HackerRank Diagonal Difference js [SOLVED]

diagonalDiffrence.js

function diagonalDifference(arr) {
    // Write your code here
    let right=0;
    let left=0;
    let len = arr.length;
    for(var i=0;i<len;i++){
        for(var j=0;j<len;j++){
            if(i - j == 0) {
                left = left +arr[i][j];
            }
             if (i + j == len -1) {
                right = right +arr[i][j];
             } 
        }
    }
    return Math.abs(left - right);
}
var items = [
    [7, 2, 3],
    [3, 4, 7],
    [5, 6, -1]
  ];

  console.log(diagonalDifference(items));