diagonalDifference.js

function diagonalDifference(arr) {

let i=0; let j=0; let firstSum=0; let secondSum=0;
j=arr.length-1;

for(i=0;i<arr.length; i++){
 
  firstSum=firstSum+arr[i][i]
  secondSum = secondSum + arr[i][j-i]}

return Math.abs(firstSum-secondSum)
 
}