HackerRank - Diagonal Difference.js

//https://www.hackerrank.com/challenges/diagonal-difference/problem?isFullScreen=true

function diagonalDifference(arr) {
    let sum1 = 0, sum2 = 0
    for(let i = 0; i < arr.length; i++ ){
        sum1 += arr[i][i]
        let j = arr.length - 1 - i 
        sum2 += arr[i][j]
        //console.log(arr[i][j])
    }
    
    return Math.abs(sum1 - sum2)
    
}