, but only add or reduce them item by item.

I cannot figure out how to make this work in ES6 javascript.

const arrayList = [
  [1, 2, 3],
  [1, 2, 3],
  [2, 2, 2]
];

const totalRow = arrayList.map((array) => {
  const total = [];
  array.map((number, i) => {
    total[i] = (total[i] == undefined ? 0 : total[i]) + number;
  });
  return total;
});


//Output is just 3 more arrays with no change, as it seems 
//the total variable resets to an empty array with each iteration.

//what i want is this output:
[4, 6, 8]

What am I doing wrong? I tried reduce method as well but came up empty

edited Jun 28 '17 at 19:51

Praveen Kumar Purushothaman

164,888
24
203
252

asked Jun 28 '17 at 15:41

leemac33

3

Use `Array.reduce`. – lumio Jun 28 '17 at 15:44
The dupe has my answer using `Array.reduce()`, which is perfect for this use-case. `Array.map` is not a right option in this case. – Praveen Kumar Purushothaman Jun 28 '17 at 15:45
@PraveenKumar, the other dupe target matches better ... – Nina Scholz Jun 28 '17 at 15:50
@NinaScholz Lemme know the link or edit the links and add it yourself... `:)` Oh wow. You did it already. – Praveen Kumar Purushothaman Jun 28 '17 at 15:54
const totalRow = arrayList.map((array) => { return Array.isArray(array) ? array.reduce((a, b) => a+b) : array; }); – Sebastián Espinosa Jun 28 '17 at 15:54
also if you only have arrays inside the array just do the array.reduce without the ternary – Sebastián Espinosa Jun 28 '17 at 15:55
1

thank you @praveenKumar that is perfect – leemac33 Jun 28 '17 at 16:13
@leemac33 You are welcome mate! `:D` – Praveen Kumar Purushothaman Jun 28 '17 at 19:51

Getting Sum for all first items in each array, all second items in each array etc. ES6

0 Answers0