Sometimes, we want to sum elements at the same index in array of arrays into a single array with JavaScript.

In this article, we’ll look at how to sum elements at the same index in array of arrays into a single array with JavaScript.

How to sum elements at the same index in array of arrays into a single array with JavaScript?

To sum elements at the same index in array of arrays into a single array with JavaScript, we can use some array methods.

For instance, we write:

const arr = [
  [0, 1, 3],
  [2, 4, 6],
  [5, 5, 7],
  [10, 0, 3]
]
const [first] = arr
const sums = first.map((_, i) => {
  return arr.map(a => a[i]).reduce((a, b) => a + b, 0)
})
console.log(sums)

We get the first nested array from arr with destructuring and assign it to first.

Next, we call first.map with a callback that returns the items of each entry with the given index of each nested array.

Then we call reduce with a callback to sum all the entries together.

Therefore, sums is [17, 10, 19].

Conclusion

To sum elements at the same index in array of arrays into a single array with JavaScript, we can use some array methods.