Given a square matrix, calculate the absolute difference between the sums of its diagonals.

For example, the square matrix is shown below:

`1 2 3`

4 5 6

9 8 9

The left-to-right diagonal = 1+5+9=15 . The right to left diagonal = 3+5+9=17. Their absolute difference is |15–17|=2.

function diagonalDifference(arr) {

let idx = arr.length - 1

let rightTotal = 0

let leftTotal = 0 for (let i = 0; i < arr.length; i++) {

rightTotal += arr[i][i]

leftTotal += arr[i][idx]

idx--

}

return Math.abs(rightTotal - leftTotal)

}